Huntington Disease, Spinocerebellar Ataxias, Motor Neuron Disease and Friedreich Ataxia
Connect the key pathological changes, neurological pathways, clinical patterns and management principles for rapid revision.
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1. THE TOPIC IN ONE CONNECTED FLOW
These disorders become easier to separate when the affected neural system is identified first. Selective degeneration of the basal ganglia, cerebellar pathways, motor neurons or combined cerebellar-sensory-pyramidal pathways produces a different functional disturbance and therefore a different clinical pattern. Management then follows the main disability produced by that pathway damage.
Inherited cerebellar degeneration
Sporadic/familial motor neuron degeneration
Frataxin deficiency
Cerebellar pathways
UMN / LMN / bulbar neurons
Sensory + pyramidal systems
Loss of coordination
Denervation / spasticity
Ataxia + sensory loss
Gait / limb ataxia
Progressive weakness
Childhood ataxia + pyramidal signs
Cerebellar syndrome
UMN ± LMN combination
Absent reflexes + extensor plantars
Rehabilitation
Disease modification in ALS
Cardiac / orthopedic follow-up in Friedreich ataxia
2. KEY CLINICAL CONNECTIONS
HTT CAG expansion
→ striatal neuronal loss
→ reduced suppression of unwanted movement
→ chorea.
Caudate atrophy
→ enlargement of adjacent lateral ventricles
→ characteristic morphological clue.
Anterior horn-cell loss
→ denervation
→ wasting and fasciculations.
Corticospinal degeneration
→ hyperreflexia and spasticity
→ mixed UMN–LMN pattern in ALS.
Cerebellar pathway dysfunction
→ dysmetria, gait ataxia and dysarthria
→ cerebellar syndrome.
Friedreich ataxia adds sensory and corticospinal involvement
→ proprioceptive loss + extensor plantars.