Charcot Ankle Arthropathy in CMT1A Exacerbated by Type 2 Diabetes Mellitus

Charcot neuroarthropathy in patients with Charcot Marie Tooth Disease

Charcot Marie Tooth disease (CMT) is the most common inherited neuropathy and is also called Hereditary Motor Sensory Neuropathy (HMSN). Whilst both motor and sensory deficits are present, motor deficits tend to predominate over sensory deficits. Charcot neuroarthropathic joints occur in conditions, most commonly diabetes nowadays, where joints are destroyed in association with reduced protective sensation, pain in particular. Three cases of development of Charcot joint disorders in patients with CMT are discussed and the literature is reviewed. Orthopaedic surgeons should be aware that Charcot joints can occur in CMT and surgery can be complicated by Charcot joints.

Coexistence of Charcot Marie Tooth disease type 1A and diabetes in Taiwan: A clinicopathological study

BACKGROUND

Charcot Marie Tooth disease type 1A (CMT1A) is the most commonly inherited demyelinating polyneuropathy with variable phenotypes, affected by several comorbidities, especially diabetes mellitus (DM). Previous studies showed that DM exacerbates the clinical manifestations of CMT1A.

PATIENTS AND METHODS

We retrospectively evaluated patients with CMT1A in our hospital, and identified three groups among 12 cases, which comprised four patients with CMT1A, four with CMT1A+DM, and four with DM. We reviewed the CMT neuropathy score (CMTNS), electrophysiological data, and histomorphological parameters of the sural nerve, including fiber density, myelin thickness, axon diameter, g-ratio, regenerative clusters, and regeneration ratio.

RESULTS

The CMTNS was significantly higher in patients with CMT1A+DM (21.5±2.52) than in those with CMT1A only (10.8±4.4; p=0.03). Pathological findings in patients with CMT1A+DM included a significant decrease of myelinated fiber density (p=0.02) and reduction in the regenerative ratio (p=0.01), indicating severe degeneration with impaired regeneration. In non-parametric analyses, DM was found to play a more important role than CMT1A in influencing nerve degeneration and regeneration.

CONCLUSIONS

In patients with CMT1A, DM exacerbated clinical and pathological manifestations including increased loss of myelinated fibers, abnormal axon-myelin interaction, and impaired nerve regeneration.

Influence of comorbidities on the phenotype of patients affected by Charcot-Marie-Tooth neuropathy type 1A

Charcot-Marie-Tooth type 1A (CMT1A) is the most common inherited neuropathy. The phenotype of patients affected by CMT1A is highly variable and may be influenced by several conditions. We evaluated how comorbidities such as diabetes, hypothyroidism, exposure to toxins and obesity can modify or exacerbate the clinical and neurophysiological phenotype of CMT1A patients. Disability was measured using the classic CMT neuropathy score. Compared to controls, all groups of CMT1A patients with comorbidities had higher CMT neuropathy score. In particular, patients with CMT1A and diabetes mellitus show motor subscores which are significantly higher than in control CMT1A. Amplitudes of ulnar CMAP are lower in patients with CMT1A and diabetes mellitus, but not at a significant level. As expected, motor nerve conduction velocity is not influenced by any of the comorbidities. The presence of concomitant diseases shows a tendency to worsen the clinical and neurophysiological CMT1A phenotype, especially in patients with CMT1A and diabetes mellitus, where higher values in the CMT neuropathy score and clinical motor subscore have been observed.