Nerve conduction studies in spastic paraplegia, optic atrophy, and neuropathy (SPOAN) syndrome

SPOAN (spastic paraplegia, optic atrophy, and neuropathy) syndrome is an autosomal recessive neurodegenerative disorder identified in a large consanguineous Brazilian family.

Twenty-seven patients with SPOAN syndrome (20 women), aged 4-58 years, underwent nerve conduction studies (NCS) of the median, ulnar, tibial, and fibular nerves, and sensory NCS of the median, ulnar, radial, sural, and superficial fibular nerves.

Sensory nerve action potentials were absent in the lower limbs and absent in >80% of upper limbs. Motor NCS had reduced amplitudes and borderline velocities in the upper limbs and absent compound muscle action potentials (CMAPs) in the lower limbs.

The neuropathy in SPOAN syndrome is a severe, early-onset sensory-motor axonal polyneuropathy. Normal NCS seem to rule-out this condition.