[Isolated cervicothoracic spinal amyotrophy caused by hydromyelia. Stabilization by a ventricular shunt]

A 25-year-old man developed marked weakness of the upper limbs and shoulder girdle over a period of 6 months. On examination there was amyotrophy, fasciculations and areflexia of the upper limbs with increased lower limb reflexes. Sensation and CSF were normal. CT scan showed a thickened cord with a central medullary cavity of triangular shape with a ventral base. Myelobulbography showed a type I Arnold-Chiari malformation. Spinal angiography was normal. Isotopic studies showed early ventricular reflux. Although infusion tests gave negative results a ventriculoperitoneal shunt was performed and the condition stabilized. Follow-up examination 4 years later confirmed the absence of sensory disorders and nervous arthropathies. The mechanism of production of cervical cord lesions during hydromyelia may be related to hydrocephalus, with fluid absorption across the ependymal walls, or to venous stasis determined by the Arnold-Chiari malformation. The ventral extension of the central cord cavity accounted for the isolated atypical lesion of the anterior horns.