Cutaneous Sensibility Changes in Bell's Palsy Patients

Sensory function in the faces of patients with facial palsy: A prospective observational study using quantitative sensory testing

Objectives/Hypothesis

To determine the sensory function of both sides of the face in patients with acute or chronic facial palsy.

Study design

Prospective observational study.

Methods

The standardized quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain (DFNS), including thermal or mechanical stimuli (touch, pain, vibration, and pressure), was used to investigate somatosensory function in the faces of patients. A patient-reported outcome measures for the assessment of disturbed facial comfort or facial pain, the facial Clinimetric Evaluation Scale (FaCE) Facial Comfort Subscale, and the 36-Item Short Form Survey (SF-36) pain subdomain were used.

Results

A total of 29 patients (22 female, median age of 48 years; 7 acute palsy; 22 chronic palsy; House-Brackmann grade II-VI) were included. The median FaCE Facial Comfort Subscale score and the median SF-36 pain subdomain score were 50 and 100, respectively. Most patients had, at an individual level, a normal sensory function in all or most tests. On average, the frequencies for all parameters were not different between the paretic side and the contralateral side (all p > 0.05). Additionally, when z-scores were used to compare our patient sample with healthy controls from the DFNS reference database, there was no difference between the paretic side and the contralateral side (all p > 0.05). Furthermore, there were no differences between patients with acute facial palsy and those with chronic facial palsy (all p > 0.05). The FaCE Facial Comfort Subscale score and the SF-36 pain subdomain score did not correlate with the QST parameters (all p > 0.05).

Conclusion

Patients with acute or chronic unilateral peripheral facial palsy had normal sensory function on the paretic and contralateral sides compared with the reference values of healthy controls, and there was no significant difference between the sides. The numbness frequently felt in the affected hemiface is not related to a peripheral sensory disorder and is most likely a manifestation of an unsolved cortical somatosensory-motor mismatch.

Case report: Bitter vertigo

Background

There are many causes of episodes of vertigo and very few causes of episodes of changes in taste, and the combination of the two is very rare. Here, we describe a patient with recurrent short episodes of vertigo in combination with simultaneous episodes of recurrent paroxysmal dysgeusia and altered feeling on the left side of face. The symptoms were caused by compression of the vestibulocochlear nerve and the facial nerve due to dolichoectasia of the basilar artery.

Methods

The patient was diagnosed in our routine clinical practice and underwent a complete neurological and neuro-otological examination, including video head impulse test, caloric irrigation, ocular and cervical vestibular evoked myogenic potentials, acoustic-evoked potentials, neuro-orthoptic examination, cranial MRI, and MR angiography. The patient was seen twice for follow-up.

Case

A 71-year-old patient primarily presented with a 2-year history of recurrent short episodes of spinning vertigo. Each of the episodes began with an altered feeling on the left side of the face, followed by a bitter taste on the left half of the tongue, and subsequently vertigo lasting for up to 15 s. The frequency of the attacks was high: up to 80 times per day. Laboratory tests revealed signs of a peripheral vestibular deficit on the left side. There were no signs of sensory or motor deficits or of altered taste between the episodes. An MRI of the brain showed an elongated basilar artery leading to an indentation of the facial and vestibulocochlear nerves on the left side.

Conclusion

We propose a neurovascular compression in the proximal part of two cranial nerves because of pulsatile compression by the elongated basilar artery with ephatic discharges as the cause of the recurrent episodes. Consistent with the theory of ephatic discharges, treatment with the sodium channel blocker lacosamide for over six months with a final dosage of 200 mg per day p.o. led to a significant reduction of the attack frequency and intensity. This treatment option with a sodium channel blocker should therefore not only be considered in vestibular paroxysmia but also in cases of paroxysmal dysgeusia.

Newly identified axon types of the facial nerve unveil supplemental neural pathways in the innervation of the face

INTRODUCTION

Neuromuscular control of the facial expressions is provided exclusively via the facial nerve. Facial muscles are amongst the most finely tuned effectors in the human motor system, which coordinate facial expressions. In lower vertebrates, the extracranial facial nerve is a mixed nerve, while in mammals it is believed to be a pure motor nerve. However, this established notion does not agree with several clinical signs in health and disease.

OBJECTIVES

To elucidate the facial nerve contribution to the facial muscles by investigating axonal composition of the human facial nerve. To reveal new innervation pathways of other axon types of the motor facial nerve.

METHODS

Different axon types were distinguished using specific molecular markers (NF, ChAT, CGRP and TH). To elucidate the functional role of axon types of the facial nerve, we used selective elimination of other neuronal support from the trigeminal nerve. We used retrograde neuronal tracing, three-dimensional imaging of the facial muscles, and high-fidelity neurophysiological tests in animal model.

RESULTS

The human facial nerve revealed a mixed population of only 85% motor axons. Rodent samples revealed a fiber composition of motor, afferents and, surprisingly, sympathetic axons. We confirmed the axon types by tracing the originating neurons in the CNS. The sympathetic fibers of the facial nerve terminated in facial muscles suggesting autonomic innervation. The afferent fibers originated in the facial skin, confirming the afferent signal conduction via the facial nerve.

CONCLUSION

These findings reveal new innervation pathways via the facial nerve, support the sympathetic etiology of hemifacial spasm and elucidate clinical phenomena in facial nerve regeneration.