Differentials
Diabetic neuropathy
SIGNS / SYMPTOMS
The most common cause of neuropathy, normally seen in adults.
INVESTIGATIONS
Fasting plasma glucose: ≥126 mg/dL.
Oral glucose tolerance test: 2-hour postglucose load ≥200 mg/dL.
HbA1c: >6%.
Chronic inflammatory demyelinating polyneuropathy
SIGNS / SYMPTOMS
Symmetrical polyneuropathy involving both distal and proximal muscles. Usually more rapidly progressive than Charcot-Marie-Tooth disease with an acute onset.
INVESTIGATIONS
Sural nerve biopsy: may show inflammation in addition to demyelination.
Acquired peripheral neuropathy
SIGNS / SYMPTOMS
Causes include toxins, hypothyroidism, vitamin deficiencies, and renal failure.
As with Charcot-Marie-Tooth (CMT) disease, deep tendon reflexes are diffusely absent or reduced.
Timeline of symptom onset and the past medical history help to differentiate this condition from CMT.
INVESTIGATIONS
Investigations and results dependent on the underlying cause.
Fasting plasma glucose: ≥126 mg/dL in diabetes mellitus.
Oral glucose tolerance test: 2-hour postglucose load ≥200 mg/dL in diabetes mellitus.
BUN and creatinine: may show chronic renal impairment.
Liver function tests: deranged in hepatitis, toxin ingestion.
Thyroid function tests: thyroid-stimulating hormone (TSH) elevated, free thyroxine (T4) and free triiodothyronine (T3) reduced in hypothyroidism.
Erythrocyte sedimentation rate and C-reactive protein: elevated in systemic lupus erythematosus, mononeuritis multiplex.
Serum B12: reduced in vitamin B12 deficiency.
Hereditary spastic paraplegia (HSP)
SIGNS / SYMPTOMS
Spasticity, hyperreflexia, and Babinski signs are indicative of an upper motor neuron lesion. Central nervous system manifestations, including upper motor neuron signs, are uncommon in Charcot-Marie-Tooth disease.
INVESTIGATIONS
Genetic testing: specific gene mutation known to cause HSP.
MRI: atrophy of spinal cords, possible atrophy of cerebral cortex.
Spinocerebellar degeneration
SIGNS / SYMPTOMS
Ataxia is a major component of the symptomatology, but some patients have an associated neuropathy.
INVESTIGATIONS
MRI: spinocerebellar degeneration.
Use of this content is subject to our disclaimer