Zoster encephalitis Many of the writings on zoster encephalitis give the impression of a severe illness that occurs temporally remote from the attack of shingles in an immunosuppressed patient. Indeed, such instances have been reported in patients with HIV and may be concurrent with the small vessel vasculitis described below. However, our experience is more in keeping with that of Jemsek and colleagues and of Peterslund, who described a less severe form of encephalitis in patients with normal immune systems. Our several patients with this process, all elderly women, developed self-limited encephalitis during the latter stages of an attack of shingles. They were confused and drowsy, with low-grade fever but little meningismus, and a few had seizures. Recovery was complete and the MRI was normal, in distinction to the vasculitic syndromes. In some reported cases, VZV has been isolated from the CSF and specific antibody to VZV membrane antigen (VAMA) has been found in the CSF and serum, although it is hardly needed for purposes of diagnosis. The differential diagnosis in these elderly patients also includes a drowsy confusional state induced by narcotics given for the control of pain. Varicella cerebellitis, a postor parainfectious condition, was discussed earlier in the chapter.
Finally, as mentioned earlier, a facial palsy or pain in the distribution of a trigeminal or segmental nerve (usually lumbar or intercostal) as a result of herpetic ganglionitis, may occur rarely without involvement of the skin (zoster sine herpete-see Gilden et al 1994); lumbar disc herniation may be suspected. In a few such cases, an antibody response to VZV has been found (Mayo and Booss), and Dueland and associates have described an immunocompromised patient who developed a pathologically and virologically proved zoster infection in the absence of skin lesions. Similarly, Gilden and colleagues (2002) recovered VZV DNA from two otherwise healthy immunocompetent men who had experienced chronic radicular pain without a zoster rash. But practically no instances of Bell’s palsy, tic douloureux, and intercostal neuralgia are associated with serologic evidence of activation of VZV (Bell’s palsy has instead been associated with HSV, as indicated in Chap. 44).
A cerebral angiitis that occasionally complicates VZV infection is histologically similar to granulomatosis with polyangiitis (formerly Wegener). Typically, 2 to 10 weeks after the onset specifically of ophthalmic zoster, the patient develops an acute hemiparesis, hemianesthesia, aphasia, or other focal neurologic or retinal deficits associated with a mononuclear pleocytosis in the spinal fluid and elevated IgG indices in the CSF. Nagel and colleagues have found that specific antibodies in the CSF to the virus were more sensitive for the diagnosis of this condition than was detection of viral DNA. CT or MRI scans demonstrate small, deep infarcts in the hemisphere ipsilateral to the outbreak of shingles on the face. Angiograms show narrowing or occlusion of the internal carotid artery adjacent to the ganglia; but in some cases, vasculitis is more diffuse, even involving the contralateral hemisphere (Hilt et al).
Whether the angiitis results from direct spread of the viral infection via neighboring nerves as postulated by Linnemann and Alvira, or represents an allergic reaction during convalescence from zoster, has not been settled. VZV-like particles have been found in the vessel walls, suggesting a direct infection and viral DNA has been extracted in a few cases from affected vessels. Because the exact pathogenetic mechanism is uncertain, treatment with both intravenous acyclovir and corticosteroids may be justified. There are occasional instances of a cerebral vasculitis following dermatomal zoster on the trunk.