Dejerine–Sottas disease

Dejerine–Sottas disease, also known as Dejerine–Sottas syndrome, Dejerine–Sottas neuropathy, progressive hypertrophic interstitial polyneuropathy of childhood and onion bulb neuropathy (and, hereditary motor and sensory polyneuropathy type III and Charcot–Marie–Tooth disease type 3), is an autosomal dominant or autosomal recessive neuropathy, which causes damage to the peripheral nerves.

Eponym
It is named for Joseph Jules Dejerine and Jules Sottas.

Causes
Dejerine-Sottas Disease is caused by a genetic defect either in the proteins found in axons or the proteins found in myelin. It can be either an autosomal dominant or autosomal recessive neuropathy. Specifically, it has been associated with MPZ, PMP22, PRX, and EGR2.

Symptoms
Onset occurs in infancy or early childhood, usually before 3 years of age. Progression is slow until the teenage years at which point it may accelerate, resulting in severe disability.

Symptoms are usually more severe and rapidly progressive than in the other more common Charcot–Marie–Tooth diseases. Some carriers may never walk and solely use wheelchairs by the end of their first decade, while others may need only a cane (walking stick) or similar support through life.

Dejerine-Sottas Disease is characterized by moderate to severe lower and upper extremity weakness and loss of sensation, which occur mainly in the lower legs, forearms, feet and hands. Loss of muscle mass and reduced muscle tone can occur as the disease progresses. Other symptoms may include pain in the extremities, curvature of the spine, clawed hands, foot deformities, ataxia, peripheral areflexia, and slow acquisition of motor skills in childhood. Symptoms that are less common can include limitation of eye movements, other eye problems such as nystagmus or anisocoria, or mild hearing loss.

Diagnosis
On medical imaging, the nerves of the extremities (and cranial nerves in some cases) appear enlarged due to hypertrophy of the connective interstitial tissue, giving the nerves a distinct 'onion-bulb' appearance. Peripheral (and possibly cranial) nerve excitability and conduction speed are reduced.