Hereditary spastic paraplegias (HSP) are a rare group of inherited neurodegenerative diseases which mainly affect the longest axons of the corticospinal tract and the dorsal column (which supply the lower limbs). HSP is caused by defects in genes which code for proteins essential for fast axonal neurotransmission. HSP can affect any age group. Patients present with upper motor neuron palsy of bilateral lower limbs, gait abnormalities, and urinary urgency/urge incontinence. Dorsal column dysfunction is usually mild. Additional neurological features such as epilepsy, peripheral neuropathy, or cerebellar signs may be present (complicated HSP). Diagnosis is mainly clinical. MRI of the spinal cord may demonstrate spinal cord atrophy. Treatment is mainly supportive, with skeletal muscle relaxants, botulinum toxin, and physiotherapy for muscle spasticity. HSP may be nonprogressive (childhood-onset) or progressive (adult-onset). Patients with progressive HSP are often wheelchair-bound by the age of 70 years. Patients with HSP have a normal life-expectancy.
The diagnosis of HSP is based on a positive family history, characteristic clinical features, and the exclusion of other neurological conditions (see differential diagnosis below).
Vitamin B12 levels should be checked; HIV and syphilis testing should also be performed to rule out these conditions.
Lumbar puncture and CSF analysis are usually normal!
There is no known cure for HSP.
Surgery may be required to release contractures.
Genetic counseling should be offered to patients with a child with HSP or to an adult with adult-onset HSP.
Prognosis depends on the age of onset.
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