Transient Olfactory Disturbance in Varicella Zoster Reactivation-A Case Report

Varicella zoster virus (VZV) is a highly contagious DNA virus, which causes varicella (chickenpox). After healing it persists in ganglionic neurons. Herpes zoster can occur in childhood after both wild-type childhood varicella and varicella vaccination. Due to several reasons, the virus can reactivate and cause zoster (shingles), which causes a battery of complications, for example, post-zoster neuralgia and meningoencephalitis including cerebellitis or vasculopathy. Only one case report including two men suffering from olfactory impairment and parosmia with Ramsey Hunt syndrome was published.1 Both suffered from loss of olfactory function and one patient reported additionally about parosmia. One patient reported spontaneous olfactory recovery after weeks, without exact time range. The other one reported olfactory recovery 3 weeks after therapy with chloramphenicol and vitamin B1.1 We report about a 15-year-old girl suffering from Ramsey Hunt syndrome. This patient additionally had olfactory impairment, which lasted for 6 months. A 15-year-old girl was hospitalized because of a peripheral facial nerve palsy (House-Brackmann-Score V). She complained about earache and vesicles on her right helix and retroauricular. The fallowing symptoms occurred: vertigo, ataxia, and horizontal nystagmus. Head impulse test showed a neuritis vestibularis. Audiometric evaluation resulted in a pathological hearing threshold on the right (5–10 dB). VZV IgG and IgM (DiaSorin, Saluggia, Italy) in blood were positive as well as VZV-PCR (Gold Standard Diagnostics, Freiburg, Germany) in cerebrospinal fluid (CSF) (7.11 × 103 copies/mL). Despite the varicella vaccination recommended in Germany since 2004, the child was unvaccinated against VZV. A mild varicella infection was reported at the age of four. Based on this, infection with wild-type VZV should be assumed. The MRI yielded no sign of possible inflammation. The diagnoses were zoster oticus with Ramsey Hunt syndrome, neuritis vestibularis dexter and zoster cerebellitis. Because of the multiple central involvements, olfactory testing was performed. Therefore, “Sniffin' Sticks” phenylethylalcohol (PEA) olfactory threshold test and “U-Sniff” odor identification test were conducted (Burghart Messtechnik, Holm, Germany).2 When asked about olfactory disturbance, the patient reported about phantosmia since the beginning of earache. Several times a day she would perceive the smell of “onion” or “cat food” without the presence of an odor source. The girl's olfactory threshold was determined at 3.5/16 points (Fig. 1A). During the testing olfactory threshold, the patient reported parosmic sensations (see Fig. 1A, B). All three “Sniffin' Sticks” of the testing triplet would smell like cheese or meat. Odor identification test was normal. Olfactory threshold was retested the following day but was similar to the first (Fig. 1B). The result of this olfactory threshold testing was 1/16 points (age-dependent border to hyposmia: 4.75 points). Because of zoster, therapy was started with Acyclovir intravenously and with oral prednisolone as decongestant. To treat hyposmia, we recommended olfactory training with four different odors each for 20 s twice a day for 6 months.3 Under therapy, clinical status improved, vertigo and nystagmus disappeared. Nevertheless, facial nerve palsy, gait insecurity, and parosmia were persistent at discharge from the hospital after 3 weeks. On a second visit 4 weeks later, the patient reported about persistent parosmia, with high intensity (8/10) and include unpleasant odors (onion, cat food). About 5% of all odors would be distorted in this parosmic sense. In olfactory testing with the “Sniffin' Sticks” test battery, olfactory threshold, odor discrimination and odor identification sum score (TDI) were still below the 10th percentile according to her age group 11–20 years with 28.5 points (T: 4.75, D: 14 points, I: 13; Fig. 1C). Although this test has been developed in adults, it can be assumed that it is applicable in postpubertal children because of their good executive function. Also, facial nerve palsy and gait insecurity were persistent. We recommended continuing olfactory training. After 6 months of olfactory training, there was an improvement in olfactory function (Fig. 1D). Using the “Sniffin' Sticks” test battery, the TDI score was 32.3 points (T: 6.3, D: 12, I:14), which indicates normosmia. Furthermore, parosmia ceased 5 months after infection. The patient reported about an improvement in facial nerve palsy and gait insecurity. This case shows that quantitative olfactory dysfunction as well as phantosmia and parosmia can present as a neurological complication of a zoster infection. So far only one case report of two adult men with olfactory loss and parosmia was reported in the 1950s.1 In two cases, the men suffered from olfactory loss while having a Ramsey Hunt syndrome. Patient 2 suffered from parosmia (e.g., garlic as resin). Smell improvement occurred spontaneously after 3 weeks in patient 1. In patient 2, smell loss improved after therapy with vitamin B1, chloramphenicol, and intranasal ephedrine application. Landis et al. reported a case series of three patients surviving herpes simplex encephalitis. These patients showed olfactory impairment. Two patients had functional anosmia in the follow-up of at least 3 years. The olfactory function of the third patient, a 10-year-old boy, initially was in the anosmic range after herpes simplex encephalitis and increased to hyposmia within 3 years after encephalitis.4 In the current case, an improvement in olfactory abilities after 6 months of olfactory training was observed. The pathophysiology of olfactory damage induced by VZV is unknown. In only 1% of the patients in a postmortem study, a VZV persistence in olfactory bulb cells was found.5 It is known that the olfactory mucosa has the potential to regenerate, which can be amplified by an odor-enriched environment. The present observations suggest that standardized olfactory testing should be conducted in patients suffering from Ramsey Hunt syndrome as well as zoster oticus or zoster ophthalmicus to evaluate whether olfactory disturbance is a complication in these pathologies. Olfactory disturbance is a possible complication of a zoster infection. Next to hyposmia also parosmia and phantosmia can be observed in patients suffering from Ramsey Hunt syndrome. We thank the patient and her parents for their participation and consent to publish this case report. Open Access funding enabled and organized by Projekt DEAL. The data that support the findings of this study are not publicly available due to containing information that could compromise the privacy of research participants but are available from the corresponding author Janine Gellrich in anonymized way upon reasonable request.