Neurology · MU Sofia

73. Hereditary spastic paraparesis

Covers hereditary spastic paraparesis as a group of genetic neurodegenerative disorders causing progressive spastic weakness of the legs through corticospinal tract degeneration. It sets out the inheritance patterns, the pure and complicated classification, clinical features and examination findings, diagnostic tests, differential diagnoses such as multiple sclerosis and vitamin B12 deficiency, symptomatic treatment, and prognosis. A labelled picture accompanies the clinical features section.

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

Topic 73 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 305 words (2 min of reading), with 16 flashcards.

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  1. Hereditary spastic paraparesis

Hereditary spastic paraparesis

Definition: Hereditary spastic paraparesis (HSP) is a group of genetic neurodegenerative disorders characterized primarily by progressive spastic weakness of the lower limbs due to degeneration of the corticospinal tracts (upper motor neurons).

Etiology & Genetics

  • Most commonly autosomal dominant
  • Also autosomal recessive and X-linked forms
  • Main genetic involvement: Mutations affecting axonal transport and long descending motor pathways. “Length-dependent axonopathy” (longest fibers affected first)

Pathogenesis

  • Degeneration of corticospinal tracts (UMN fibers)
  • Sometimes posterior columns also involved (in complicated forms)
  • Leads to: Spasticity. Weakness. Hyperreflexia (especially in legs)

Classification

  1. A. Pure (Uncomplicated) HSP: Only pyramidal signs. Slowly progressive spastic paraparesis
  2. B. Complicated HSP

Spastic paraparesis + additional neurological signs: Ataxia. Epilepsy. Peripheral neuropathy. Cognitive impairment. Optic atrophy

Clinical Features

Motor Symptoms: Progressive spasticity of lower limbs. Weakness (legs > arms). Difficulty walking. Stiff gait

Reflexes: Hyperreflexia (especially legs). Clonus. Positive Babinski sign

Gait: Spastic gait (“scissoring gait”). Dragging feet

Sensory System: Usually normal in pure form. May be impaired in complicated forms (posterior column involvement)

Examination Findings

  • Increased muscle tone (spasticity)
  • Hyperactive deep tendon reflexes
  • Extensor plantar response (Babinski)
  • Weakness predominantly in lower limbs
  • Normal or mildly affected upper limbs

Diagnosis

  • Clinical Diagnosis (key): Slowly progressive bilateral spastic paraparesis
  • MRI: Usually normal in pure HSP. May show spinal cord thinning or mild degeneration
  • Genetic Testing: Confirms subtype (SPA/STX gene mutations etc.)
  • Electrophysiology: Usually normal in pure HSP. Helps exclude peripheral neuropathy

Differential Diagnosis

  1. 1. Multiple Sclerosis: Relapsing-remitting course. CNS lesions on MRI
  2. 2. Spinal Cord Compression: Sensory level present. Pain often present
  3. 3. Primary Lateral Sclerosis: UMN disease (no hereditary pattern)
  4. 4. Vitamin B12 Deficiency: Posterior column involvement. Sensory ataxia

Treatment

  • No curative therapy
  • Symptomatic Management: Baclofen (spasticity). Tizanidine. Physiotherapy. Orthotic support. Walking aids

Complicated Cases

  • Treat associated symptoms: Antiepileptics (if seizures). Neurorehabilitation

Prognosis: Slowly progressive lifelong disorder

  • Pure forms: relatively benign progression
  • Complicated forms: more disabling

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