Huntington disease

Background

Huntington disease (HD) is a progressive, autosomal dominant neurodegenerative disorder caused by CAG trinucleotide repeat expansion in the HTT gene on chromosome 4. Onset typically occurs between ages 30 and 50. HD is characterized by a triad of movement abnormalities, psychiatric symptoms, and cognitive decline. While not usually a diagnosis made in the ED, patients with known HD often present with behavioral disturbances, injuries from falls, or complications related to disease progression.

Clinical Features

Motor symptoms

• Chorea (involuntary, jerky movements)
• Clumsiness, unsteady gait
• Dystonia or rigidity (in later stages)

Cognitive decline

• Poor executive function, memory deficits
• Progressive dementia

Psychiatric/behavioral symptoms

• Depression, apathy, anxiety
• Psychosis, irritability, impulsivity
• Suicide risk is elevated

Other

Dysphagia, weight loss, incontinence in later stages

Differential Diagnosis

• Wilson disease (especially in younger patients)
• Drug-induced (e.g., levodopa, antipsychotics)
• Sydenham chorea (post-streptococcal)
• Lupus or other autoimmune encephalopathies
• Hyperthyroidism
• Neuroacanthocytosis, spinocerebellar ataxias

Evaluation

Workup

• Vitals + glucose
• Electrolytes, BUN/Cr, LFTs
• Toxicology screen (especially if altered)
• TSH if new movement disorder
• Head CT or MRI if new-onset neurologic symptoms or trauma
• Consider psychiatric evaluation if behavioral disturbance, suicidality, or psychosis

Diagnosis

• Definitive diagnosis is genetic testing for >36 CAG repeats in the HTT gene
• Brain imaging may show caudate nucleus atrophy, but is not diagnostic
• In ED, diagnosis is often known or suspected from history/family

Management

• Chorea: May be treated with tetrabenazine, deutetrabenazine, or antipsychotics (e.g., risperidone)
• Psychosis/agitation: Use atypical antipsychotics (e.g., quetiapine, olanzapine) with caution
• Depression/suicidality: SSRIs are first-line; ED physicians should screen all HD patients for suicide risk
• Injury/fall management: Evaluate for trauma (head, cervical spine, fractures)
• Aspiration or dysphagia complications: May require speech/swallow evaluation or acute airway management

Disposition

Admission:

• Acute injury, trauma, or fall
• Aspiration pneumonia or dysphagia-related complications
• Severe psychiatric symptoms (e.g., suicidality, psychosis)

Necessary for Discharge:

• Follow-up with neurology or movement disorder specialist
• Clear communication with caregivers
• Psychiatric or social work consult if needed for resources/care planning

External Links

GeneReviews: Huntington Disease