Neurology · MU Sofia

69. Huntington's chorea, dystonias, tics

Covers Huntington's disease as an autosomal dominant condition with a CAG repeat expansion, its striatal pathogenesis, and its motor, cognitive and psychiatric features, including MRI findings and treatment. Then describes dystonias, with a primary and secondary classification and a body-area classification of focal, segmental, multifocal and generalised forms, plus treatment options. Ends with tics, their motor and vocal types, Tourette syndrome, and behavioural and drug treatments.

Inside: 1 section · 1 labelled picture · 16 flashcards · 2 min

Topic 69 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 331 words (2 min of reading), with 16 flashcards.

In this note

  1. Huntingtons chorea, dystonias, tics

Huntingtons chorea, dystonias, tics

1. Huntington’s Chorea

Definition: Huntington Disease is a progressive autosomal dominant neurodegenerative disease characterized by:

  • Chorea. Psychiatric symptoms. Cognitive decline (dementia)

Etiology & Genetics

  • Autosomal dominant inheritance
  • CAG trinucleotide repeat expansion (HTT gene)
  • Anticipation (earlier onset in successive generations)

Pathogenesis

  • Degeneration of caudate nucleus and putamen (striatum)
  • ↓ GABAergic neurons
  • Loss of inhibitory control → hyperkinetic movements (chorea)

Clinical Features

1. Motor Symptoms: Chorea (jerky, dance-like movements). Dystonia (later). Abnormal gait. Motor impersistence (cannot maintain grip)

2. Cognitive Symptoms: Progressive dementia. Executive dysfunction. Memory impairment

3. Psychiatric Symptoms: Depression. Irritability. Psychosis. Personality changes

Examination: Choreiform movements. Grimacing. Tongue protrusion. Difficulty maintaining voluntary posture

Diagnosis

  • Genetic testing (CAG repeats)
  • MRI: Caudate nucleus atrophy (“box-like ventricles”)

Treatment (No cure)

Symptomatic: Tetrabenazine (reduces chorea). Antipsychotics for psychiatric symptoms

2. Dystonias

Definition: Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal postures or repetitive movements.

Types

By etiology

A. Primary Dystonia: Genetic. No structural brain lesion

Types by body area affected:

  • 1) Focal: affects one specific part of the body (blepharospasm)
  • 2) Segmental: affects two or more adjacent parts (oromandibular dystonia)
  • 3) Multifocal: affects two or more non-connected parts
  • 4) Generalized: affects most or all of the body

B. Secondary Dystonia: Stroke. Drugs (antipsychotics → tardive dystonia). Wilson disease. Brain injury

Clinical Features: Twisting movements. Abnormal postures. Neck (torticollis). Hand (writer’s cramp). Face (blepharospasm)

Characteristics: May be task-specific (e.g., writing). Worsens with voluntary movement. Improves with rest or sensory tricks (geste antagoniste)

Treatment: Botulinum toxin (focal dystonia). Anticholinergics. Baclofen. Deep brain stimulation (severe cases)

3. Tics

Definition: Tics are sudden, rapid, recurrent, non-rhythmic movements or vocalizations.

Types

A. Motor Tics: Eye blinking. Facial grimacing. Shoulder shrugging

B. Vocal Tics: Throat clearing. Grunting. Sniffing. Coprolalia (rare)

Tourette Syndrome: Multiple motor tics + ≥1 vocal tic. Onset in childhood. Chronic course

Pathogenesis

  • Dysfunction of cortico-striato-thalamo-cortical circuits
  • Dopaminergic overactivity

Clinical Features: Suppressible (temporary). Premonitory urge before tic. Worsens with stress. Improves during sleep

Treatment

  • Behavioral therapy
  • Dopamine blockers: Haloperidol. Risperidone
  • Alpha-2 agonists: Clonidine

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