Acute herpes zoster neuropathy

Acute zoster-associated pain develops in most patients with herpes zoster. Nonopioid analgesics are usually used to treat acute zoster-associated pain but are frequently ineffective. We administered intravenous fosphenytoin, the prodrug of phenytoin, to patients with acute zoster-associated pain to examine its analgesic efficacy and safety. At 13 medical institutions in Japan, we conducted a phase II, double-blind, placebo-controlled, randomized trial of intravenous fosphenytoin in Japanese inpatients with acute zoster-associated pain for whom nonopioid analgesics had shown an insufficient analgesic effect. The patients were randomly assigned (1:1:1) to receive a single intravenous dose of fosphenytoin at 18 mg/kg (high dose), a single intravenous dose of fosphenytoin at 12 mg/kg (low dose), or placebo. The primary endpoint was the mean change per hour (slope) in the numerical rating scale score from the baseline score until 120 min after dosing. Seventeen patients were randomly assigned to the low-dose fosphenytoin group (n = 6, median age 62.5 years, range 39-75 years), high-dose fosphenytoin group (n = 5, median age 69.0 years, range 22-75 years), and placebo group (n = 5, median age 52.0 years, range 38-72 years). One patient was excluded because of investigational drug dilution failure. This study was discontinued because of the influences of coronavirus disease 2019. The slope was significantly lower in the high- and low-dose fosphenytoin groups than in the placebo group (P < 0.001 and P = 0.016, respectively). Responsiveness to intravenous fosphenytoin (≥2-point reduction in the numerical rating scale score from baseline to 120 min after dosing) was inferred at plasma total phenytoin concentrations of 10-15 μg/mL. Treatment-emergent adverse events caused no safety concerns in the clinical setting and intravenous fosphenytoin was well tolerated. Intravenous fosphenytoin appears to be an effective and promising alternative treatment for acute zoster-associated pain. Trial Registration: ClinicalTrials.gov NCT04139330.

Varicella zoster virus (VZV) causes chickenpox at the primary infection and then becomes latent in the spinal dorsal root ganglia; VZV can reactivate with aging, immunosuppression, stress, and other factors, occurring as herpes zoster (HZ) at 1-2 skin segments. HZ peripheral nerve complications caused by VZV reactivation include Hunt syndrome, segmental HZ paresis, post-herpetic neuralgia, and Guillain-Barré syndrome (GBS). We have encountered the rare HZ complications of upper-limb paresis, myeloradiculitis, and polyradiculoneuritis: an adult woman with upper-limb paresis consistent with the nerve root on segments above the thoracic HZ dermatome; another woman exhibiting ascending myeloradiculitis originating at the Th11-12 roots; an elderly woman with ascending VZV polyradiculoneuritis resembling GBS; an adult with VZV quadriplegia with disseminated HZ; and an elderly patient with VZV-associated polyradiculoneuritis. The three polyradiculoneuritis cases may be a new subtype of HZ peripheral neuropathy, but the pathophysiology for these HZ peripheral nerve complications unrelated to HZ dermatomes is unclear. We analyzed host factors, skin lesions, neurological and virological findings, and MRI results including 3D NerveVIEW in 15 Japanese patients treated at our facility for HZ peripheral neuropathy, including six differing from the HZ dermatome. Based on the clinical findings including MRI results of spinal ganglia and roots, we identified four possible routes for the patterns of VZV spread: (i) ascending spinal roots, (ii) ascending spinal cord, (iii) polyradiculopathy, and (iv) intrathecal spread. The incidence of HZ is increasing with the aging of many populations, and clinicians should be aware of these HZ neuropathies.

A case report of varicella zoster virus (VZV) producing cranial polyneuropathy with intracranial vasculopathy afflicting the internal carotid artery, in a 45-year lady is presented. The clinical features included appearance of zosteriform rash in the left external auditory canal and concha, affliction of ophthalmic and maxillary divisions of V, VI, VII, VIII, IX and X cranial nerves. Contrast MRI brain demonstrated attenuated flow void in the left internal carotid artery. The diagnosis was confirmed with raised level of IgG VZV antibody in serum and detection of VZV IgG antibody in CSF, although PCR for VZV DNA in CSF was negative. The significance lies in atypical presentation, the diagnostic dilemma it poses, poor prognosis of cranial nerve function and the need for multidisciplinary approach to patient management and rehabilitation.