Ataxia Evaluation¶

VERSION: 1.1 CREATED: January 30, 2026 REVISED: January 31, 2026 STATUS: Approved

DIAGNOSIS: Ataxia Evaluation

ICD-10: R27.0 (Ataxia, unspecified), G11.9 (Hereditary ataxia, unspecified), G11.1 (Early-onset cerebellar ataxia), G11.2 (Late-onset cerebellar ataxia), G11.0 (Congenital nonprogressive ataxia), G11.3 (Cerebellar ataxia with defective DNA repair), G11.4 (Hereditary spastic paraplegia), G31.89 (Other specified degenerative diseases of nervous system — cerebellar degeneration NOS), G32.81 (Cerebellar ataxia in diseases classified elsewhere), G13.1 (Other systemic atrophy primarily affecting central nervous system in neoplastic disease — paraneoplastic cerebellar degeneration)

CPT CODES: 85025 (CBC with differential), 80053 (CMP), 82947 (Blood glucose), 84443 (TSH), 82607 (Vitamin B12), 82746 (Folate), 82608 (Vitamin E level), 83735 (Magnesium), 85652 (ESR), 80320 (Blood alcohol level), 86235 (Anti-GAD65 antibodies), 86258 (Anti-gliadin antibodies (IgA and IgG)), 86364 (Tissue transglutaminase IgA), 86255 (Paraneoplastic antibody panel), 83921 (Methylmalonic acid), 83090 (Homocysteine), 84425 (Thiamine (vitamin B1) level), 82525 (24-hour urine copper), 80061 (Lipid panel), 83036 (HbA1c), 86592 (RPR/VDRL), 87389 (HIV screening), 81401 (Genetic testing — SCA panel), 81284 (Genetic testing — Friedreich ataxia (FXN gene)), 81408 (Genetic testing — ataxia-telangiectasia (ATM gene)), 81406 (Genetic testing — episodic ataxia (CACNA1A, KCNA1)), 81415 (Whole exome sequencing), 82542 (Very long chain fatty acids (VLCFA)), 82105 (Alpha-fetoprotein (AFP)), 70450 (CT head without contrast), 70553 (MRI brain with and without contrast), 74177 (CT chest/abdomen/pelvis with contrast), 78816 (PET-CT), 95907-95913 (Nerve conduction study / Electromyography (NCS/EMG)), 95816 (Electroencephalogram (EEG)), 76390 (MR spectroscopy of cerebellum), 78830 (DAT scan (DaTscan, ioflupane SPECT)), 75557 (Cardiac MRI), 93306 (Echocardiogram (TTE)), 95923 (Autonomic function testing)

SYNONYMS: Ataxia, cerebellar ataxia, sensory ataxia, gait ataxia, limb ataxia, truncal ataxia, spinocerebellar ataxia, SCA, Friedreich ataxia, Friedreich's ataxia, hereditary ataxia, acquired ataxia, paraneoplastic cerebellar degeneration, autoimmune cerebellar ataxia, gluten ataxia, alcohol cerebellar degeneration, episodic ataxia, ataxia-telangiectasia, MSA-C, multiple system atrophy cerebellar type, sporadic adult-onset ataxia, SAOA, incoordination, unsteady gait, cerebellar syndrome, imbalance

SCOPE: Evaluation and management of ataxia in adults. Covers the differential diagnosis approach to cerebellar vs. sensory ataxia, acute/subacute etiologies (stroke, toxic, infectious, paraneoplastic, autoimmune), and chronic/progressive etiologies (hereditary, degenerative, immune-mediated). Includes diagnostic workup, etiology-directed treatment, symptomatic management, and rehabilitation. Excludes isolated vertigo (see Vertigo/Dizziness Evaluation), ataxia in children, and ataxia secondary to acute intoxication without persistent deficits.

DEFINITIONS: - Cerebellar ataxia: Incoordination due to cerebellar dysfunction; characterized by dysmetria, intention tremor, dysdiadochokinesia, nystagmus, dysarthria (scanning speech), and wide-based gait - Sensory ataxia: Incoordination due to impaired proprioception (dorsal columns, peripheral nerves); characterized by Romberg sign, pseudoathetosis, loss of vibration/position sense, worsened by eye closure - Acute ataxia: Onset within hours to days (stroke, toxic, infectious) - Subacute ataxia: Onset over weeks to months (paraneoplastic, autoimmune, nutritional) - Chronic ataxia: Onset over months to years (hereditary, degenerative) - Episodic ataxia: Recurrent discrete episodes of ataxia with return to baseline (genetic channelopathies)

PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting

=============================================================== SECTION A: ACTION ITEMS ===============================================================

1. LABORATORY WORKUP¶

1A. Essential/Core Labs¶

Test	Rationale	Target Finding	ED	HOSP	OPD	ICU
CBC with differential (CPT 85025)	Infection screen (cerebellitis, abscess); anemia (B12 deficiency); malignancy (paraneoplastic)	Normal; leukocytosis suggests infection; macrocytic anemia suggests B12/folate deficiency	STAT	STAT	ROUTINE	STAT
CMP (CPT 80053)	Electrolyte derangements (hyponatremia, uremia); hepatic encephalopathy; renal dysfunction affecting drug clearance	Normal; hyponatremia <130 mEq/L can cause neurologic symptoms; elevated ammonia/LFTs suggest hepatic cause	STAT	STAT	ROUTINE	STAT
Blood glucose (CPT 82947)	Hypoglycemia can mimic acute cerebellar dysfunction; diabetes as comorbidity in neuropathic ataxia	70-180 mg/dL	STAT	STAT	ROUTINE	STAT
TSH (CPT 84443)	Hypothyroidism can cause cerebellar ataxia (rare but treatable); thyroid dysfunction in autoimmune conditions	Normal (0.4-4.0 mIU/L); hypothyroidism → thyroid replacement	-	ROUTINE	ROUTINE	-
Vitamin B12 (CPT 82607)	B12 deficiency causes subacute combined degeneration with sensory ataxia; posterior column disease	>300 pg/mL; low or borderline → methylmalonic acid and homocysteine	URGENT	URGENT	ROUTINE	URGENT
Folate (CPT 82746)	Folate deficiency can contribute to neuropathy and myelopathy causing sensory ataxia	Normal (>5.9 ng/mL); low → supplement	-	ROUTINE	ROUTINE	-
Vitamin E level (CPT 82608)	Vitamin E deficiency causes spinocerebellar syndrome mimicking Friedreich ataxia; fat malabsorption states	Normal (5.5-17 mg/L); deficiency → supplement and evaluate malabsorption	-	ROUTINE	ROUTINE	-
Magnesium (CPT 83735)	Hypomagnesemia can contribute to ataxia and tremor; often low in alcoholism	Normal (1.7-2.2 mg/dL); low → replace	STAT	STAT	ROUTINE	STAT
ESR (CPT 85652) / CRP (CPT 86140)	Inflammatory markers for autoimmune, infectious, or paraneoplastic etiologies	Normal; elevated → further autoimmune/infectious workup	URGENT	URGENT	ROUTINE	URGENT
Drug levels (phenytoin, lithium, carbamazepine) (CPT 80185/80178/80156)	Drug toxicity is common reversible cause of cerebellar ataxia; phenytoin toxicity is classic cause	Phenytoin 10-20 mcg/mL; lithium 0.6-1.2 mEq/L; carbamazepine 4-12 mcg/mL; supratherapeutic levels → dose adjust or discontinue	STAT	STAT	ROUTINE	STAT
Blood alcohol level (CPT 80320)	Acute alcohol intoxication; chronic alcoholic cerebellar degeneration	Negative or low; elevated → address intoxication	STAT	STAT	-	STAT
Urinalysis with drug screen (CPT 81003/80307)	Toxic exposures; illicit substances causing ataxia	Negative; positive → identify offending agent	STAT	STAT	-	STAT

1B. Extended Workup (Second-line)¶

Test	Rationale	Target Finding	ED	HOSP	OPD	ICU
Anti-GAD65 antibodies (CPT 86235)	Autoimmune cerebellar ataxia; stiff-person spectrum; high titers (>2000 IU/mL) associated with cerebellar ataxia	Negative; positive at high titers → autoimmune cerebellar ataxia	-	URGENT	ROUTINE	-
Anti-gliadin antibodies (IgA and IgG) (CPT 86258)	Gluten ataxia is most common autoimmune cause of sporadic ataxia; may occur without GI symptoms	Negative; positive → trial gluten-free diet; tissue transglutaminase (tTG) for celiac confirmation	-	ROUTINE	ROUTINE	-
Tissue transglutaminase IgA (CPT 86364)	Celiac disease confirmation when anti-gliadin positive; gluten ataxia	Negative; positive → confirm with duodenal biopsy; strict gluten-free diet	-	ROUTINE	ROUTINE	-
Paraneoplastic antibody panel (CPT 86255)	Paraneoplastic cerebellar degeneration (PCD); anti-Yo (ovarian, breast), anti-Hu (small cell lung), anti-Tr/DNER (Hodgkin lymphoma), anti-mGluR1, anti-CV2/CRMP5	Negative; positive → CT chest/abdomen/pelvis and PET-CT for occult malignancy	-	URGENT	ROUTINE	-
Methylmalonic acid (CPT 83921)	Confirms functional B12 deficiency when B12 borderline (200-400 pg/mL)	Normal (<0.4 mcmol/L); elevated → B12 deficiency confirmed	-	ROUTINE	ROUTINE	-
Homocysteine (CPT 83090)	Elevated in B12 and folate deficiency; vascular risk factor	Normal (<15 mcmol/L); elevated → supplement B12/folate	-	ROUTINE	ROUTINE	-
ANA (CPT 86235)	Systemic autoimmune conditions causing CNS involvement (SLE cerebritis, Sjogren syndrome)	Negative; positive → further autoimmune workup (dsDNA, SSA/SSB, complement)	-	ROUTINE	ROUTINE	-
Copper and ceruloplasmin (CPT 82390/82390)	Wilson disease (onset typically <50 years); copper deficiency from zinc excess or malabsorption can cause ataxia	Ceruloplasmin >20 mg/dL; low ceruloplasmin + low serum copper → Wilson disease; low copper → copper deficiency myelopathy	-	ROUTINE	ROUTINE	-
Thiamine (vitamin B1) level (CPT 84425)	Wernicke encephalopathy (ataxia, ophthalmoplegia, confusion); alcoholism, malnutrition	Normal (70-180 nmol/L); low → IV thiamine replacement urgently	STAT	STAT	ROUTINE	STAT
24-hour urine copper (CPT 82525)	Wilson disease confirmation; elevated urinary copper excretion	<40 mcg/24h normal; >100 mcg/24h suggestive of Wilson disease	-	ROUTINE	ROUTINE	-
Lipid panel (CPT 80061)	Vascular risk factors if stroke-related cerebellar infarction	LDL <70 (high risk); assess global vascular risk	-	ROUTINE	ROUTINE	-
HbA1c (CPT 83036)	Diabetic neuropathy contributing to sensory ataxia; vascular risk	<7.0%; elevated → diabetes management	-	ROUTINE	ROUTINE	-
RPR/VDRL (CPT 86592)	Neurosyphilis (tabes dorsalis causing sensory ataxia); rare but treatable	Negative; positive → FTA-ABS confirmation and CSF analysis	-	ROUTINE	ROUTINE	-
HIV screening (CPT 87389)	HIV-associated cerebellar degeneration; opportunistic infections (PML, toxoplasmosis); medication-related	Negative; positive → CD4 count, viral load, CNS evaluation	-	ROUTINE	ROUTINE	-

1C. Rare/Specialized (Refractory or Atypical)¶

Test	Rationale	Target Finding	ED	HOSP	OPD	ICU
Genetic testing — SCA panel (CPT 81401)	Spinocerebellar ataxia types 1, 2, 3, 6, 7, 8, 10, 12, 17; repeat expansion testing; family history of progressive ataxia	Negative; positive → specific SCA subtype identified; genetic counseling	-	-	EXT	-
Genetic testing — Friedreich ataxia (FXN gene) (CPT 81284)	Friedreich ataxia (GAA repeat expansion); onset typically <25 years; cardiomyopathy, scoliosis, diabetes	Negative; positive (>66 GAA repeats on both alleles) → cardiologic evaluation, diabetes screening	-	-	EXT	-
Genetic testing — ataxia-telangiectasia (ATM gene) (CPT 81408)	Ataxia-telangiectasia; childhood onset but mild forms present in adults; telangiectasias, immunodeficiency, cancer predisposition	Negative; positive → cancer surveillance, immunology referral	-	-	EXT	-
Genetic testing — episodic ataxia (CACNA1A, KCNA1) (CPT 81406)	Episodic ataxia type 1 (KCNA1) and type 2 (CACNA1A); recurrent episodes; EA2 responsive to acetazolamide	Negative; positive → targeted therapy (acetazolamide for EA2)	-	-	EXT	-
Whole exome sequencing (CPT 81415)	Undiagnosed hereditary ataxia after targeted panels negative; novel or rare genetic causes	Variant of uncertain significance or pathogenic variant identified; many ataxias have no known genetic cause	-	-	EXT	-
Anti-mGluR1 antibodies	Autoimmune cerebellar ataxia; Hodgkin lymphoma association	Negative; positive → malignancy search and immunotherapy	-	-	EXT	-
Anti-DPPX antibodies	Autoimmune encephalitis with ataxia, hyperexcitability, diarrhea	Negative; positive → immunotherapy	-	-	EXT	-
Anti-CASPR2 antibodies (CPT 86255)	Autoimmune cerebellar ataxia; neuromyotonia; Morvan syndrome	Negative; positive → immunotherapy, thymoma search	-	-	EXT	-
Very long chain fatty acids (VLCFA) (CPT 82542)	Adrenomyeloneuropathy (X-linked); peroxisomal disorders causing ataxia and myelopathy	Normal; elevated → adrenoleukodystrophy/adrenomyeloneuropathy	-	-	EXT	-
Alpha-fetoprotein (AFP) (CPT 82105)	Elevated in ataxia-telangiectasia; screening marker	Normal; elevated → ataxia-telangiectasia evaluation	-	-	EXT	-
CoQ10 level (CPT 82542)	Coenzyme Q10 deficiency causes treatable cerebellar ataxia	Normal; low → CoQ10 supplementation (responds well)	-	-	EXT	-
Phytanic acid (CPT 82542)	Refsum disease (phytanic acid oxidase deficiency); ataxia, retinitis pigmentosa, neuropathy	Normal; elevated → dietary modification (phytanic acid restriction)	-	-	EXT	-

2. DIAGNOSTIC IMAGING & STUDIES¶

2A. Essential/First-line¶

Study	Timing	Target Finding	Contraindications	ED	HOSP	OPD	ICU
CT head without contrast (CPT 70450)	STAT in acute ataxia for hemorrhage or mass effect; does NOT adequately visualize posterior fossa	Cerebellar hemorrhage; posterior fossa mass; hydrocephalus; large cerebellar infarction with edema; NEGATIVE CT does NOT exclude posterior fossa stroke	None for non-contrast	STAT	STAT	-	STAT
MRI brain with and without contrast (CPT 70553)	Gold standard for cerebellar evaluation; assess atrophy pattern, lesions, enhancement; DWI for acute stroke	Cerebellar atrophy (global vs. vermian vs. hemispheric); acute infarction on DWI; demyelinating lesions (MS); tumor; abscess; enhancement (inflammation, tumor)	MRI-incompatible implants; severe claustrophobia; GFR <30 for gadolinium	URGENT	URGENT	ROUTINE	URGENT
MRA head and neck (CPT 70544/70547) or CTA head and neck (CPT 70496/70498)	If vascular etiology suspected (vertebrobasilar stroke, dissection)	Vertebral artery dissection or stenosis; basilar artery stenosis or occlusion; posterior circulation aneurysm	MRA: MRI-incompatible implants, severe claustrophobia, GFR <30 for gadolinium; CTA: contrast allergy, renal impairment	URGENT	URGENT	ROUTINE	URGENT

2B. Extended¶

Study	Timing	Target Finding	Contraindications	ED	HOSP	OPD	ICU
MRI cervical and thoracic spine (CPT 72141/72146)	If sensory ataxia suspected; dorsal column disease; myelopathy; B12 deficiency; copper deficiency	Dorsal column hyperintensity (subacute combined degeneration); compressive myelopathy; demyelinating lesions; syrinx	MRI-incompatible implants	-	URGENT	ROUTINE	-
CT chest/abdomen/pelvis with contrast (CPT 74177)	Paraneoplastic cerebellar degeneration — malignancy search when paraneoplastic antibodies positive	Occult malignancy (lung, ovarian, breast, lymphoma); thymoma	Contrast allergy; renal impairment	-	URGENT	ROUTINE	-
PET-CT (CPT 78816)	Occult malignancy search when paraneoplastic antibodies positive and CT negative	Hypermetabolic lesion suggesting occult neoplasm; small cell lung cancer, ovarian cancer, Hodgkin lymphoma	Pregnancy; significant hyperglycemia	-	URGENT	ROUTINE	-
Nerve conduction study / Electromyography (NCS/EMG) (CPT 95907-95913)	Sensory ataxia evaluation; peripheral neuropathy; Friedreich ataxia (sensory neuropathy); CIDP; paraneoplastic neuropathy	Sensory neuropathy (reduced SNAP amplitudes); sensory neuronopathy (non-length-dependent); demyelinating neuropathy (CIDP)	Anticoagulation (relative for EMG)	-	ROUTINE	ROUTINE	-
Electroencephalogram (EEG) (CPT 95816)	If seizures suspected; progressive myoclonus ataxia syndromes; prion disease (periodic sharp waves)	Normal background; epileptiform discharges; periodic sharp wave complexes (CJD); myoclonic correlates	None	-	ROUTINE	ROUTINE	-

2C. Rare/Specialized¶

Study	Timing	Target Finding	Contraindications	ED	HOSP	OPD	ICU
MR spectroscopy of cerebellum (CPT 76390)	Evaluate cerebellar metabolites in neurodegenerative ataxia; NAA reduction in neuronal loss	Reduced NAA/Cr ratio (neuronal loss); elevated choline (inflammation or tumor); lactate peak (mitochondrial disease)	MRI-incompatible implants; severe claustrophobia; GFR <30 for gadolinium	-	-	EXT	-
DAT scan (DaTscan, ioflupane SPECT) (CPT 78830)	Differentiate MSA-C from cerebellar ataxia without parkinsonism; presynaptic dopaminergic deficit	Normal uptake (pure cerebellar) vs. reduced uptake (MSA-C, Parkinson-plus)	None significant	-	-	EXT	-
Cardiac MRI (CPT 75557)	Friedreich ataxia — hypertrophic cardiomyopathy screening; cardiac iron deposition	Normal; hypertrophic cardiomyopathy; myocardial fibrosis	MRI-incompatible implants; claustrophobia	-	-	EXT	-
Echocardiogram (TTE) (CPT 93306)	Friedreich ataxia — cardiomyopathy screening; MSA — autonomic cardiac involvement	Normal; hypertrophic or dilated cardiomyopathy (Friedreich); LV dysfunction	None	-	ROUTINE	ROUTINE	-
Autonomic function testing (CPT 95923)	MSA-C evaluation; autonomic failure (orthostatic hypotension, urinary dysfunction, anhidrosis)	Normal; abnormal (cardiovagal, adrenergic, or sudomotor dysfunction) → supports MSA-C diagnosis	None significant	-	-	EXT	-

LUMBAR PUNCTURE¶

Indication: Subacute ataxia with suspected infectious, inflammatory, autoimmune, or neoplastic etiology; acute ataxia if meningoencephalitis suspected Timing: URGENT if acute/subacute presentation; ROUTINE for chronic ataxia evaluation Volume Required: 10-15 mL standard diagnostic

Study	Rationale	Target Finding	ED	HOSP	OPD	ICU
Opening pressure	Elevated ICP (mass lesion, hydrocephalus, meningitis)	10-20 cm H2O; elevated → obtain imaging before LP; initiate ICP management	URGENT	URGENT	ROUTINE	-
Cell count (tubes 1 and 4)	Infection, inflammation, malignancy	WBC <5, RBC 0; pleocytosis → infection or inflammation; lymphocytic → viral, autoimmune, or paraneoplastic	URGENT	URGENT	ROUTINE	-
Protein	Infection, inflammation, Guillain-Barre variants	15-45 mg/dL; elevated → infection, inflammation, malignancy; markedly elevated → GBS variant (Miller Fisher)	URGENT	URGENT	ROUTINE	-
Glucose with serum glucose	Infection (bacterial, TB, fungal)	CSF/serum ratio >0.6; low ratio → bacterial, TB, fungal, or carcinomatous meningitis	URGENT	URGENT	ROUTINE	-
Gram stain and culture	Bacterial meningitis; brain abscess rupture	No organisms; positive → targeted antibiotics	URGENT	URGENT	-	-
Oligoclonal bands and IgG index	Multiple sclerosis; other inflammatory CNS disease	Absent; present → MS or other inflammatory condition	-	ROUTINE	ROUTINE	-
Cytology	Leptomeningeal carcinomatosis; CNS lymphoma	Negative; positive → oncology referral	-	ROUTINE	ROUTINE	-
Anti-GAD65 in CSF	Intrathecal anti-GAD production in autoimmune cerebellar ataxia	Negative; positive (especially with high index vs. serum) → autoimmune cerebellar ataxia	-	ROUTINE	ROUTINE	-
Paraneoplastic antibodies in CSF	More sensitive than serum for some paraneoplastic antibodies	Negative; positive → malignancy search	-	ROUTINE	ROUTINE	-
14-3-3 protein and RT-QuIC	Prion disease (Creutzfeldt-Jakob disease) if rapidly progressive ataxia with cognitive decline	Negative; positive → CJD highly likely	-	ROUTINE	EXT	-

Special Handling: CSF for cytology must be processed within 1 hour; paraneoplastic and autoimmune panels require specific handling per reference laboratory Contraindications: Posterior fossa mass with risk of herniation; severe coagulopathy (INR >1.5, platelets <50,000); skin infection at puncture site

3. TREATMENT¶

3A. Acute/Emergent Treatment¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Thiamine (vitamin B1)	IV	Wernicke encephalopathy (ataxia + ophthalmoplegia + confusion); empiric in alcoholism or malnutrition with acute ataxia	500 mg :: IV :: TID x 3 days :: 500 mg IV TID for 3 days, then 250 mg IV daily for 5 days; give BEFORE glucose; infuse over 30 min	Rare anaphylaxis (IV formulation)	Allergic reaction during infusion; clinical improvement (ophthalmoplegia resolves first, then confusion, then ataxia)	STAT	STAT	-	STAT
IV alteplase (tPA)	IV	Acute posterior circulation ischemic stroke causing cerebellar infarction within treatment window	0.9 mg/kg :: IV :: once (max 90 mg) :: 0.9 mg/kg IV (max 90 mg); 10% bolus over 1 min, remainder over 60 min; within 4.5 hours of symptom onset	Active hemorrhage; recent surgery; INR >1.7; platelets <100,000; BP >185/110; see full stroke exclusion criteria	BP q15min x 2h, then q30min x 6h, then q1h x 16h; neuro checks q15min during infusion; NIHSS; signs of hemorrhage	STAT	STAT	-	STAT
Tenecteplase	IV	Alternative thrombolytic for acute posterior circulation stroke; single bolus dosing	0.25 mg/kg :: IV :: once (max 25 mg) :: 0.25 mg/kg IV bolus (max 25 mg); single dose; emerging evidence for posterior circulation	Active hemorrhage; recent surgery; INR >1.7; platelets <100,000; BP >185/110; see full stroke exclusion criteria	BP q15min x 2h, then q30min x 6h, then q1h x 16h; neuro checks q15min during infusion; NIHSS; signs of hemorrhage	STAT	STAT	-	STAT
Dexamethasone	IV	Vasogenic edema from cerebellar mass (tumor, abscess); NOT for cytotoxic edema (stroke)	10 mg :: IV :: load, then 4 mg q6h :: 10 mg IV loading dose, then 4 mg IV q6h; for tumor/abscess-related edema only	Active GI bleeding; uncontrolled infection (relative); avoid in stroke	Blood glucose q6h; GI prophylaxis (PPI); mood changes; insomnia	STAT	STAT	-	STAT
Mannitol	IV	Elevated ICP from posterior fossa mass effect with impending herniation; cerebellar stroke with edema	1 g/kg :: IV :: bolus, then 0.25-0.5 g/kg q6h PRN :: 1 g/kg IV bolus over 15-20 min; then 0.25-0.5 g/kg q6h PRN; target serum osmolality <320	Severe dehydration; anuria; pulmonary edema	Serum osmolality q6h (hold if >320); BMP q6h; urine output; neuro exam	STAT	STAT	-	STAT
Hypertonic saline (23.4%)	IV	Acute ICP crisis from posterior fossa mass effect when rapid osmotic effect needed	30 mL :: IV :: bolus over 10-15 min :: 30 mL of 23.4% NaCl IV over 10-15 min via central line; may repeat if needed	Severe hypernatremia (Na >160); CHF	Serum sodium q4-6h (target 145-155); central line required for 23.4%; serum osmolality	STAT	STAT	-	STAT
Phenytoin dose adjustment or discontinuation	IV/PO	Phenytoin toxicity causing cerebellar ataxia (most common drug-induced cause); supratherapeutic level	N/A :: IV/PO :: per level :: Hold phenytoin; recheck level in 24-48h; resume at lower dose or switch to alternative AED; chronic toxicity may cause permanent cerebellar damage	Do not abruptly discontinue if on for seizures — taper and bridge	Repeat phenytoin level q12-24h until therapeutic; monitor for seizure breakthrough if reducing dose	STAT	STAT	ROUTINE	STAT
Lithium dose adjustment or discontinuation	PO	Lithium toxicity causing cerebellar ataxia; supratherapeutic level	N/A :: PO :: per level :: Hold lithium; aggressive IV hydration; recheck level q6-12h; hemodialysis if level >4.0 or severe symptoms; resume at lower dose when level therapeutic	Psychiatry consult before discontinuation; monitor for rebound mania	Lithium level q6-12h; BMP q6-12h; renal function; neurologic exam; hemodialysis if level >4.0	STAT	STAT	-	STAT

3B. Symptomatic Treatments¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Acetazolamide	PO	Episodic ataxia type 2 (EA2, CACNA1A mutation); first-line preventive therapy; reduces frequency and severity of episodes	250 mg :: PO :: BID :: Start 250 mg BID; titrate to 250-500 mg BID-TID based on response; max 1000 mg/day	Sulfonamide allergy; severe hepatic or renal impairment; metabolic acidosis; hypokalemia	BMP q3 months (metabolic acidosis, hypokalemia); renal function; paresthesias (common, benign); kidney stones (hydration)	-	ROUTINE	ROUTINE	-
4-Aminopyridine (dalfampridine)	PO	Episodic ataxia type 2; downbeat nystagmus; cerebellar gait ataxia; improves Purkinje cell function	5 mg :: PO :: BID :: Start 5 mg BID; may increase to 10 mg BID; 12 hours apart; max 20 mg/day	Seizure history (lowers seizure threshold); moderate-severe renal impairment (CrCl <50); concurrent use of other forms of 4-AP	Seizure risk; renal function at baseline and periodically; GI side effects	-	ROUTINE	ROUTINE	-
Riluzole	PO	Some spinocerebellar ataxias (SCA); neuroprotective; modest evidence for ataxia improvement in selected patients	50 mg :: PO :: BID :: 50 mg PO BID; take on empty stomach (1 hour before or 2 hours after meals)	Hepatic impairment (ALT >5x ULN); pregnancy	LFTs monthly x 3 months, then q3 months for first year, then periodically; neutrophil count; nausea, asthenia	-	-	ROUTINE	-
Amantadine	PO	Cerebellar ataxia (various etiologies); modest evidence for gait improvement; anti-glutamatergic properties	100 mg :: PO :: daily :: Start 100 mg daily; increase to 100 mg BID-TID over 1-2 weeks; max 300 mg/day; avoid afternoon dosing (insomnia)	Severe renal impairment (dose adjust if CrCl <50); seizure history; livedo reticularis; angle-closure glaucoma	Renal function; hallucinations (especially elderly); insomnia; livedo reticularis; ankle edema	-	ROUTINE	ROUTINE	-
Buspirone	PO	Cerebellar ataxia (various etiologies); serotonergic mechanism may improve cerebellar function; modest evidence	5 mg :: PO :: TID :: Start 5 mg TID; increase by 5 mg/dose q3-5 days; target 30-60 mg/day divided TID; max 60 mg/day	Concurrent MAOIs; severe hepatic or renal impairment	Dizziness; headache; nausea (usually transient); no dependence risk unlike benzodiazepines	-	ROUTINE	ROUTINE	-
Gabapentin	PO	Neuropathic pain in sensory ataxia; proprioceptive neuropathy symptoms; cerebellar tremor	300 mg :: PO :: qHS :: Start 300 mg qHS; titrate by 300 mg q3d; target 900-1800 mg/day divided TID; max 3600 mg/day; adjust for renal function	Severe renal impairment (dose adjust); respiratory depression with opioids or CNS depressants	Sedation; dizziness; peripheral edema; renal function; suicidality (rare); respiratory depression if combined with CNS depressants	-	ROUTINE	ROUTINE	-
Pregabalin	PO	Neuropathic pain in sensory ataxia; may help cerebellar tremor	75 mg :: PO :: BID :: Start 75 mg BID; increase to 150 mg BID after 1 week; max 600 mg/day; adjust for renal function	Severe renal impairment (dose adjust); angioedema history	Sedation; dizziness; weight gain; peripheral edema; renal function	-	ROUTINE	ROUTINE	-
Clonazepam	PO	Cerebellar tremor; myoclonus in progressive myoclonic ataxia; action tremor refractory to other treatments	0.25 mg :: PO :: BID :: Start 0.25 mg BID; increase by 0.25 mg q3-5 days; target 0.5-2 mg/day; max 4 mg/day; use lowest effective dose	Respiratory insufficiency; severe hepatic impairment; acute narrow-angle glaucoma; avoid abrupt discontinuation	Sedation; respiratory depression; dependence (limit duration); fall risk; cognitive impairment; paradoxical agitation (elderly)	-	ROUTINE	ROUTINE	-
Propranolol	PO	Cerebellar action tremor (kinetic/intention tremor component); reduces tremor amplitude	20 mg :: PO :: BID :: Start 20 mg BID; titrate by 20 mg/dose q1 week; max 320 mg/day; use LA formulation for once-daily dosing	Asthma/severe COPD (non-selective beta-blocker); bradycardia (HR <50); AV block (2nd/3rd degree); decompensated heart failure; severe peripheral vascular disease	Heart rate; blood pressure; blood glucose (masks hypoglycemia in diabetics); fatigue; depression	-	ROUTINE	ROUTINE	-
Ondansetron	IV/PO	Nausea and vomiting associated with acute cerebellar dysfunction and vertigo	4 mg :: IV/PO :: q8h PRN :: 4-8 mg IV/PO q8h PRN nausea; max 24 mg/day	QT prolongation; severe hepatic impairment (max 8 mg/day)	QTc if risk factors; constipation; headache	STAT	STAT	ROUTINE	STAT
Meclizine	PO	Vestibular symptoms (vertigo, nausea) associated with cerebellar ataxia; short-term use only	25 mg :: PO :: q6-8h PRN :: 25 mg PO q6-8h PRN; short-term use only (48-72h); do NOT use chronically — delays vestibular compensation	Elderly (anticholinergic effects); urinary retention; glaucoma	Sedation; anticholinergic effects; discontinue within 72 hours; does not treat underlying cause	STAT	STAT	-	-
Modafinil	PO	Fatigue associated with chronic cerebellar disease; daytime somnolence from medications or disease	100 mg :: PO :: daily :: Start 100 mg each morning; may increase to 200 mg daily; take before noon to avoid insomnia	Severe hepatic impairment; history of left ventricular hypertrophy; arrhythmia	Blood pressure; heart rate; insomnia; headache; may reduce efficacy of hormonal contraceptives	-	-	ROUTINE	-
Sertraline	PO	Depression and anxiety commonly comorbid with chronic ataxia; does not worsen ataxia	25 mg :: PO :: daily :: Start 25 mg daily; increase by 25 mg q1-2 weeks; target 50-150 mg daily; max 200 mg/day	Concurrent MAOIs (14-day washout); concurrent pimozide	Suicidality (especially first 4 weeks); serotonin syndrome; GI upset; sexual dysfunction; hyponatremia (elderly)	-	ROUTINE	ROUTINE	-

3C. Second-line/Refractory (Etiology-Specific Treatments)¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
IV methylprednisolone	IV	Autoimmune cerebellar ataxia (anti-GAD, paraneoplastic); MS cerebellar relapse; acute inflammatory cerebellitis	1000 mg :: IV :: daily x 3-5 days :: 1000 mg IV daily for 3-5 days; infuse over 1 hour; may follow with oral prednisone taper	Active infection; uncontrolled diabetes; GI bleeding; psychosis	Blood glucose q6h; blood pressure; mood/sleep; GI prophylaxis (PPI); potassium	-	STAT	-	-
IVIG (intravenous immunoglobulin)	IV	Autoimmune cerebellar ataxia (anti-GAD); paraneoplastic cerebellar degeneration; Miller Fisher syndrome (GBS variant with ataxia); post-infectious cerebellitis	0.4 g/kg :: IV :: daily x 5 days :: 0.4 g/kg/day IV for 5 days (total 2 g/kg); infuse slowly — start 0.5 mL/kg/h, increase to max 4 mL/kg/h; premedicate with acetaminophen and diphenhydramine	IgA deficiency (anaphylaxis risk — check IgA level); severe renal impairment; hypercoagulable state	Renal function (BMP before and after); headache (aseptic meningitis); thrombotic events; infusion reactions; vital signs during infusion	-	URGENT	-	-
Plasma exchange (PLEX)	IV	Autoimmune cerebellar ataxia refractory to steroids/IVIG; Miller Fisher syndrome; paraneoplastic cerebellar degeneration (limited benefit once neuronal loss established)	1-1.5 plasma volumes :: IV :: q other day x 5-7 exchanges :: 5-7 exchanges over 10-14 days; 1-1.5 plasma volumes per exchange; albumin replacement	Hemodynamic instability; active infection; severe coagulopathy	Electrolytes (calcium, magnesium) q exchange; fibrinogen; blood pressure; line complications; infection	-	URGENT	-	-
Rituximab	IV	Refractory autoimmune cerebellar ataxia (anti-GAD, other antibody-mediated); gluten ataxia not responding to diet; MS cerebellar involvement	1000 mg :: IV :: day 0 and day 14 :: 1000 mg IV on day 0 and day 14; repeat q6 months based on response or CD19/CD20 counts; premedicate with methylprednisolone, acetaminophen, diphenhydramine	Active hepatitis B (check HBsAg, anti-HBc before); active severe infection; severe heart failure	CBC with differential q3 months; immunoglobulin levels q6 months; hepatitis B reactivation screening; PML risk (rare); infusion reactions	-	ROUTINE	ROUTINE	-
Mycophenolate mofetil	PO	Steroid-sparing agent for chronic autoimmune cerebellar ataxia; maintenance immunosuppression	500 mg :: PO :: BID :: Start 500 mg BID; increase to 1000 mg BID after 2 weeks; max 3000 mg/day (rarely needed)	Pregnancy (Category D — teratogenic); active infection; hypersensitivity	CBC q2 weeks x 3 months, then monthly; LFTs monthly; renal function; GI symptoms (diarrhea, nausea); infections; live vaccines contraindicated	-	ROUTINE	ROUTINE	-
Azathioprine	PO	Alternative steroid-sparing agent for autoimmune cerebellar ataxia; TPMT testing required	50 mg :: PO :: daily :: Check TPMT before starting; start 50 mg daily; increase by 25 mg q2 weeks to target 2-2.5 mg/kg/day based on TPMT activity	TPMT deficiency (severe myelosuppression); concurrent allopurinol (reduce dose by 75%); pregnancy	CBC weekly x 4 weeks, then q2 weeks x 3 months, then monthly; LFTs monthly; TPMT genotype/phenotype before starting; infections; lymphoma risk (long-term)	-	ROUTINE	ROUTINE	-
Gluten-free diet	Dietary	Gluten ataxia (positive anti-gliadin antibodies); strict adherence required for benefit; improvement may take 6-12 months	N/A :: Dietary :: continuous :: Complete elimination of wheat, barley, rye, and cross-contaminated oats; dietitian referral essential; compliance monitoring with repeat anti-gliadin antibodies	None	Anti-gliadin antibody levels q6 months (should decrease with compliance); clinical ataxia scores (SARA, ICARS); nutritional status; B12 and iron	-	ROUTINE	ROUTINE	-
Coenzyme Q10 (CoQ10)	PO	CoQ10 deficiency (primary cerebellar ataxia responsive to supplementation); may benefit some mitochondrial ataxias	300 mg :: PO :: BID :: Start 300 mg BID; increase to 600 mg BID if tolerated and deficiency confirmed; take with fatty meal for absorption; may take months for improvement	None significant	Clinical ataxia scores; CoQ10 levels if available; GI tolerance; well-tolerated	-	ROUTINE	ROUTINE	-
Vitamin B12 supplementation	IM/PO	B12 deficiency causing sensory ataxia (subacute combined degeneration); posterior column disease	1000 mcg :: IM :: daily x 7 days :: 1000 mcg IM daily x 7 days, then weekly x 4 weeks, then monthly indefinitely; or high-dose oral 1000-2000 mcg daily if absorption adequate	None	B12 level at 2 months; MMA for adequacy of replacement; neurologic exam; CBC (reticulocyte response); sensory exam improvement may take months	URGENT	URGENT	ROUTINE	-
Vitamin E supplementation	PO	Vitamin E deficiency ataxia (abetalipoproteinemia, fat malabsorption); treatable cause	800 IU :: PO :: daily :: 800-1200 IU daily; higher doses may be needed in malabsorption syndromes; take with fatty meal	Caution with anticoagulants (may increase bleeding risk at high doses)	Vitamin E levels q3 months initially; PT/INR if on anticoagulants; clinical ataxia assessment	-	ROUTINE	ROUTINE	-
Copper supplementation	PO/IV	Copper deficiency myelopathy and ataxia (zinc excess, bariatric surgery, malabsorption)	2 mg :: PO/IV :: daily :: Acute: 2 mg IV daily x 5 days; Maintenance: 2 mg PO daily; remove cause (e.g., stop excess zinc)	Wilson disease (must be excluded before copper supplementation)	Serum copper and ceruloplasmin q3 months; zinc levels; CBC (copper deficiency causes anemia, neutropenia); neurologic exam	-	URGENT	ROUTINE	-
Idebenone	PO	Friedreich ataxia — may reduce cardiac hypertrophy; limited evidence for neurological benefit; investigational	5 mg/kg :: PO :: TID :: 5 mg/kg TID (typically 150-300 mg TID); take with food; not FDA-approved but used off-label	None significant	Cardiac function (echocardiogram); LFTs; clinical ataxia scores; well-tolerated	-	-	EXT	-
Omaveloxolone (Skyclarys)	PO	Friedreich ataxia — FDA-approved Nrf2 activator; first approved therapy for Friedreich ataxia (2023)	150 mg :: PO :: daily :: 150 mg PO once daily on empty stomach (1 hour before first meal); swallow capsule whole	Moderate-to-severe hepatic impairment; avoid strong CYP3A4 inhibitors; concurrent hepatotoxic drugs	LFTs at baseline, monthly x 3 months, then q3 months; BNP (cardiac); weight; clinical ataxia scores (mFARS)	-	-	ROUTINE	-

3D. Disease-Modifying or Chronic Therapies¶

Treatment	Route	Indication	Dosing	Pre-Treatment Requirements	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Rituximab (maintenance)	IV	Long-term immunosuppression for autoimmune cerebellar ataxia (anti-GAD, CASPR2, other autoantibodies)	1000 mg :: IV :: q6 months :: 1000 mg IV q6 months; adjust interval based on CD19/CD20 B cell counts and clinical response	HBsAg, anti-HBc, anti-HBs; quantitative immunoglobulins; CBC; LFTs; pregnancy test; vaccination update (live vaccines >4 weeks before)	Active hepatitis B; active severe infection; pregnancy; severe immunodeficiency	CD19/CD20 counts before each infusion; immunoglobulin levels q6 months; CBC q3 months; infections; PML screening (JCV risk very low with rituximab)	-	-	ROUTINE	-
Mycophenolate mofetil (maintenance)	PO	Steroid-sparing maintenance for chronic autoimmune cerebellar ataxia	1000 mg :: PO :: BID :: 1000 mg BID; dose adjust based on CBC and GI tolerance	CBC; LFTs; renal function; pregnancy test (teratogenic); TPMT not required for mycophenolate	Pregnancy (Category D); active infection; live vaccines	CBC monthly; LFTs q3 months; renal function q3 months; GI tolerance; infections; malignancy surveillance (skin exam annually)	-	-	ROUTINE	-
Azathioprine (maintenance)	PO	Alternative steroid-sparing maintenance for autoimmune cerebellar ataxia	2-2.5 mg/kg :: PO :: daily :: Target 2-2.5 mg/kg/day divided daily or BID; dose based on TPMT activity	TPMT genotype/phenotype; CBC; LFTs; renal function	TPMT deficiency; concurrent allopurinol (dose reduce 75%); pregnancy	CBC q2 weeks x 3 months, then monthly; LFTs monthly; infections; lymphoma risk (long-term); annual skin exam	-	-	ROUTINE	-

4. OTHER RECOMMENDATIONS¶

4A. Referrals & Consults¶

Recommendation	ED	HOSP	OPD	ICU
Neurology consultation for ataxia evaluation, localization (cerebellar vs. sensory), and diagnostic workup guidance	URGENT	URGENT	ROUTINE	URGENT
Movement disorders specialist referral for chronic or progressive ataxia requiring specialized evaluation and genetic testing interpretation	-	ROUTINE	ROUTINE	-
Stroke neurology consultation if acute cerebellar stroke suspected based on sudden onset, vascular risk factors, or central exam findings	STAT	STAT	-	STAT
Physical therapy for gait training, balance exercises, fall prevention, and adaptive strategies for progressive ataxia	-	ROUTINE	ROUTINE	-
Occupational therapy for fine motor training, adaptive equipment (weighted utensils, writing aids), and ADL modifications	-	ROUTINE	ROUTINE	-
Speech therapy for cerebellar dysarthria (scanning speech) evaluation and treatment; swallow evaluation if dysphagia present	-	ROUTINE	ROUTINE	-
Genetic counseling referral when hereditary ataxia (SCA, Friedreich, EA) is confirmed or suspected based on family history or genetic testing results	-	-	ROUTINE	-
Cardiology referral for Friedreich ataxia (cardiomyopathy screening) or MSA-C (autonomic cardiovascular dysfunction)	-	ROUTINE	ROUTINE	-
Neurosurgery consultation for posterior fossa mass lesion, large cerebellar stroke with mass effect, or obstructive hydrocephalus requiring intervention	STAT	STAT	-	STAT
Oncology referral for paraneoplastic cerebellar degeneration with identified or suspected malignancy	-	URGENT	URGENT	-
Psychiatry referral for depression or anxiety management in chronic progressive ataxia affecting quality of life	-	ROUTINE	ROUTINE	-
Dietitian referral for gluten-free diet implementation in gluten ataxia; nutritional assessment in malabsorption-related ataxia	-	ROUTINE	ROUTINE	-
Social work for disability resources, adaptive equipment funding, home safety assessment, and caregiver support in progressive ataxia	-	ROUTINE	ROUTINE	-
Palliative care referral for advanced degenerative ataxia (MSA-C, advanced SCA) for symptom management and goals of care discussion	-	ROUTINE	ROUTINE	-

4B. Patient Instructions¶

Recommendation	ED	HOSP	OPD	ICU
Return immediately for sudden worsening of ataxia, new headache, vomiting, or change in consciousness (may indicate stroke or mass lesion requiring emergency treatment)	STAT	STAT	ROUTINE	-
Return immediately for new double vision, slurred speech, weakness, or numbness (may indicate brainstem or cerebellar stroke)	STAT	STAT	ROUTINE	-
Do not drive until cleared by neurology due to impaired coordination and fall risk affecting vehicle control	ROUTINE	ROUTINE	ROUTINE	-
Use assistive devices (walker, cane) as recommended by physical therapy to prevent falls and injury	-	ROUTINE	ROUTINE	-
Remove tripping hazards at home (rugs, clutter, poor lighting) and install grab bars in bathroom to reduce fall risk	-	ROUTINE	ROUTINE	-
Do not stop or adjust seizure medications (phenytoin, carbamazepine) without physician guidance as this may cause breakthrough seizures	ROUTINE	ROUTINE	ROUTINE	-
Avoid alcohol as it worsens cerebellar function and may cause permanent cerebellar damage with chronic use	ROUTINE	ROUTINE	ROUTINE	-
For gluten ataxia: strictly avoid all wheat, barley, rye, and cross-contaminated products; improvement may take 6-12 months of strict adherence	-	ROUTINE	ROUTINE	-
Keep a symptom diary tracking episode frequency, duration, and triggers for episodic ataxia to guide treatment optimization	-	-	ROUTINE	-
Genetic testing results may have implications for family members; discuss with genetic counselor before sharing results	-	-	ROUTINE	-

4C. Lifestyle & Prevention¶

Recommendation	ED	HOSP	OPD	ICU
Alcohol cessation to prevent further cerebellar damage and reduce ongoing cerebellar toxicity (alcohol-related cerebellar degeneration primarily affects anterior vermis)	ROUTINE	ROUTINE	ROUTINE	-
Smoking cessation to reduce vascular risk factors for posterior circulation stroke and overall health improvement	-	ROUTINE	ROUTINE	-
Regular exercise program adapted to balance limitations (swimming, stationary bike, seated exercises) to maintain strength and cardiovascular health	-	ROUTINE	ROUTINE	-
Fall prevention strategies: adequate lighting, non-skid footwear, remove loose rugs, install handrails on both sides of stairs	-	ROUTINE	ROUTINE	-
Strict glycemic control (HbA1c <7%) if diabetic neuropathy contributing to sensory ataxia component	-	ROUTINE	ROUTINE	-
Mediterranean diet for vascular risk reduction in stroke-related ataxia; adequate nutrition in malabsorption-related ataxia	-	ROUTINE	ROUTINE	-
Vitamin B12 and folate-rich diet (meat, fish, dairy, leafy greens) to support nerve health and prevent deficiency-related ataxia	-	ROUTINE	ROUTINE	-
Weight management to reduce joint stress and improve mobility in patients with gait ataxia	-	-	ROUTINE	-
Stress management and adequate sleep (7-9 hours) as stress and fatigue may worsen ataxia symptoms and trigger episodic ataxia attacks	-	-	ROUTINE	-
Medic alert bracelet recommended for patients with episodic ataxia (may appear intoxicated during episodes) or Friedreich ataxia (cardiac risk)	-	-	ROUTINE	-

=============================================================== SECTION B: SUPPORTING INFORMATION ===============================================================

5. DIFFERENTIAL DIAGNOSIS¶

Ataxia Classification by Tempo¶

Tempo	Etiologies	Key Distinguishing Features	Tests to Differentiate
Acute (hours-days)	Posterior fossa stroke (cerebellar infarct/hemorrhage), drug toxicity (phenytoin, lithium, alcohol), Wernicke encephalopathy, post-infectious cerebellitis, acute MS relapse, basilar migraine	Sudden onset; vascular risk factors (stroke); medication history (toxic); triad of ataxia/ophthalmoplegia/confusion (Wernicke); recent viral illness (post-infectious); prior MS or demyelinating events	CT head (hemorrhage); MRI DWI (stroke); drug levels; thiamine level; MRI with contrast (MS)
Subacute (weeks-months)	Paraneoplastic cerebellar degeneration, autoimmune (anti-GAD), gluten ataxia, vitamin deficiency (B12, E, thiamine), prion disease (CJD), CNS lymphoma, brain abscess	Progressive over weeks; weight loss/smoking (paraneoplastic); GI symptoms (gluten/celiac); dietary history (B12/E); rapid cognitive decline (CJD); fever/immunosuppression (abscess)	Paraneoplastic panel; anti-GAD; anti-gliadin; B12/E/thiamine; MRI; CSF (14-3-3, RT-QuIC for CJD)
Chronic (months-years)	Hereditary (SCA types, Friedreich, EA, AT), degenerative (MSA-C), alcoholic cerebellar degeneration, chronic drug exposure, idiopathic late-onset cerebellar ataxia	Family history (hereditary); progressive over years; autonomic failure (MSA-C); heavy alcohol use history; chronic medication exposure; anterior vermis atrophy on MRI (alcohol)	Genetic testing (SCA panel, Friedreich); MRI (atrophy pattern); autonomic testing (MSA); alcohol history
Episodic (discrete attacks)	Episodic ataxia type 1 (EA1), episodic ataxia type 2 (EA2), vestibular migraine, TIA (vertebrobasilar), metabolic decompensation	Attacks lasting minutes (EA1) or hours (EA2); myokymia between attacks (EA1); nystagmus between attacks (EA2); migraine features; vascular risk factors (TIA)	Genetic testing (KCNA1 for EA1, CACNA1A for EA2); MRI/MRA; headache history

Cerebellar vs. Sensory Ataxia¶

Feature	Cerebellar Ataxia	Sensory Ataxia
Romberg sign	Negative or mildly positive (unsteady with eyes open AND closed)	Strongly positive (markedly worse with eyes closed)
Proprioception	Normal	Impaired (loss of vibration and position sense)
Deep tendon reflexes	Variable (may be normal or decreased)	Decreased or absent
Dysmetria	Present (finger-to-nose, heel-to-shin)	Absent or mild
Nystagmus	Present (gaze-evoked, downbeat, or positional)	Absent
Dysarthria	Scanning/explosive speech	Normal speech
Gait	Wide-based, irregular, cannot tandem walk	Wide-based, stamping gait, worse in dark/eyes closed
Pseudoathetosis	Absent	Present (involuntary writhing of outstretched fingers)
MRI finding	Cerebellar atrophy or lesion	Normal cerebellum; may show dorsal column signal change on spine MRI
Common causes	Stroke, alcohol, SCA, MSA-C, paraneoplastic, autoimmune	B12 deficiency, sensory neuropathy, dorsal column lesion, tabes dorsalis, Friedreich ataxia

Key Cerebellar Atrophy Patterns on MRI¶

Pattern	Etiology
Anterior vermis atrophy	Alcohol-related cerebellar degeneration (classic pattern)
Global cerebellar atrophy	SCA types, MSA-C, paraneoplastic
Hemispheric atrophy (unilateral)	Prior stroke; focal lesion; post-radiation
Pontocerebellar atrophy	MSA-C (hot cross bun sign in pons on MRI); SCA1, SCA2, SCA7
No atrophy (early stage)	Early paraneoplastic; acute causes; episodic ataxia

Common Paraneoplastic Antibodies in Cerebellar Degeneration¶

Antibody	Associated Malignancy	Notes
Anti-Yo (PCA-1)	Ovarian cancer, breast cancer	Most common paraneoplastic cerebellar antibody; poor neurological recovery
Anti-Hu (ANNA-1)	Small cell lung cancer	Often with sensory neuropathy (sensory ataxia + cerebellar)
Anti-Tr (DNER)	Hodgkin lymphoma	Good neurological recovery if lymphoma treated early
Anti-mGluR1	Hodgkin lymphoma	Rare; good response to tumor treatment
Anti-CV2/CRMP5	Small cell lung cancer, thymoma	Mixed neuropathy + cerebellar syndrome
Anti-VGCC (P/Q type)	Small cell lung cancer	Often with Lambert-Eaton syndrome
Anti-amphiphysin	Breast cancer, small cell lung cancer	Often with stiff-person spectrum

6. MONITORING PARAMETERS¶

Parameter	Frequency	Target/Threshold	Action if Abnormal	ED	HOSP	OPD	ICU
Neurologic exam (cerebellar signs, gait, coordination)	Each visit; q8h if acute	Stable or improving	Worsening → repeat imaging; reassess diagnosis; adjust treatment	STAT	ROUTINE	ROUTINE	STAT
SARA score (Scale for Assessment and Rating of Ataxia)	Baseline, then q3-6 months	Stable or improving score	Progressive worsening → reassess etiology; intensify treatment/rehabilitation	-	ROUTINE	ROUTINE	-
Drug levels (phenytoin, lithium, carbamazepine)	At presentation if on these medications; then per drug monitoring schedule	Therapeutic range	Supratherapeutic → dose adjustment; discontinue if persistent cerebellar toxicity	STAT	ROUTINE	ROUTINE	STAT
MRI brain	Baseline; repeat at 6-12 months for progressive ataxia; earlier if worsening	Stable; no new lesions; atrophy pattern unchanged	New lesion → reassess diagnosis; progressive atrophy → adjust management	-	URGENT	ROUTINE	-
Blood glucose (on high-dose steroids)	q6h during IV steroids; QID during oral taper	140-180 mg/dL inpatient	>200 → sliding scale insulin; endocrinology if persistent	-	ROUTINE	ROUTINE	ROUTINE
CBC (on immunosuppressive therapy)	q2 weeks x 3 months, then monthly (azathioprine/mycophenolate); q3 months (rituximab)	WBC >3000; ANC >1500; platelets >100,000	Cytopenias → hold or reduce immunosuppression; infection evaluation	-	ROUTINE	ROUTINE	-
LFTs (on riluzole, immunosuppressants)	Monthly x 3 months, then q3 months (riluzole); monthly (azathioprine/mycophenolate)	ALT/AST <3x ULN	Elevated >3x → reduce dose; >5x → discontinue	-	ROUTINE	ROUTINE	-
Renal function (on immunotherapy, aminopyridine)	At baseline, then q3-6 months	Normal GFR	Declining → adjust renally-cleared medications (aminopyridine, gabapentin, pregabalin)	-	ROUTINE	ROUTINE	-
Immunoglobulin levels (on rituximab)	q6 months	IgG >500 mg/dL	Low IgG → supplement with IVIG; evaluate infection risk	-	ROUTINE	ROUTINE	-
Echocardiogram (Friedreich ataxia)	At diagnosis, then annually	No cardiomyopathy progression	LV hypertrophy or dysfunction → cardiology management; adjust exercise restrictions	-	ROUTINE	ROUTINE	-
HbA1c (Friedreich ataxia)	q6 months	<7.0%	Elevated → diabetes management; Friedreich ataxia has high rate of glucose intolerance/diabetes	-	ROUTINE	ROUTINE	-
Anti-gliadin antibodies (gluten ataxia)	q6 months after starting gluten-free diet	Decreasing titers	Persistent elevation → assess dietary compliance; dietitian reinforcement	-	-	ROUTINE	-
Fall risk assessment	Each visit	No falls	Recurrent falls → PT reassessment; home safety evaluation; assistive device upgrade	-	ROUTINE	ROUTINE	-
Swallowing function	At baseline if dysarthria present; repeat if worsening	Safe oral intake	Dysphagia → modified diet; speech therapy; PEG placement if severe (advanced disease)	-	ROUTINE	ROUTINE	-

7. DISPOSITION CRITERIA¶

Disposition	Criteria
Discharge home	Clear etiology identified (drug toxicity with drug held, BPPV treated, B12 initiated); stable neurologic exam; safe ambulation (with or without assistive device); able to tolerate oral medications; outpatient follow-up arranged with neurology; no red flags for central cause
Admit to floor	New subacute ataxia requiring expedited workup (paraneoplastic panel, autoimmune labs, MRI with contrast); acute ataxia with diagnostic uncertainty; intractable nausea/vomiting requiring IV fluids and antiemetics; initiation of IV immunotherapy (steroids, IVIG); unsafe ambulation with high fall risk and inadequate home support
Admit to ICU / Stroke unit	Acute posterior fossa stroke (cerebellar infarction or hemorrhage); posterior fossa mass with mass effect or hydrocephalus; Wernicke encephalopathy with altered consciousness; basilar artery occlusion; need for emergent neurosurgical intervention (posterior fossa decompression, EVD)
Transfer to higher level of care	Posterior fossa stroke or mass requiring neurosurgical capability not available at current facility; need for endovascular intervention (basilar artery thrombectomy); need for specialized neurocritical care
Outpatient follow-up	Neurology follow-up in 2-4 weeks for chronic ataxia evaluation results; movement disorders follow-up in 4-8 weeks for genetic testing results; PCP within 1-2 weeks for medication adjustment; PT/OT within 1 week for ongoing rehabilitation

8. EVIDENCE & REFERENCES¶

Key Guidelines¶

Guideline	Source	Year	Key Recommendation
Approach to the Patient with Chronic Progressive Ataxia	Manto & Marmolino. Cerebellum 2009	2009	Systematic evaluation approach including history, exam, imaging, labs, and genetic testing
AAN Practice Parameter: Evaluation of Ataxia	Fogel & Perlman. Neurology 2007	2007	Genetic testing algorithm based on clinical features; MRI as first-line imaging
European Guidelines for Spinocerebellar Ataxias	van de Warrenburg et al. Eur J Neurol 2014	2014	Diagnostic approach and management of hereditary cerebellar ataxias
Treatment of Degenerative Ataxias	Zesiewicz et al. Neurology 2018	2018	AAN guideline update on pharmacotherapy for degenerative ataxias; riluzole and aminopyridine evidence

Landmark Studies and Key Evidence¶

Recommendation	Evidence Level	Source
Paraneoplastic cerebellar degeneration — early tumor treatment improves outcomes	Class III, Level C	Shams'ili et al. Brain 2003
Anti-GAD antibodies in autoimmune cerebellar ataxia — high titers (>2000 IU/mL) associated with cerebellar syndrome	Class III, Level C	Honnorat et al. Brain 2001
Gluten ataxia — anti-gliadin antibodies in sporadic ataxia; response to gluten-free diet	Class III, Level C	Hadjivassiliou et al. Lancet 1998
Gluten ataxia — most common cause of sporadic ataxia; anti-gliadin prevalence	Class III, Level C	Hadjivassiliou et al. Brain 2003
4-Aminopyridine effective for episodic ataxia type 2 and downbeat nystagmus	Class I, Level B	Strupp et al. Neurology 2011
Riluzole for cerebellar ataxia — moderate improvement in SARA scores across mixed ataxia etiologies	Class I, Level B	Romano et al. Lancet Neurol 2015
Acetazolamide for episodic ataxia type 2 — reduces episode frequency and severity	Class III, Level C	Griggs et al. Ann Neurol 1978
Omaveloxolone (Skyclarys) — FDA-approved for Friedreich ataxia; improved mFARS score	Class I, Level B	Lynch et al. N Engl J Med 2024
IVIG for autoimmune cerebellar ataxia (anti-GAD) — case series showing improvement	Class IV, Level C	Arino et al. JAMA Neurol 2014
Friedreich ataxia — natural history and cardiac involvement require surveillance	Class III, Level C	Pandolfo. Arch Neurol 2008
SARA scale — validated rating scale for cerebellar ataxia assessment and monitoring	Validation study	Schmitz-Hubsch et al. Neurology 2006
Alcohol-related cerebellar degeneration — anterior vermis atrophy pattern; abstinence may halt progression	Class III, Level C	Fitzpatrick et al. Eur Radiol 2008
MSA-C diagnostic criteria and natural history	Consensus criteria	Gilman et al. Neurology 2008
Thiamine replacement for Wernicke encephalopathy — IV thiamine prevents permanent cerebellar damage	Class III, Level C	Galvin et al. J Neurol Neurosurg Psychiatry 2010
Rituximab for autoimmune cerebellar ataxia — emerging evidence for anti-GAD and paraneoplastic	Class IV, Level C	Jarius et al. J Neuroimmunol 2010

CHANGE LOG¶

v1.1 (January 31, 2026) - Fixed structured dosing format across all treatment tables (3A, 3B, 3C, 3D) to standard [dose] :: [route] :: [frequency] :: [instructions] - Expanded cross-references to self-contained content: Tenecteplase contraindications/monitoring (was "Same as alteplase"); MRA/MR spectroscopy contraindications (was "Same as MRI") - Added ICU column to Sections 4A, 4B, 4C (Referrals, Patient Instructions, Lifestyle) - Added ICU column to Section 6 (Monitoring Parameters) - Added ICU coverage (STAT) for acute treatments in 3A: thiamine, alteplase, tenecteplase, dexamethasone, mannitol, hypertonic saline, phenytoin adjustment, lithium adjustment - Added ICU coverage (STAT) for core labs (1A): CBC, CMP, glucose, magnesium, drug levels, blood alcohol, urinalysis, thiamine, ESR/CRP, B12 - Added ICU coverage for essential imaging (2A): CT head (STAT), MRI brain (URGENT), MRA/CTA (URGENT) - Added ICU coverage for acute-relevant referrals (4A): neurology (URGENT), stroke neurology (STAT), neurosurgery (STAT) - Added ICU coverage for acute monitoring (Section 6): neurologic exam (STAT), drug levels (STAT), blood glucose on steroids (ROUTINE) - Updated frontmatter settings from "ED, HOSP, OPD" to "ED, HOSP, OPD, ICU" - Changed Gluten-free diet route from "PO" to "Dietary" for accuracy - Fixed directive language: "consider ICP management" → "initiate ICP management"; "consider IVIG supplementation" → "supplement with IVIG"; "consider PEG" → "PEG placement" - Fixed Lithium row: moved "Monitor for rebound mania" from Contraindications to properly note as "Psychiatry consult before discontinuation; monitor for rebound mania" - Standardized Phenytoin/Lithium adjustment dosing fields to use N/A for dose when action is dose-hold rather than administration - Fixed Buspirone starting dose field from "10 mg" to "5 mg" to match full instructions

v1.0 (January 30, 2026) - Initial template creation - Comprehensive 8-section format covering acute, subacute, and chronic ataxia - Full differential diagnosis tables (cerebellar vs. sensory; tempo-based; MRI atrophy patterns) - Complete treatment tables with structured dosing format - Evidence section with PubMed citation links - Settings: ED, HOSP, OPD (ICU marked "-" for most items)

APPENDIX A: Systematic Approach to Ataxia Evaluation¶

Step 1: Localize the Ataxia¶

Cerebellar ataxia: Dysmetria, intention tremor, dysdiadochokinesia, nystagmus, scanning speech, wide-based gait (NOT worse with eye closure)
Sensory ataxia: Positive Romberg, loss of proprioception/vibration, pseudoathetosis, stamping gait (WORSE with eye closure)
Mixed: Some conditions (Friedreich ataxia, MSA-C) involve both

Step 2: Determine Tempo¶

Acute (hours-days): Stroke, toxic, Wernicke, post-infectious
Subacute (weeks-months): Paraneoplastic, autoimmune, nutritional, CJD
Chronic (months-years): Hereditary, degenerative, alcoholic
Episodic (discrete attacks): Channelopathies (EA1, EA2), vestibular migraine, TIA

Step 3: Identify Key Clinical Features¶

Family history → hereditary (SCA, Friedreich, EA)
Cancer history or smoking → paraneoplastic
Alcohol use → alcoholic cerebellar degeneration
Medication use (phenytoin, lithium, carbamazepine) → drug toxicity
GI symptoms or weight loss → gluten ataxia, malabsorption
Autonomic failure → MSA-C
Cardiomyopathy + scoliosis + young onset → Friedreich ataxia
Telangiectasias + immunodeficiency → ataxia-telangiectasia
Ophthalmoplegia + confusion → Wernicke encephalopathy

Step 4: Order Investigations by Priority¶

STAT (ED): CT head (hemorrhage), drug levels, blood glucose, thiamine, blood alcohol
Urgent: MRI brain with DWI and contrast, essential labs (B12, CMP, TSH, ESR/CRP)
Routine: Anti-GAD, anti-gliadin, paraneoplastic panel, NCS/EMG, spine MRI
Extended: Genetic testing (SCA panel, Friedreich), whole exome, rare antibodies, metabolic studies

APPENDIX B: Hereditary Ataxia Quick Reference¶

Condition	Gene/Mutation	Inheritance	Age of Onset	Key Features
Friedreich ataxia	FXN (GAA expansion)	Autosomal recessive	5-25 years (classic)	Cardiomyopathy, scoliosis, diabetes, sensory neuropathy, absent DTRs, upgoing toes
SCA1	ATXN1 (CAG expansion)	Autosomal dominant	30-40 years	Cerebellar ataxia, ophthalmoparesis, pyramidal signs, peripheral neuropathy
SCA2	ATXN2 (CAG expansion)	Autosomal dominant	30-40 years	Slow saccades (hallmark), cerebellar ataxia, peripheral neuropathy, hyporeflexia
SCA3 (Machado-Joseph)	ATXN3 (CAG expansion)	Autosomal dominant	30-50 years	Most common SCA; cerebellar ataxia, ophthalmoplegia, pyramidal and extrapyramidal signs, faciolingual myokymia
SCA6	CACNA1A (CAG expansion)	Autosomal dominant	>50 years	Pure cerebellar; slowly progressive; downbeat nystagmus; episodic features early
SCA7	ATXN7 (CAG expansion)	Autosomal dominant	20-40 years	Retinal degeneration (visual loss, macular dystrophy) + cerebellar ataxia
Episodic ataxia type 1	KCNA1	Autosomal dominant	Childhood	Brief attacks (minutes); myokymia between attacks; responds to carbamazepine
Episodic ataxia type 2	CACNA1A	Autosomal dominant	Childhood-young adult	Attacks last hours; interictal nystagmus; responds to acetazolamide
Ataxia-telangiectasia	ATM	Autosomal recessive	1-4 years	Telangiectasias (conjunctival, ear, skin); immunodeficiency; elevated AFP; cancer predisposition
MSA-C	Not genetic (sporadic)	N/A	50-60 years	Rapidly progressive cerebellar ataxia + autonomic failure (orthostatic hypotension, urinary dysfunction); hot cross bun sign on MRI

This template represents the initial build phase and requires validation through the checker pipeline before clinical deployment.