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Non-demyelinating, reversible conduction failure in a case of pharyngeal–cervical–brachial weakness overlapped by Fisher syndrome

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Abstract

Pathophysiologically, Guillain–Barré syndrome is divided into demyelinating and axonal subtypes. Recent studies have shown that serial nerve conduction studies (NCSs) are required to differentiate a demyelination–remyelination pathophysiology from one with axonal nodal reversible conduction failure. Cases with an overlap of pharyngeal–cervical–brachial weakness and Fisher syndrome (PCB/FS) are uncommon; the NCS findings of such cases have not been well described and the evolution of the NCS findings has not been previously studied. We describe the clinical features and serial NCS findings of a patient with PCB/FS. The evolution of abnormalities in NCS reflected a clinical pattern of weakness that progressed from the top of the body and descended toward the legs, and terminated before reaching the legs. The amplitudes of motor and sensory potentials were decreased, as is consistent with acute motor-sensory axonal neuropathy. However, the amplitudes recovered without the appearance of dispersed potentials seen in remyelination, implicating the pathophysiology of nodal reversible conduction failure. Together with the electrophysiological evidence of the pathophysiology of nodal reversible conduction failure in previously reported PCB patients and FS patients, our case suggests that PCB, FS and PCB/FS fall in a continuous spectrum with axonal GBS subtypes.

Introduction

Patients with Guillain–Barré syndrome (GBS) typically present with symmetrical weakness of both upper and lower limbs, along with generalized areflexia. Ropper [1] first reported 3 patients who developed prominent weakness in the pharyngeal–cervical–brachial regions without sensory disturbance. Their illnesses ended without affecting the power of their legs. He called this condition pharyngeal–cervical–brachial weakness (PCB) and considered this an abortive form of GBS that did not progress to cause generalized weakness. He further described another patient who had ophthalmoplegia, ataxia and generalized areflexia, in addition to PCB, and suggested that it was a case of PCB overlapped by Fisher syndrome (PCB/FS) [2]. Because the clinical features of PCB and PCB/FS are similar to those of myasthenia gravis and botulism, nerve conduction studies (NCSs) are useful in differential diagnosis.

Pathophysiologically, GBS is divided into demyelinating and axonal subtypes [3], [4]. Conduction block seen in NCS has classically been deemed a feature of demyelination. However, recent studies suggest that conduction block or slowing can also be due to conduction failure from immune-mediated disruptions at the nodes of Ranvier without internodal demyelination [5], [6], [7]. The conduction block or slowing resolves promptly with the reversal of conduction failure at the nodes without development of excessive temporal dispersion characteristic of remyelination [8], [9]. Thus, serial NCSs are required to differentiate between a demyelination and remyelination pathophysiology from one with axonal, reversible conduction failure [8], [9]. NCS findings in PCB/FS have not been well described and the evolution of abnormalities has not been previously studied. Here, we report the clinical features and serial NCS findings in a PCB/FS patient whose NCS results implicate a pathophysiology of axonal reversible conduction failure.

Section snippets

Case report

One week after recovering from a mild diarrheal illness, a 61-year-old lady was admitted. She reported a 1-day history of non-vertiginous dizziness and finger paresthesia that was maximal at the fingertips bilaterally. Initial examination revealed mild gait ataxia but no other neurological abnormality. In particular, Romberg test and tendon reflexes were normal. A CT brain showed no relevant abnormality.

Examination on the next day showed dysarthria, dysphagia, external ophthalmoplegia and arm

Discussion

Our patient's clinical presentation is consistent with PCB/FS, although other differentials were also considered. The acute onset of symptoms initially led us to consider brainstem vascular ischemia or hemorrhage, but the presence of generalized areflexia, symmetrical bilateral weakness and ophthalmoplegia, together with bulbar weakness and preserved consciousness, was inconsistent with these diagnoses. Myasthenia gravis was also considered, but the sudden occurrence of onset, absence of

Authors' contributions

Study concept and design: Drs. Chan and Yuki.

Analysis and interpretation: Drs. Chan, Aftab, Prakash and Yuki.

Drafting of the manuscript: Drs. Chan, Aftab and Prakash.

Critical revision of the manuscript for important intellectual content: Drs. Chan and Yuki.

Study supervision: Dr. Yuki.

Conflict of interest

This study was supported in part by Yong Loo Lin School of Medicine Start-up Grant (Nobuhiro Yuki) and the National Medical Research Council (IRG 10 Nov 086), Ministry of Health, Singapore. The authors have no other conflict of interest.

Financial disclosure

None reported.

Funding/support

This study was supported in part by Yong Loo Lin School of Medicine Start-up Grant (Nobuhiro Yuki) and the National Medical Research Council (IRG 10 Nov 086), Ministry of Health, Singapore.

Acknowledgment

We are grateful to Dr. Benjamin Wakerley and Dr. Norito Kokuban for their suggestions and critical reading of the manuscript, Ms Tan Shuyu for her editorial assistance and Mr. Aravinda Therimadasamy and Ms. Eileen Li for producing the figures.

References (21)

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