Human Lice

can be affected when there is cervical or lumbar involvement,^ There is an inverse relationship between dermatomal and myotomal involvement. Eifty percent of all dermatomal lesions are in the thoracic area, but less than three percent of the myotomal paresis is in the thoracic segments. Obversely, 50% of zoster paresis is in the cranial nerves, but only 15% of the skin lesions. The prognosis is related to the severity of the damage and the location. The closer the lesion is to the spinal cord or brain, the less chance there is of complete regeneration. Over half the patients afflicted with zoster paresis recover completely, and another 30% have at least partial recovery,"* As a rule, only one ganglion is markedly involved in herpes zoster. Usually, a lymphocytic infiltration and degeneration occur not only in the ganglion, but in the adjacent nerve as well. Less severe damage can also occur to the immediately adjacent ganglia,^ Most dermatomes and myotomes are supplied by three or four dorsal or ventral roots. Hence, injury from herpes to a single root usually results in either hypoesthesia or weakening of the effected area or muscle, A complete loss of sensation or motor supply will occur only if several spinal ganglia are involved or if a cranial nerve with unique function is involved, such as occurs in the Ramsay Hunt syndrome. Because of this overlap of innervation, and because most paralysis occurs within the first several weeks of disease, it is unlikely that many abdominal or intercostal muscle paralyses would be discovered by a clinician or patient more concerned with an acutely painful eruption with swelling. Only those cases which occur late and acutely in the course of thoracic zoster would probably be noted.