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Myofibrillar Myopathy Mimicking Polyneuropathy
Pierre R Bourque1,2, Ari Breiner1,2, Jodi Warman-Chardon1,2,3
1Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Ontario, Canada.
Case Reports in Neurology
|July 11, 2020
Summary
This study identifies a genetic mutation in myotilin causing both neuropathy and myopathy, presenting as unexplained foot drop. Whole-body muscle MRI and genetic testing can aid in diagnosing this rare condition.
Area of Science:
- Neurology
- Genetics
- Musculoskeletal Disorders
Background:
- A 76-year-old man presented with a 5-year history of gait difficulties and foot drop.
- Initial electrodiagnostic studies suggested a neurogenic etiology for foot drop, but showed prominent myotonic discharges on needle electromyography (EMG).
- Standard tests for acquired and genetic polyneuropathies were inconclusive.
Observation:
- The patient's cousin had a diagnosis of myofibrillar myopathy.
- The patient was found to carry the c.179C>T p.Ser60Phe mutation in the myotilin gene, identical to his cousin.
- Muscle MRI revealed unexpected involvement of paraspinal and pelvic muscles, alongside significant fatty infiltration in distal leg muscles, indicative of myopathy.
Findings:
- The co-occurrence of neuropathy and myopathy is a known characteristic of myofibrillar myopathy.
- The identified myotilin mutation links the patient's neurological and muscular symptoms.
- Muscle MRI proved valuable in identifying subclinical muscle involvement.
Implications:
- This case highlights the importance of considering genetic myopathies in patients with unexplained neuropathy, particularly foot drop.
- Whole-body muscle MRI and targeted genetic testing are crucial diagnostic tools for uncovering genetic myopathies.
- Early diagnosis of myofibrillar myopathy can potentially guide management and genetic counseling.
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