Neurology · MU Sofia

70. Spinocerebellar degenerations and ataxias

Covers progressive degenerative disorders of the cerebellum, spinal cord and their connections, classified into hereditary forms such as spinocerebellar ataxias and Friedreich ataxia, and acquired causes including alcohol, stroke, tumours and vitamin deficiencies. It then describes the cerebellar syndrome, specific types, examination tests such as finger-to-nose and Romberg, diagnostic imaging and genetic testing, differential diagnosis from sensory, vestibular, demyelinating and vascular causes, and treatment.

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Topic 70 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 346 words (2 min of reading), with 16 flashcards.

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  1. Spinocerebellar degenerations and ataxias

Spinocerebellar degenerations and ataxias

Definition: Spinocerebellar degenerations and ataxias are a group of progressive neurodegenerative disorders affecting the cerebellum, spinal cord, and their connections, leading to ataxia (loss of coordination).

  • They may be hereditary (most common in spinocerebellar ataxias) or acquired.

Classification

  1. A. Hereditary Ataxias (Spinocerebellar Ataxias – SCA): Autosomal dominant (most SCAs). Autosomal recessive (e.g., Friedreich ataxia)
  2. B. Acquired Ataxias: Alcoholic cerebellar degeneration. Multiple sclerosis. Tumors (posterior fossa). Stroke (cerebellar infarction). Vitamin deficiencies (B1, B12, E). Toxic (drugs, alcohol)

Pathogenesis

Damage to: Cerebellar cortex. Spinocerebellar tracts. Posterior columns

➡️ Leads to disruption of coordination of movement, posture, and balance.

Clinical Features (Cerebellar Syndrome)

  1. A. Gait and Trunk Ataxia: Wide-based gait. Unsteady walking. Difficulty standing upright
  2. B. Limb Ataxia: Intention tremor. Dysmetria (past-pointing). Dysdiadochokinesia (impaired rapid alternating movements)
  3. C. Speech Disturbance: Scanning (staccato) speech. Slurred articulation
  4. D. Eye Movement Disorders: Nystagmus. Gaze-evoked oscillations
  5. E. Hypotonia: Decreased muscle tone. Pendular reflexes

Specific Types

  1. A. Friedreich Ataxia (Autosomal Recessive)

Pathology

  • Degeneration of: Spinocerebellar tracts. Posterior columns. Corticospinal tracts

Clinical Features: Onset in childhood/adolescence. Progressive ataxia. Loss of vibration and position sense. Weakness. Absent reflexes (early), later spasticity. Cardiomyopathy (important systemic feature)

Key Sign: Sensory + cerebellar ataxia

  1. B. Spinocerebellar Ataxias (SCA types)

Features: Autosomal dominant. Adult onset. Progressive cerebellar ataxia. Variable pyramidal and extrapyramidal signs

  1. C. Alcoholic Cerebellar Degeneration: Mainly affects anterior superior cerebellar vermis. Gait ataxia predominant. Lower limb coordination affected more than upper limbs

Examination

Cerebellar Tests

  • Finger-to-nose test → dysmetria
  • Heel-to-shin test → ataxia
  • Rapid alternating movements → dysdiadochokinesia
  • Romberg test → usually negative (pure cerebellar lesion)

Diagnosis

  • Clinical Diagnosis: Based on cerebellar signs + progression pattern
  • MRI Brain: Cerebellar atrophy. Vermis degeneration (alcoholic type). Brainstem atrophy in hereditary forms
  • Genetic Testing: For spinocerebellar ataxias (SCA types)

Differential Diagnosis

  1. 1. Sensory Ataxia: Positive Romberg sign. Loss of vibration sense
  2. 2. Vestibular Ataxia: Vertigo. Nystagmus. Falls to one side
  3. 3. Multiple Sclerosis: Multifocal CNS signs
  4. 4. Stroke: Sudden onset cerebellar signs

Treatment

  • General: No curative therapy for most hereditary forms
  • Symptomatic: Physiotherapy. Occupational therapy. Speech therapy.
  • Treat Underlying Causes: Alcohol cessation. Vitamin replacement (B1, B12, E). Tumor removal if present

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