Dropped head syndrome in severe intractable epilepsies with mental retardation

Abstract

Dropped head syndrome is characterized by a gradual forward sagging of the head due to the isolated weakness of the neck extensor muscles. The syndrome has a relatively benign clinical course. To date, there have been no reports of dropped head syndrome in epileptic patients. Nine patients with intractable epilepsy (mean age, 33.6+/-9.91 years), each presenting with apparent dropped head, were evaluated. The duration of the drooping head symptom varied from 3 to 15 years (mean, 7.4+/-4.06 years), with a slowly progressing weakness in most of the patients. In all of the patients, extensive clinical, laboratory, electrophysiological, histopathological, and neuroimaging examinations were performed. The weakness in all of the subjects was strictly limited to the cervical paraspinal muscles. Laboratory studies produced normal results from all subjects. EMG and muscle biopsy were normal or revealed subtle nonspecific myopathic changes without inflammation in the cervical paraspinal muscles. Polymyographic investigation revealed that none of the patients had convincing dystonic spasms of the anterior neck muscles. No atrophy or fatty changes of the neck extensor muscles were observed on CT or MRI. In most of the patients (7/9), altered L-carnitine concentrations were observed (four patients displayed a marked decrease in plasma carnitine concentrations, and three other patients showed abnormalities in urinary excretion of carnitine). These findings seem to suggest that a secondary carnitine deficiency, induced by antiepileptic drugs (principally valproic acid), represents a plausible pathogenetic mechanism for the development of dropped head in some epileptic patients.