Clinical and Electrophysiological Findings in Hereditary Inclusion Body Myopathy Compared With Sporadic Inclusion Body Myositis

Kazamel, Mohamed; Sorenson, Eric J.; Milone, Margherita

doi:10.1097/cnd.0000000000000113

Cited by 13 publications

(16 citation statements)

References 36 publications

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“…Myotonic discharges may occur to a minimal degree in the setting of active denervation but are more typical of channelopathies and dystrophic myotonias [7]. They have been described in a wide range of other myopathies, notably the inflammatory myopathies [8] and acid maltase deficiency [9]. They may also occur to be a characteristic feature of myofibrillar myopathies [10].…”

Section: Discussionmentioning

confidence: 99%

Myofibrillar Myopathy Mimicking Polyneuropathy

2020

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A 76-year-old man with a 5-year history of gait difficulties was suspected to have length-dependent sensorimotor polyneuropathy. Electrodiagnostic results pointed to a foot drop of neurogenic etiology, except for the prominence of myotonic discharges on needle EMG. Tests for acquired and genetic causes of polyneuropathy were unrevealing. The patient's first-degree cousin, with a much different clinical phenotype had been diagnosed with myofibrillar myopathy. Our patient was eventually found to carry the same myotilin c.179C>T p.Ser60Phe mutation. Muscle MRI was helpful in delineating clinically unsuspected involvement of paraspinal and pelvi-femoral muscles, as well as showing marked myopathic fatty infiltration of distal leg muscles. The association of neuropathy and myopathy is a recognized feature of myofibrillar myopathy. In some patients with unexplained foot drop, whole-body muscle MRI and a dedicated genetic mutation testing strategy may help reveal a diagnosis of genetic myopathy.

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Section: Discussionmentioning

confidence: 99%

Myofibrillar Myopathy Mimicking Polyneuropathy

2020

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“…hIBM can be differentiated from sIBM as the latter (1) typically presents at an older age, (2) more commonly has dysphagia, (3) often involves the quadriceps, (4) is more frequently asymmetric, (5) is more likely to have increased CK, (6) and has more inflammatory/immune-related changes on biopsy. 4,5,7 There are several types of hIBM. 8 Nonaka myopathy (GNE mutation) often presents at a young age involving the distal anterior leg compartment.…”

Section: Discussionmentioning

confidence: 99%

Clinical Reasoning: A 40-year-old woman presenting with distal leg weakness

et al. 2019

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A 40-year-old Caucasian woman reported 15 years of progressive lower leg and hand weakness. Weakness began asymmetrically in the legs. She had trouble standing on her toes and developed progressive bilateral foot drop, worse on the right. Over the years, she developed difficulty arising from low seats and climbing stairs. She began falling with her knees buckling bilaterally. She was a hairstylist, but stopped working about 2 years prior after the onset of weakness in her hands, including difficulty opening jars or using scissors. These symptoms progressed insidiously over the years without fluctuation.The patient's medical history was unremarkable and she was not taking medications. Neurologic review of systems was negative for visual changes, dysphagia, dysarthria, pain, stiffness, sensory changes, or bowel/bladder dysfunction. She also denied dyspnea, myalgias, exercise intolerance, or myoglobinuria. All childhood developmental milestones were appropriate. Her parents were not consanguineous and there was no reported family history of weakness or symptoms of nerve or muscle disease.

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“…Myotonic discharges are nearly universal in DM1, but clinical and even electrical myotonia can be subtle or lacking in DM2 114,115 . Moreover, waning‐only myotonic discharges, complex repetitive discharges, and fibrillation potentials can occur in both DM2 and sIBM, 115,116 requiring careful differentiation between these two disorders. Myotonic discharges can also occur in other myopathies (including sIBM, vacuolar myopathies, or myofibrillar myopathies), 116,117 and are frequently found in paraspinal muscles in Pompe disease 118 .…”

Section: Electrodiagnostic Findingsmentioning

confidence: 99%

“…Moreover, waning‐only myotonic discharges, complex repetitive discharges, and fibrillation potentials can occur in both DM2 and sIBM, 115,116 requiring careful differentiation between these two disorders. Myotonic discharges can also occur in other myopathies (including sIBM, vacuolar myopathies, or myofibrillar myopathies), 116,117 and are frequently found in paraspinal muscles in Pompe disease 118 . Last, concurrent motor neuron disease would point to VCP ‐myopathy, whereas a neuropathy may be observed in sIBM, 119 sarcoidosis, or amyloidosis.…”

Section: Electrodiagnostic Findingsmentioning

confidence: 99%

Myopathies with finger flexor weakness: Not only inclusion‐body myositis

2020

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Muscle disorders are characterized by differential involvement of various muscle groups. Among these, weakness predominantly affecting finger flexors is an uncommon pattern, most frequently found in sporadic inclusion-body myositis. This finding is particularly significant when the full range of histopathological findings of inclusion-body myositis is not found on muscle biopsy. Prominent finger flexor weakness, however, is also observed in other myopathies. It occurs commonly in myotonic dystrophy types 1 and 2. In addition, individual reports and small case series have documented finger flexor weakness in sarcoid and amyloid myopathy, and in inherited myopathies caused by ACTA1, CRYAB, DMD, DYSF, FLNC, GAA, GNE, HNRNPDL, LAMA2, MYH7, and VCP mutations. Therefore, the finding of finger flexor weakness requires consideration of clinical, myopathological, genetic, electrodiagnostic, and sometimes muscle imaging findings to establish a diagnosis. K E Y W O R D S distal myopathy, finger flexor weakness, inclusion-body myositis, myopathy with rimmed vacuoles, myotonic dystrophy 2 | SPORADIC INCLUSION-BODY MYOSITIS sIBM is the most common acquired myopathy after 50 years of age. 3 Its pattern of upper limb muscle involvement has been extensively characterized by both clinical examination and imaging, 4-11 and primarily involves finger flexor muscles. The flexor digitorum profundus (FDP) and flexor pollicis longus are most frequently and most severely affected (Figure 1A,B), with weakness demonstrated in approximately 90% of sIBM patients. 5-7 Within the FDP itself, different fingers can be involved to different degrees. 12 The FDP inserts onto the distal

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Clinical and Electrophysiological Findings in Hereditary Inclusion Body Myopathy Compared With Sporadic Inclusion Body Myositis

Abstract: sIBM and hIBM seem to have similar electromyographic changes. The combination of clinical, serological, and histopathological findings can guide genetic testing to the final diagnosis.

Cited by 13 publications

References 36 publications

Myofibrillar Myopathy Mimicking Polyneuropathy

Myofibrillar Myopathy Mimicking Polyneuropathy

Clinical Reasoning: A 40-year-old woman presenting with distal leg weakness

Myopathies with finger flexor weakness: Not only inclusion‐body myositis

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