[Segmental motor paralysis caused by the varicella zoster virus. Clinical study and functional prognosis]

Segmental motor paralysis of the limbs (SMP) complicates 2-3% of the cases of cutaneous herpes zoster. Viral invasion and inflammation of the motor neurons of the anterior horn cells by the varicella-zoster virus (VVZ) causes clinical weakness at the same time and site as the cutaneous eruption.

To analyze the clinical findings, complementary investigations and functional prognosis of patients with SMP at brachial plexus and lumbosacral levels.

We made a retrospective study of 10 patients with SMP admitted to the Hospital Universitario Gregorio Maranon de Madrid during 1989-1999, aged between 38 and 84 years (6 women, 4 men). Neurological examination was done, including muscle balance, complementary studies including microbiology (serum and CSF serology, viral PCR-ADN), neurophysiology using MNR of the spine and plexuses and functional prognosis on the NDS, NSS and RANKIN scales.

There is a close relationship between dermatome and myotome involvement (90%). The brachial and lumbosacral plexuses were equally affected (50%). Plasma and CSF VVZ serology was positive in 50% of the cases, permitting diagnosis of a patient with no cutaneous lesions (zoster sine herpete). Denervation of the myotomes involved and the paraspinal muscles was shown on neurophysiological studies. In most cases there was functional improvement, with complete functional recovery in 80% of the cases after 12 months.

VVZ should be considered amongst the aetiologies of SMP, even in the absence of cutaneous lesions (zoster sine herpete). The SMP coincides in time and place with the dermatome lesions. In most patients there is complete functional recovery within 12 months.