Possible association of herpes simplex virus infection with demyelinating disease

Administration of herpes simplex virus (HSV) in sublethal doses to experimental animals may cause a relapsing demyelination in the central nervous system (CNS) but will leave the peripheral myelin unimpaired. Demyelination will be followed by remyelination by oligodendroglial cells or by invading Schwann cells. Relapsing episodes of CNS demyelination seen in HSV latently infected animals may be caused either by reactivation of HSV residing in the CNS itself or virus transported to the CNS after reactivation of a latent infection in peripheral sensory or autonomic ganglia. Although HSV is not the only virus known to induce a demyelination in the CNS of experimental animals, the similarities of this HSV induced demyelination and multiple sclerosis (MS) are intriguing, albeit an association of HSV reactivation and MS has not as yet been reported. However, circumstantial evidence for HSV induction of restricted CNS demyelination in man has recently been obtained: Several laboratories have reported on association of HSV with acute idiopathic facial palsy (Bell's palsy). If HSV be the cause of this palsy, the site of a lesion giving the nerve dysfunction should be located in the brain stem of the CNS rather than in the extrapontine part of the facial nerve. Indeed, most of Bell's palsy patients studied had signs of a brain stem disorder revealed by either one or more of the following tests: auditory brain stem response test, trigeminal evoked potential test or extensive clinical neurological examination. Furthermore, 35% of patients with Bell's palsy had increased concentrations of myelin basic protein in the cerebrospinal fluid collected in the acute stage of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)