Transient, Recurrent Central Nervous System Clinical Manifestations of X-Linked Charcot-Marie-Tooth Disease Presenting with Very Long Latency Periods between Episodes: Is Prolonged Sun Exposure a Provoking Factor?

Spatial Fluctuation of Central Nervous System Lesions in X-linked Charcot-Marie-Tooth Disease with a Novel GJB1 Mutation

X-linked Charcot-Marie-Tooth disease type 1 (CMTX1), the most common form of CMTX, is caused by gap-junction beta 1 (GJB1) mutations. We herein report a 25-year-old Japanese man with disorientation, right hemiparesis, and dysarthria. Brain magnetic resonance imaging (MRI) showed high signal intensities in the bilateral cerebral white matter on diffusion-weighted imaging. He had experienced 2 episodes of transient central nervous system symptoms (at 7 and 13 years old). A genetic analysis identified a novel GJB1 mutation, c.169C>T, p.Gln57*. MRI abnormalities shifted from the cerebral white matter to the corpus callosum and had disappeared at the five-month follow-up. Transient changes between these lesions may indicate CMTX1.

Clinical and electrophysiological characteristics of women with X-linked Charcot-Marie-Tooth disease

BACKGROUND

X-Linked Charcot-Marie-Tooth disease type 1 (CMTX1) is characterized by gender differences in clinical severity. Women are usually clinically affected later and less severely than men. However, their clinical presentation appears to be heterogenous. Our aim was to extend the phenotypic description in a large series of women with CMTX1.

METHODS

We retrospectively evaluated 263 patients with CMTX1 from 11 French reference centers. Demographic, clinical, and nerve conduction data were collected. The severity was assessed by CMT Examination Score (CMTES) and Overall Neuropathy Limitations Scale (ONLS) scores. We looked for asymmetrical strength, heterogeneous motor nerve conduction velocity (MNCV), and motor conduction blocks (CB).

RESULTS

The study included 137 women and 126 men from 151 families. Women had significantly more asymmetric motor deficits and MNCV than men. Women with an age of onset after 19 years were milder. Two groups of women were identified after 48 years of age. The first group represented 55%, with women progressing as severely as men, however, with a later onset age. The second group had mild or no symptoms. Some 39% of women had motor CB. Four women received intravenous immunoglobulin before being diagnosed with CMTX1.

CONCLUSIONS

We identified two subgroups of women with CMTX1 who were over 48 years of age. Additionally, we have demonstrated that women with CMTX can exhibit an atypical clinical presentation, which may result in misdiagnosis. Therefore, in women presenting with chronic neuropathy, the presence of clinical asymmetry, heterogeneous MNCV, and/or motor CB should raise suspicion for X-linked CMT, particularly CMTX1, and be included in the differential diagnosis.

Systematic review of CMTX1 patients with episodic neurological dysfunction

OBJECTIVE

X-linked Charcot-Marie-Tooth type 1 (CMTX1) is an inherited peripheral neuropathy caused by mutations in the gap junction beta 1 (GJB1) gene, which encodes the connexin32 protein. A small number of patients with GJB1 mutations present with episodic neurological dysfunction and reversible white matter lesions, which has not been adequately reported. Here, we aim to enable clinicians to further understand this particular situation through systematically reviewing all published relevant cases.

METHODS

We conducted a comprehensive search of the PubMed electronic database for medical literature relevant to CMTX1 patients with episodic neurological dysfunction and then fully analyzed the general information, clinical manifestations, and characteristics of magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, and nerve conduction study (NCS).

RESULTS

We identified 47 cases of CMTX1 associated with episodic central nervous system (CNS) dysfunction from 38 publications. CMTX1 patients experienced episodic CNS deficits at a young age, ranging from infancy to 26 years, and 45 (95.7%) of them were male. The CNS symptoms manifested as facial, lingual, or limb weakness in 44 (93.6%), dysarthria or dysphagia in 39 (83.0%), facial or limb numbness in 15 (31.9%), and ataxia in 10 (21.3%) patients. The duration of episodic symptoms ranged from 3 minutes to 6 months. Thirty (63.8%) CMTX1 cases have reported obvious predisposing factors, among which the most common factors were infection or fever (27.7%), travel to high altitude (12.8%), and intensive exercise (8.5%). As for brain MRI, most abnormal signals were found in bilateral deep white matter (88.9%) and corpus callosum (80.0%). In addition, most of the NCS results were abnormal, including prolonged latency, reduced amplitude, and slowed conduction velocity. The motor nerve conduction velocity (MNCV) of median nerve was the most detectable and valuable, ranging from 25 to 45 m/s.

INTERPRETATION

We have reported the most comprehensive summary of the demographic and clinical profile from 47 CMTX1 patients with episodic CNS deficits and provided new insight into the phenotype spectrum of CMTX1. We hope that our study can help clinicians make early diagnosis and implement the best prevention and treatment strategies for CMTX1 patients with episodic CNS deficits.