Peripheral neuropathies

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Target exams

Red flags

• A child receiving vincristine for leukaemia who develops severe acute neuropathy may have undiagnosed Charcot-Marie-Tooth disease; check for pes cavus and family history before the first dose, because vincristine can cause irreversible paralysis in CMT
• Progressive symmetric weakness over more than eight weeks with areflexia and demyelinating nerve conduction studies is chronic inflammatory demyelinating polyradiculoneuropathy until proven otherwise, not a slow Guillain-Barre syndrome, and it responds to corticosteroids unlike Guillain-Barre syndrome
• A child with pes cavus, hammer toes, and distal leg wasting almost certainly has an inherited neuropathy, and the single most useful bedside question is whether anyone in the family has high arches, foot drop, or abnormal gait
• Recurrent painless focal palsies after minor compression, such as wrist drop after leaning on a desk, point to hereditary neuropathy with liability to pressure palsies from a PMP22 deletion
• Median motor nerve conduction velocity under thirty-eight metres per second with uniform slowing across all nerves distinguishes CMT1 demyelinating disease from acquired demyelination, which shows patchy non-uniform conduction block

Life stages

Care settings

Clinical exam formats

Board mappings

• Recognises Charcot-Marie-Tooth disease as the commonest inherited neuropathy of childhood with prevalence around one in two thousand five hundred and describes the phenotype of distal wasting, pes cavus, foot drop, and areflexia
• States that CMT1A is caused by a PMP22 duplication on chromosome seventeen and that nerve conduction velocity under thirty-eight metres per second indicates a demyelinating neuropathy
• Identifies that chronic inflammatory demyelinating polyradiculoneuropathy progresses over more than eight weeks and responds to corticosteroids and intravenous immunoglobulin unlike Guillain-Barre syndrome
• Distinguishes the demyelinating CMT1 with uniform slowing from the axonal CMT2 and the X-linked CMTX1 with GJB1 connexin 32 variants using nerve conduction studies and targeted genetic testing
• Applies the Yiu 2022 paediatric Charcot-Marie-Tooth clinical practice guideline for orthotic, surgical, and rehabilitation management and recognises that no disease-modifying therapy has proven effective for CMT1A
• Recognises that vincristine can unmask or severely worsen Charcot-Marie-Tooth disease and that genetic neuropathies can present with chronic inflammatory demyelinating polyradiculoneuropathy-like features in childhood
• The Charcot-Marie-Tooth classification into demyelinating CMT1, axonal CMT2, and intermediate types with their major genes PMP22, MPZ, MFN2, and GJB1
• The nerve conduction study distinction: uniform slowing under thirty-eight metres per second for CMT1 versus reduced amplitudes with preserved velocity for CMT2
• The chronic inflammatory demyelinating polyradiculoneuropathy criterion of progression over more than eight weeks and its treatment with intravenous immunoglobulin, corticosteroids, and plasma exchange
• Assesses a child with progressive distal weakness and foot deformity, interprets nerve conduction studies, and constructs a multidisciplinary management plan with orthotics, physiotherapy, and genetic counselling
• Distinguishes hereditary from acquired neuropathy using the family history, the tempo, the symmetry, and the nerve conduction pattern, and identifies treatable acquired causes
• Counsels the family on inheritance, prognosis, the role of genetic testing, and the implications for anaesthesia and chemotherapy including the vincristine contraindication in Charcot-Marie-Tooth disease
• Level 1: Recognition that pes cavus, distal leg wasting, and areflexia in a child suggest an inherited neuropathy and that a family history of foot deformity strengthens the diagnosis
• Level 2: Application of nerve conduction studies to distinguish demyelinating from axonal neuropathy and knowledge of the common Charcot-Marie-Tooth genes
• Level 3: Multidisciplinary management using the paediatric guideline, identification of treatable acquired neuropathies, and genetic counselling including reproductive implications
• Charcot-Marie-Tooth disease as the commonest inherited neuromuscular disorder with CMT1A from PMP22 duplication causing demyelination and CMT2A from MFN2 causing axonal disease
• The nerve conduction velocity threshold of thirty-eight metres per second to separate demyelinating from axonal neuropathy and the concept of uniform versus patchy slowing
• Chronic inflammatory demyelinating polyradiculoneuropathy as an acquired treatable neuropathy progressing over more than eight weeks, responsive to corticosteroids and intravenous immunoglobulin
• Examination of the feet, gait, reflexes, and sensation in a child with suspected neuropathy, and the identification of pes cavus, hammer toes, and distal wasting
• Interpretation of nerve conduction studies and targeted genetic testing, and the construction of a management plan with ankle-foot orthoses and physiotherapy
• Communication of the diagnosis, inheritance pattern, prognosis, and the need to avoid vincristine in Charcot-Marie-Tooth disease
• Charcot-Marie-Tooth disease as the commonest inherited peripheral neuropathy in United States children with autosomal dominant CMT1A from PMP22 duplication
• The clinical features of distal muscle wasting, pes cavus, foot drop, steppage gait, and impaired proprioception and vibration with relative sparing of pain and temperature
• The acquired neuropathies including chronic inflammatory demyelinating polyradiculoneuropathy, diabetic neuropathy, and chemotherapy-induced peripheral neuropathy from vincristine
• Recognition of the inherited neuropathy phenotype and the role of family history and nerve conduction studies in classification
• Identification of treatable acquired neuropathies including chronic inflammatory demyelinating polyradiculoneuropathy and diabetic neuropathy in youth
• The vincristine precaution in suspected Charcot-Marie-Tooth disease and the multidisciplinary management with orthotics, physiotherapy, and surgery
• Canadian approach to the classification and genetic diagnosis of Charcot-Marie-Tooth disease using nerve conduction studies and next-generation sequencing panels
• The distinction between hereditary uniform slowing and acquired patchy demyelination on nerve conduction studies
• Management using the paediatric guideline with ankle-foot orthoses, surgical correction, and genetic counselling, and the recognition of treatable acquired neuropathies