William W. Campbell

Focal atrophy of the multifidus muscle in lumbosacral radiculopathy

A patient with compelling clinical and electrodiagnostic evidence of a right L5 radiculopathy had focal atrophy of the multifidus at the appropriate level, which served to confirm the radicular nature of the process. The multifidus muscles are innervated by a single root, in contrast to the polysegmental innervation of the rest of the paraspinal muscle mass. Imaging studies may complement needle electromyography in the evaluation of this important structure.

Anterior Horn Changes of Motor Neuron Disease Associated with Demyelinating Radiculopathy

Morphologic study of the spinal cord of a patient with generalized motor deficits revealed changes in the anterior horns characterized by the selective loss of large motor neurons, gliosis and the abnormal accumulation of 10 nm filaments which appeared as argyrophilic spheroids in the perikarya and axons of motor neurons. The ventral roots were predominantly affected and showed a variable loss of axons. The remaining axons displayed prominent onion-bulb formations, frequent axonal sprouting and occasionally evidence of active demyelination. The coexistence of a demyelinating motor radiculopathy and anterior horn changes simulating those of amyotrophic lateral sclerosis (ALS) may contribute to our understanding of the unresolved question of whether the neuronal perikaryon or its axon is the primary target in the pathogenesis of ALS. These observations also indicate that a rigid separation of pathogenetic mechanisms into neuronopathy, axonopathy and myelinopathy may not be always possible.