Huntington's Disease¶

DIAGNOSIS: Huntington's Disease ICD-10: G10 (Huntington disease); F02.80 (Dementia in HD without behavioral disturbance); F02.81 (Dementia in HD with behavioral disturbance) SYNONYMS: Huntington's chorea, Huntington chorea, HD, hereditary chorea, chronic progressive chorea, Huntington disease, HTT-related disorder SCOPE: Diagnosis confirmation via genetic testing, chorea management, psychiatric symptom treatment, cognitive decline management, dysphagia assessment, genetic counseling, and end-of-life planning. Focuses primarily on outpatient management. Excludes Huntington disease-like syndromes (HDL1-4) and other chorea etiologies.

VERSION: 1.1 CREATED: January 27, 2026 REVISED: January 30, 2026 STATUS: Draft - Pending Review

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	ED	HOSP	OPD	ICU	Rationale	Target Finding
Huntington gene test (HTT CAG repeat) (CPT 81401)	-	ROUTINE	ROUTINE	-	Definitive diagnosis; CAG repeat expansion	≥36 CAG repeats diagnostic (40+ fully penetrant)
CBC (CPT 85025)	STAT	ROUTINE	ROUTINE	-	Baseline; anemia contributes to fatigue; infection screen	Normal
BMP (CPT 80048)	STAT	ROUTINE	ROUTINE	-	Electrolytes; renal function for medication dosing	Normal
Hepatic panel (LFTs) (CPT 80076)	-	ROUTINE	ROUTINE	-	Baseline before tetrabenazine/deutetrabenazine; valproate if used	Normal
TSH (CPT 84443)	-	ROUTINE	ROUTINE	-	Hypothyroidism can mimic apathy and cognitive slowing	Normal
Vitamin B12 (CPT 82607)	-	ROUTINE	ROUTINE	-	Deficiency can worsen cognitive and psychiatric symptoms	>300 pg/mL
Vitamin D, 25-hydroxy (CPT 82306)	-	ROUTINE	ROUTINE	-	Deficiency common; contributes to falls and bone health	>30 ng/mL

1B. Extended Workup (Second-line)¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Iron studies (CPT 83540), ferritin (CPT 82728)	-	ROUTINE	ROUTINE	-	Neurodegeneration with brain iron accumulation if HD-negative	Normal
Ceruloplasmin (CPT 82390), serum copper (CPT 82525)	-	EXT	ROUTINE	-	Wilson's disease if younger onset, HD gene-negative	Normal
ACTN3 gene test (CPT 81479)	-	-	EXT	-	Research; may modify age of onset	Research use
Acanthocyte screen (peripheral smear) (CPT 85060)	-	EXT	EXT	-	Chorea-acanthocytosis if HD gene-negative	No acanthocytes
Lipid panel (CPT 80061)	-	ROUTINE	ROUTINE	-	Cardiovascular risk; weight loss monitoring	Normal
Prealbumin (CPT 84134), albumin (CPT 82040)	-	ROUTINE	ROUTINE	-	Nutritional status assessment in advanced disease	Normal

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

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Genetic testing for HDL syndromes (PRNP, JPH3, TBP, ATN1) (CPT 81479)	-	-	EXT	-	HD-like phenotype with negative HTT test	Identifies HD-like syndrome
CSF biomarkers (neurofilament light chain) (CPT 83519)	-	-	EXT	-	Disease progression monitoring; research	Elevated in active disease
Kynurenine pathway metabolites (CPT 82542)	-	-	EXT	-	Research; therapeutic target assessment	Research use

2. DIAGNOSTIC IMAGING & STUDIES¶

2A. Essential/First-line¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
MRI Brain without contrast (CPT 70551)	URGENT	ROUTINE	ROUTINE	-	At diagnosis	Caudate atrophy; lateral ventricle enlargement ("boxcar" ventricles)	MRI-incompatible devices

2B. Extended¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
MRI Brain volumetric (CPT 70553)	-	-	ROUTINE	-	Baseline and annually for progression	Quantify caudate and striatal volume loss	MRI contraindications
Swallowing evaluation (VFSS or FEES) (CPT 74230/92612)	-	ROUTINE	ROUTINE	-	At diagnosis and with dysphagia symptoms	Identify aspiration risk; guide diet modification	None
ECG (CPT 93000)	-	ROUTINE	ROUTINE	-	Baseline before tetrabenazine/deutetrabenazine	QTc <450 ms	None
Polysomnography (CPT 95810)	-	-	ROUTINE	-	Sleep disturbance evaluation	Rule out sleep apnea; assess sleep architecture	None

2C. Rare/Specialized¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
PET imaging (FDG or specific tracers) (CPT 78816)	-	-	EXT	-	Research; atypical presentation	Striatal hypometabolism	None
Neuropsychological testing battery (CPT 96132)	-	-	ROUTINE	-	At diagnosis and annually	Baseline cognitive profile; monitor decline	None
Genetic modifier testing (research) (CPT 81479)	-	-	EXT	-	Prognosis; clinical trials	Identifies modifiers of age of onset	None

3. TREATMENT¶

3A. Acute/Emergent¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Lorazepam	IV/PO	Severe chorea causing injury or exhaustion	0.5 mg :: IV/PO :: PRN :: 0.5-2 mg IV/PO q4-6h PRN; short-term use only	Respiratory depression; acute narrow-angle glaucoma	Respiratory status, sedation	STAT	STAT	-	STAT
Haloperidol	IV/IM	Severe psychosis with agitation; acute behavioral emergency	2 mg :: IM :: PRN :: 2-5 mg IM; may repeat q4-6h; max 20 mg/day; transition to oral	QTc prolongation; history of NMS; worsens dystonia	ECG, EPS, sedation	STAT	STAT	-	STAT
Olanzapine	IM/PO	Acute agitation with psychosis; alternative to haloperidol	5 mg :: IM :: PRN :: 5-10 mg IM; may repeat in 2 hours; max 30 mg/day	Concurrent benzodiazepines (caution); diabetes	Glucose, sedation, EPS	STAT	STAT	-	STAT
IV fluids	IV	Dehydration from dysphagia or decreased oral intake	NS at 75 mL/hr :: IV :: continuous :: NS at 75-125 mL/hr; correct dehydration; transition to oral when safe	Fluid overload	I/O, electrolytes	STAT	STAT	-	STAT
Thiamine	IV	Nutritional deficiency; altered mental status	100 mg :: IV :: daily :: 100 mg IV daily x 3-5 days; then oral	None	None	STAT	STAT	-	STAT

3B. Symptomatic Treatments - Chorea¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Tetrabenazine (Xenazine)	PO	FDA-approved for HD chorea; first-line	12.5 mg :: PO :: daily :: Start 12.5 mg daily; increase by 12.5 mg q1wk; max 100 mg/day (25 mg per dose); CYP2D6 testing recommended	Active suicidality; untreated depression; concurrent MAOIs; hepatic impairment	Depression (PHQ-9 monthly), akathisia, parkinsonism, QTc	-	ROUTINE	ROUTINE	-
Deutetrabenazine (Austedo)	PO	FDA-approved for HD chorea; better tolerability than tetrabenazine	6 mg :: PO :: daily :: Start 6 mg daily; increase by 6 mg/wk; max 48 mg/day (24 mg per dose)	Active suicidality; untreated depression; concurrent MAOIs; hepatic impairment	Depression (PHQ-9 monthly), akathisia, parkinsonism, QTc	-	ROUTINE	ROUTINE	-
Valbenazine (Ingrezza)	PO	Off-label for HD chorea; once daily dosing	40 mg :: PO :: daily :: Start 40 mg daily; may increase to 80 mg after 1 week	Severe hepatic impairment; concurrent MAOIs; congenital long QT	Depression, akathisia, QTc prolongation	-	ROUTINE	ROUTINE	-
Risperidone	PO	Chorea with psychosis; antipsychotic with motor benefit	0.5 mg :: PO :: daily :: Start 0.5 mg daily; titrate by 0.5 mg q1wk; max 6 mg/day	QTc prolongation; history of NMS	EPS, metabolic panel, prolactin	-	ROUTINE	ROUTINE	-
Olanzapine	PO	Chorea with weight loss; promotes weight gain	2.5 mg :: PO :: daily :: Start 2.5-5 mg qHS; titrate to effect; typical 5-15 mg/day	Diabetes; significant metabolic risk	Weight, glucose, lipids	-	ROUTINE	ROUTINE	-
Clonazepam	PO	Adjunct for chorea; also helps myoclonus and anxiety	0.25 mg :: PO :: BID :: Start 0.25 mg BID; titrate slowly; max 4 mg/day	Severe respiratory disease; falls risk	Sedation, falls, cognitive effects	-	ROUTINE	ROUTINE	-
Amantadine	PO	Mild chorea; may help fatigue	100 mg :: PO :: daily :: Start 100 mg daily; titrate to 100 mg TID; max 400 mg/day	End-stage renal disease; seizure history	Livedo reticularis, hallucinations, edema	-	ROUTINE	ROUTINE	-

3C. Symptomatic Treatments - Psychiatric¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Sertraline	PO	Depression; anxiety; irritability	25 mg :: PO :: daily :: Start 25 mg daily; titrate by 25-50 mg q1-2wk; max 200 mg/day	MAOIs within 14 days	Suicidality, serotonin syndrome	-	ROUTINE	ROUTINE	-
Citalopram	PO	Depression; anxiety; good tolerability	10 mg :: PO :: daily :: Start 10 mg daily; max 20 mg/day due to QTc risk	QTc >500 ms; concurrent QT-prolonging drugs	QTc if risk factors	-	ROUTINE	ROUTINE	-
Escitalopram	PO	Depression; anxiety; similar to citalopram	5 mg :: PO :: daily :: Start 5-10 mg daily; max 20 mg/day	QTc >500 ms; concurrent QT-prolonging drugs	QTc if risk factors	-	ROUTINE	ROUTINE	-
Venlafaxine XR	PO	Depression with fatigue; dual mechanism	37.5 mg :: PO :: daily :: Start 37.5 mg daily; titrate q1wk; max 225 mg/day	Uncontrolled hypertension	BP at higher doses	-	ROUTINE	ROUTINE	-
Mirtazapine	PO	Depression with insomnia and weight loss; promotes appetite	7.5 mg :: PO :: qHS :: Start 7.5-15 mg qHS; titrate q1-2wk; max 45 mg	None significant	Weight, sedation	-	ROUTINE	ROUTINE	-
Quetiapine	PO	Psychosis; irritability; insomnia; less EPS than other antipsychotics	25 mg :: PO :: qHS :: Start 25 mg qHS; titrate by 25-50 mg q3d; typical 150-400 mg/day	Uncontrolled diabetes	Glucose, lipids, QTc	-	ROUTINE	ROUTINE	-
Aripiprazole	PO	Psychosis; irritability; weight-neutral	2 mg :: PO :: daily :: Start 2-5 mg daily; titrate by 5 mg q1wk; max 30 mg/day	None significant	Akathisia, EPS	-	ROUTINE	ROUTINE	-
Lamotrigine	PO	Mood stabilization; irritability	25 mg :: PO :: daily :: Start 25 mg daily x 2wk; then 50 mg daily x 2wk; titrate by 50 mg q2wk; max 400 mg/day	History of severe rash with lamotrigine	Rash (SJS risk); slow titration mandatory	-	ROUTINE	ROUTINE	-
Valproic acid	PO	Irritability; aggression; mood stabilization	250 mg :: PO :: BID :: Start 250 mg BID; titrate to level 50-100 mcg/mL	Hepatic disease; pregnancy (teratogenic); mitochondrial disease	LFTs, ammonia, level, weight	-	ROUTINE	ROUTINE	-
Carbamazepine	PO	Irritability; aggression; alternative mood stabilizer	100 mg :: PO :: BID :: Start 100 mg BID; titrate by 200 mg/wk; target level 4-12 mcg/mL	AV block; blood dyscrasias; concurrent MAOIs	CBC, LFTs, level, HLA-B*1502 in Asians	-	ROUTINE	ROUTINE	-
Buspirone	PO	Anxiety without sedation; adjunct for irritability	5 mg :: PO :: TID :: Start 5 mg TID; titrate by 5 mg q2-3d; max 60 mg/day	Concurrent MAOIs	None significant	-	ROUTINE	ROUTINE	-

3D. Symptomatic Treatments - Cognitive and Other¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Donepezil	PO	Cognitive impairment; limited evidence in HD	5 mg :: PO :: qHS :: Start 5 mg qHS; may increase to 10 mg after 4-6 weeks	GI bleeding; sick sinus syndrome	Nausea, bradycardia, diarrhea	-	ROUTINE	ROUTINE	-
Rivastigmine	PO/Patch	Cognitive impairment; alternative to donepezil	1.5 mg :: PO/Patch :: BID :: Start 1.5 mg BID or 4.6 mg patch; titrate monthly	Severe hepatic impairment	Nausea, weight loss	-	ROUTINE	ROUTINE	-
Memantine	PO	Moderate-severe cognitive impairment; neuroprotective theory	5 mg :: PO :: daily :: Start 5 mg daily; titrate by 5 mg/wk; target 10 mg BID	Severe renal impairment (dose adjust)	Confusion, constipation	-	ROUTINE	ROUTINE	-
Modafinil	PO	Apathy; excessive daytime sleepiness	100 mg :: PO :: AM :: Start 100 mg each morning; may increase to 200 mg; avoid afternoon dosing	Arrhythmias; severe anxiety	Insomnia, anxiety, BP	-	ROUTINE	ROUTINE	-
Methylphenidate	PO	Apathy; bradyphrenia; fatigue	5 mg :: PO :: BID :: Start 5 mg at breakfast and lunch; titrate by 5-10 mg q1wk; max 60 mg/day	Severe anxiety; psychosis; cardiac arrhythmia	HR, BP, appetite, insomnia	-	ROUTINE	ROUTINE	-
Trazodone	PO	Insomnia; irritability; mild sedation	25 mg :: PO :: qHS :: Start 25-50 mg qHS; titrate by 25-50 mg; max 200 mg for sleep	Concurrent MAOIs; priapism history	Orthostatic hypotension, priapism	-	ROUTINE	ROUTINE	-
Melatonin	PO	Insomnia; circadian rhythm disturbance	3 mg :: PO :: qHS :: Start 3 mg 30 min before bed; may increase to 9 mg	None	Generally well-tolerated	-	ROUTINE	ROUTINE	-
Botulinum toxin (onabotulinumtoxinA)	IM	Focal dystonia; bruxism; sialorrhea	Variable per muscle :: IM :: q12wk :: Dose depends on target muscles; repeat q12 weeks	Infection at site; myasthenia gravis	Weakness, dysphagia	-	-	ROUTINE	-
Glycopyrrolate	PO	Sialorrhea (drooling)	1 mg :: PO :: BID :: Start 1 mg BID; titrate to effect; max 2 mg TID	Glaucoma; urinary retention; GI obstruction	Dry mouth, constipation, urinary retention	-	ROUTINE	ROUTINE	-
Polyethylene glycol (MiraLAX)	PO	Constipation (common with reduced mobility and anticholinergics)	17 g :: PO :: daily :: 17 g in 8 oz liquid daily; may increase to BID	Bowel obstruction	Diarrhea if excessive	-	ROUTINE	ROUTINE	-
High-calorie nutritional supplements	PO	Weight loss; increased metabolic demands	1 can :: PO :: daily :: 1-3 cans (Ensure Plus, Boost Plus) daily between meals	None	Weight, nutritional markers	-	ROUTINE	ROUTINE	-

4. OTHER RECOMMENDATIONS¶

4A. Referrals & Consults¶

Recommendation	ED	HOSP	OPD	ICU
Huntington Disease Society of America (HDSA) Center of Excellence for comprehensive multidisciplinary care	-	ROUTINE	ROUTINE	-
Genetic counselor for pre-test counseling, results disclosure, and family testing discussion	-	ROUTINE	ROUTINE	-
Psychiatry for depression, suicidality assessment, irritability, and psychosis management	URGENT	ROUTINE	ROUTINE	-
Neuropsychology for baseline and serial cognitive assessment to guide care planning	-	-	ROUTINE	-
Speech-language pathology for swallowing evaluation and communication strategies	-	ROUTINE	ROUTINE	-
Physical therapy for gait training, fall prevention, and adaptive exercise program	-	ROUTINE	ROUTINE	-
Occupational therapy for ADL adaptation, home safety evaluation, and energy conservation	-	ROUTINE	ROUTINE	-
Dietitian/nutritionist for weight maintenance strategies and caloric supplementation	-	ROUTINE	ROUTINE	-
Social work for caregiver support, disability planning, and community resources	-	ROUTINE	ROUTINE	-
Palliative care for symptom management, advance care planning, and goals of care discussions	-	ROUTINE	ROUTINE	-
Pulmonology for respiratory assessment in advanced disease and ventilation decisions	-	ROUTINE	ROUTINE	-
Gastroenterology for PEG tube placement consideration in advanced dysphagia	-	ROUTINE	ROUTINE	-

4B. Patient Instructions¶

Recommendation	ED	HOSP	OPD
CRITICAL: Report suicidal thoughts immediately as depression is common and treatable in HD	STAT	STAT	ROUTINE
Do not drive if experiencing significant chorea, cognitive impairment, or sedating medication effects	URGENT	ROUTINE	ROUTINE
Maintain high caloric intake (3000-4000 kcal/day may be needed) due to hypermetabolic state	-	ROUTINE	ROUTINE
Eat slowly, take small bites, and remain upright 30 minutes after meals to reduce aspiration risk	-	ROUTINE	ROUTINE
Complete advance directive and healthcare power of attorney while capacity is preserved	-	ROUTINE	ROUTINE
Inform all healthcare providers about HD as many common medications can worsen symptoms	-	ROUTINE	ROUTINE
First-degree relatives have 50% risk; genetic counseling available but genetic testing is a personal choice	-	ROUTINE	ROUTINE
Avoid alcohol which worsens balance, cognition, and interacts with medications	-	ROUTINE	ROUTINE

4C. Lifestyle & Prevention¶

Recommendation	ED	HOSP	OPD
Regular aerobic exercise (walking, swimming, stationary bike) improves motor function and mood	-	ROUTINE	ROUTINE
Fall prevention: remove home hazards, adequate lighting, grab bars, non-slip surfaces	-	ROUTINE	ROUTINE
Maintain social engagement and meaningful activities to reduce depression and apathy	-	ROUTINE	ROUTINE
Cognitive engagement through puzzles, reading, and structured activities may help maintain function	-	ROUTINE	ROUTINE
Structure daily routine with consistent timing for medications, meals, and activities	-	ROUTINE	ROUTINE
Caregiver respite and support groups essential to prevent caregiver burnout	-	ROUTINE	ROUTINE
Smoking cessation to reduce aspiration pneumonia risk and cardiovascular disease	-	ROUTINE	ROUTINE
Limit caffeine if insomnia or anxiety are problematic	-	ROUTINE	ROUTINE

SECTION B: REFERENCE¶

5. DIFFERENTIAL DIAGNOSIS¶

Alternative Diagnosis	Key Distinguishing Features	Tests to Differentiate
Huntington disease-like 1 (HDL1)	Prion protein gene mutation; similar phenotype	PRNP gene testing
Huntington disease-like 2 (HDL2)	African ancestry; JPH3 gene mutation	JPH3 gene testing
Spinocerebellar ataxia 17 (HDL4)	Prominent ataxia; TBP gene expansion	TBP gene testing
Chorea-acanthocytosis	Orolingual dystonia; self-mutilation; acanthocytes	Peripheral smear; VPS13A gene testing
McLeod syndrome	X-linked; cardiomyopathy; elevated CK	Kell antigen typing; XK gene testing
Sydenham chorea	Post-streptococcal; younger patients; self-limited	ASO titer; anti-DNAse B
Benign hereditary chorea	Childhood onset; non-progressive; NKX2-1 mutation	NKX2-1 gene testing; family history
Wilson's disease	Younger onset; Kayser-Fleischer rings; hepatic disease	Ceruloplasmin; 24-hr urine copper; slit lamp
Neuroacanthocytosis	Peripheral neuropathy; seizures; elevated CK	Peripheral smear; genetic testing
Tardive dyskinesia	Antipsychotic exposure; orobuccal predominant	Medication history; AIMS scale
Anti-NMDA receptor encephalitis	Psychiatric symptoms; seizures; dyskinesias	NMDA receptor antibodies; CSF analysis

6. MONITORING PARAMETERS¶

Parameter	Frequency	Target/Threshold	Action if Abnormal	ED	HOSP	OPD	ICU
UHDRS (Unified Huntington's Disease Rating Scale)	Every 6-12 months	Document trend; track motor progression	Adjust medications; update care plan	-	-	ROUTINE	-
Depression screening (PHQ-9)	Every visit; monthly if on VMAT2 inhibitor	PHQ-9 <5	Intensify antidepressant; psychiatry referral if PHQ-9 >15	URGENT	ROUTINE	ROUTINE	-
Suicidality assessment	Every visit	No active suicidal ideation	Immediate psychiatric evaluation; safety planning	STAT	STAT	ROUTINE	-
Cognitive assessment (MoCA or MMSE)	Every 6-12 months	Document trend	Update care planning; capacity assessment	-	-	ROUTINE	-
Weight	Every visit	Stable or increasing	Increase caloric intake; dietitian referral	-	ROUTINE	ROUTINE	-
Swallowing function	Annually or if symptoms	No aspiration	Modify diet texture; speech therapy; PEG consideration	-	ROUTINE	ROUTINE	-
ECG (if on VMAT2 inhibitor)	Baseline and with dose changes	QTc <500 ms	Hold medication if QTc >500 ms; reduce dose	-	ROUTINE	ROUTINE	-
Functional independence (TFC)	Every 6-12 months	Document functional stage	Adjust level of care; advance care planning	-	-	ROUTINE	-
Caregiver burden assessment	Annually	Sustainable caregiving	Respite care; support resources	-	ROUTINE	ROUTINE	-
Falls frequency	Each visit	Zero falls	PT referral; home safety; medication review	-	ROUTINE	ROUTINE	-

7. DISPOSITION CRITERIA¶

Disposition	Criteria
Discharge home	Stable psychiatric status; adequate oral intake; safe swallowing; caregiver available; outpatient follow-up arranged
Admit to floor	Severe psychiatric symptoms requiring stabilization; aspiration pneumonia; significant weight loss requiring evaluation; severe chorea causing exhaustion or injury
Admit to ICU	Aspiration with respiratory failure; severe rhabdomyolysis from chorea; neuroleptic malignant syndrome; suicidal attempt requiring medical stabilization
Skilled nursing facility	Advanced disease; 24-hour care needs; dysphagia requiring supervision; frequent falls; caregiver unable to provide required care
Hospice referral	End-stage disease (TFC stage 5); recurrent aspiration; patient/family goals favor comfort care

8. EVIDENCE & REFERENCES¶

Recommendation	Evidence Level	Source
Tetrabenazine reduces chorea in HD	Class I, Level A	Huntington Study Group. Neurology 2006
Deutetrabenazine reduces chorea with improved tolerability	Class I, Level A	Huntington Study Group. JAMA 2016
CAG repeat length inversely correlates with age of onset	Class II, Level B	Andrew et al. Nat Genet 1993
AAN practice parameter for HD treatment	Guideline	Armstrong & Miyasaki. Neurology 2012
High suicide rate in HD requires screening	Class II, Level B	Paulsen et al. J Neuropsychiatry Clin Neurosci 2005
UHDRS reliable for tracking disease progression	Class II, Level A	Huntington Study Group. Mov Disord 1996
CYP2D6 genotype affects tetrabenazine metabolism	Class II, Level B	Xenazine FDA prescribing information 2008
Genetic counseling improves outcomes in at-risk individuals	Class II, Level B	Tibben. Handb Clin Neurol 2007
Dysphagia common and associated with aspiration risk	Class II, Level C	Heemskerk & Roos. Dysphagia 2011
Multidisciplinary care improves outcomes	Class III, Level C	Veenhuizen & Bherer. J Huntingtons Dis 2017
Exercise benefits motor and cognitive function	Class II, Level B	Quinn et al. Cochrane Database Syst Rev 2022
Valbenazine effective for hyperkinetic movements	Class I, Level A	Hauser et al. JAMA Neurol 2017

CHANGE LOG¶

v1.1 (January 30, 2026) - Reformatted lab tables (1A/1B/1C) to standard column order: Test | ED | HOSP | OPD | ICU | Rationale | Target Finding - Reformatted imaging tables (2A/2B/2C) to standard column order: Study | ED | HOSP | OPD | ICU | Timing | Target Finding | Contraindications - Added inline CPT codes to all lab tests and imaging studies - Fixed structured dosing format: starting dose only in first field across all treatment sections - Expanded cross-references ("Same as tetrabenazine", "Same as citalopram") with actual content - Added clinical synonyms for searchability - Expanded ICD-10 codes (added F02.80, F02.81) - Added VERSION/CREATED/REVISED header block

v1.0 (January 27, 2026) - Initial template creation - Comprehensive coverage of chorea management with VMAT2 inhibitors - Psychiatric symptom management with multiple drug classes - Genetic testing and counseling guidance - Dysphagia and nutritional support - End-of-life and palliative care considerations - Structured dosing format for order sentence generation

APPENDIX A: Huntington's Disease Staging¶

Stage	TFC Score	Functional Status	Care Needs
Stage 1 (Early)	11-13	Engaged in occupation; handles finances; performs all ADLs	Independent; outpatient monitoring
Stage 2 (Early-Intermediate)	7-10	Reduced work capacity; handles daily affairs with minimal assistance	Minimal assistance; may need supervision for complex tasks
Stage 3 (Intermediate)	3-6	Unable to work; requires help with finances; still manages basic ADLs	Moderate assistance; partial supervision
Stage 4 (Late-Intermediate)	1-2	Requires assistance with most ADLs; can live at home with care	Substantial assistance; may need skilled care
Stage 5 (Advanced)	0	Total dependence; requires full care	Total care; nursing facility or hospice

APPENDIX B: Genetic Counseling Considerations¶

Pre-Test Counseling Essentials¶

Implications of positive result: Progressive, fatal disease with no cure; 50% risk to offspring
Implications of negative result: No increased risk, but survivor guilt possible
Intermediate alleles (27-35 repeats): Not affected, but may expand in offspring
Reduced penetrance (36-39 repeats): May or may not develop HD; difficult counseling
Full penetrance (40+ repeats): Will develop HD if lives long enough
Insurance and discrimination: GINA protects health insurance and employment; does NOT cover life, disability, or long-term care insurance
Timeline: Results typically 2-4 weeks; follow-up support essential

Testing of At-Risk Individuals¶

Minimum age 18 for predictive testing (legal adult)
Do not test minors unless symptomatic
Recommended: 2+ counseling sessions before testing
Wait period between disclosure and decision
Support system should be in place before results

Prenatal Testing Options¶

Prenatal diagnosis: CVS at 10-12 weeks or amniocentesis at 15-20 weeks
Preimplantation genetic testing (PGT): IVF with embryo selection
Non-disclosure testing: Pregnancy terminated if affected without revealing parent's status
Exclusion testing: Determines if fetus inherited grandparent's chromosome without revealing parent's status

APPENDIX C: End-of-Life Planning¶

Advance Directive Considerations Specific to HD¶

Issue	Considerations
Feeding tubes	PEG may prolong survival but not necessarily quality of life; discuss before capacity lost
Mechanical ventilation	Usually not consistent with comfort goals in end-stage HD
Antibiotic use	Consider limiting to comfort measures in advanced disease
Hospitalization	May prefer comfort care at home or hospice facility
Autopsy/brain donation	Important for research; discuss while patient can consent

Hospice Eligibility Criteria (General Guidance)¶

TFC Stage 5 (Total Functional Capacity score 0)
Unable to ambulate without substantial assistance
Unable to communicate intelligibly
Recurrent aspiration pneumonia
PPS (Palliative Performance Scale) ≤50%
Significant weight loss despite nutritional support