[Electro-clinical data in medullary forms of the Chiari malformation without syringomyelia]

The electrophysiological findings in 18 patients with Arnold-Chiari malformation (ACM) revealed by spinal symptoms excluding syringomyelic syndrome (Brown-Sequard syndrome, paraparesis with or without posterior column involvement, motor neuron syndrome or more complex myelopathies) are reported. In 16 cases, EMG disclosed abnormalities consistent with lesion of anterior horn cells restricted to upper limb in 7 cases, and generalized in 9 cases. In 2 cases, motor and sensory conductions were abnormal. The occurrence of such abnormalities in patients with ACM is emphasized as they could lead to confusion with amyotrophic lateral sclerosis or spinal muscular atrophy. Neuroradiological studies are therefore necessary owing to possible surgical treatment. The hypothesis relating lower motor involvement and ACM are reviewed.