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Título

Intermediate Charcot-Marie-Tooth disease type C: A case report

RESUMO

Case presentation: A 31-year-old male with a history of progressive muscle weakness in four limbs for more than 20 years. He has 2 sisters and 1 maternal uncle with a similar condition. He denied dysphagia, respiratory complaints, or continuous use of medications. On examination, muscle strength was assessed in proximal and distal grade IV in all four limbs and deep tendon reflexes were hypoactive globally. Artresthesic and vibratory sensitivities were reduced in the lower limbs, while the superficial was reduced in the four limbs at the 10 Hz monofilament test. He had Gowers maneuver and gait with weakness of the gluteal muscles. There was no calf pseudohypertrophy, nervous hypertrophy or myotonia. Electroneuromyography (ENMG) revealed a moderate reduction in motor and sensory conduction velocities in the four limbs, with F waves abolished in ulnar and tibial nerves. In electromyography, voluntary contraction showed signs of chronic reinnervation with moderate rarefaction of motor units in the proximal muscles of upper limbs, and marked rarefaction in distal muscles of upper limbs and in proximal and distal muscles of lower limbs, describing a primarily demyelinating, sensory-motor, symmetrical, chronic polyneuropathy, with proximal and distal involvement, worse in the lower limbs. Vitamin B12, folic acid, infectious disease serology, metabolic panel, aldolase, ANA and anti-acetylcholine tests were normal. CPK was increased (990U/L). Genetic testing confirmed the diagnosis of intermediate type C Charcot-Marie-Tooth Disease (CMT) by mutation in the PLEKHG5 gene. Discussion: CMT is a group of genetic diseases that present as chronic and progressive motor and sensory neuropathy. The CMT1 and CMT2 subtypes are the most frequent and represent the demyelinating and axonal forms, respectively. The most common clinical presentation is distal weakness, atrophy, and sensory loss in a boot-and-glove pattern. In the present case, the patient has proximal weakness and intermediate motor nerve conduction velocity. The genetic test allowed the diagnosis of the intermediate type C form, an uncommon subtype characterized by mixed, axonal and demyelinating involvement. Final Considerations: CMT is described as the most common hereditary neuromuscular disease, and the intermediate type C form, a rare variant of the disease, was identified in this report. In many cases, the diagnosis still focuses on ENMG, but genetic testing is critical for confirmation.