Focal myositis – A neurogenic phenomenon?

Lunde, Hanne Marie Bøe; Skeie, Geir; Bertelsen, Anne K.; Karlsen, Bjørn; Miletić, Hrvoje; Lindal, Sigurd; Brautaset, N. J.; Bindoff, Laurence A.

doi:10.1016/j.nmd.2011.10.023

Cited by 18 publications

(13 citation statements)

References 13 publications

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“…Ainsi, l'existence d'un syndrome myogène focal avec des potentiels d'unités motrice polyphasiques, microvoltés et surtout de durée brève, associés à la normalité des tracés à distance est un argument fort pour le diagnostic [7]. L'étude de la conduction nerveuse peut parfois montrer des anomalies suggérant des phénomènes chroniques de dénervation dans le territoire musculaire atteint par la myosite focale [21]. Cette observation a suggéré à certains auteurs des hypothèses quant aux mécanismes physiopathologiques impliqués (cf.…”

Section: L'électromyographieunclassified

Myosite focale : une maladie méconnue

Gallay

Streichenberger

Benveniste

et al. 2017

La Revue de Médecine Interne

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Focal myositis are inflammatory muscle diseases of unknown origin. At the opposite from the other idiopathic inflammatory myopathies, they are restricted to a single muscle or to a muscle group. They are not associated with extramuscular manifestations, and they have a good prognosis without any treatment. They are characterized by a localized swelling affecting mostly lower limbs. The pseudo-tumor can be painful, but is not associated with a muscle weakness. Creatine kinase level is normal. Muscle MRI shows an inflammation restricted to a muscle or a muscle group. Muscle biopsy and pathological analysis remain necessary for the diagnosis, showing inflammatory infiltrates composed by macrophages and lymphocytes without any specific distribution within the muscle. Focal overexpression of HLA-1 by the muscle fibers is frequently observed. The muscle biopsy permits to rule out differential diagnosis such a malignancy (sarcoma). Spontaneous remission occurs within weeks or months after the first symptoms, relapse is unusual.

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Section: L'électromyographieunclassified

Myosite focale : une maladie méconnue

Gallay

Streichenberger

Benveniste

et al. 2017

La Revue de Médecine Interne

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“…In most calf NMH cases, increased CK plasma levels and focal inflammation likely represent a reactive response to degeneration remodeling of denervated fibers [5]. Correspondingly, MHC-I upregulation and T-cell deposits were extremely limited in our patient's gastrocnemius muscle, in contrast to the usual pattern of myositides.…”

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confidence: 60%

“…Sir, -Neurogenic focal muscle hypertrophy (NMH) is a rare event in different instances of impaired nerve conduction: acquired and inherited polyneuropathies/multineuropathies [1,2], post-polio syndromes [3], spinal stenosis, spinal muscle atrophies, radiculopathies [4]. Unilateral calf hypertrophy is an uncommon, but not unique, finding in S1 radiculopathy [5]. Muscle histology shows denervation, with atrophic as well as hypertrophic fibers, and frequent coexistence of inflammatory changes.…”

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confidence: 99%

“…Steroid treatment was carried out with prednisone 50 mg/day for 3 weeks, with no clinical remission. Consequently, the patient was submitted to CT-guided percutaneous transforaminal periganglionic, and trans-articular zygapophyseal infiltration of the right L5-S1 root with a mix of local anesthetic (Ropivacain, 2 mg) and corticosteroid (Triamcinolon, 40 mg), with considerable clinical remission: shortly after the proce- Coexisting inflammatory changes have led to inclusion of NMH into the domain of focal myositis (FM) [5,6], a benign pseudotumor lesion within a single skeletal muscle, predominant at the lower limbs, possibly recurrent or evolving into diffuse myositis [7]. Unlike the present case, histology of pure FM usually shows no neurogenic changes and a prominent inflammation [8,9].…”

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confidence: 99%

“…In most radiculopathy-associated NMH cases, CRDs, generated by denervated fibers, are likely to act as hypertrophying agents, in analogy with increased muscle mass and fiber diameters obtained by functional muscle electrical stimulation, both experimentally [10] and in conus/cauda syndrome patients [11]. Nonetheless, NMH reports in absence of CRDs [5,12] suggest coexisting pathomechanisms, such as compensatory overload; accordingly, in our case, a minority of hypertrophied "non-target" fibers, thus possibly not denervated, were detected.…”

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confidence: 99%

See 2 more Smart Citations

Calf muscle hypertrophy following S1 radiculopathy: A stress disorder caused by hyperactivity with variable response to treatmen

Volpi¹,

Ginanneschi²,

Cerase³

et al. 2018

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Muscle hypertrophy following acquired neurogenic injury: systematic review and analysis of existing literature

Strano,

Bosco,

Laurini

et al. 2024

Ann Clin Transl Neurol

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ObjectivesNeurogenic muscle hypertrophy (NMH) is a rare condition characterized by focal muscle hypertrophy caused by chronic partial nervous injury. Given its infrequency, underlying mechanisms remain poorly understood. Inspired by two clinical cases, we conducted a systematic review to gain insights into the different aspects of NMH.MethodsWe systematically searched online databases up until May 30, 2023, for reports of muscle hypertrophy attributed to acquired neurogenic factors. We conducted an exploratory analysis to identify commonly associated features. We also report two representative clinical cases.ResultsOur search identified 63 reports, describing 93 NMH cases, to which we added our two cases. NMH predominantly affects patients with compressive radiculopathy (68.4%), negligible muscular weakness (93.3%), and a chronic increase in muscle bulk. A striking finding in most neurophysiological studies (60.0%) is profuse spontaneous discharges, often hindering the analysis of voluntary traces. Some patients exhibited features consistent with more significant muscle damage, including higher creatine phosphokinase levels, muscle pain, and inflammatory muscle infiltration. These patients are sometimes referred to in literature as “focal myositis.” Treatment encompassed corticosteroid, Botulinum Toxin A, decompressive surgery, antiepileptic medications, and nerve blocks, demonstrating varying degrees of efficacy. Botulinum Toxin A yielded the most favorable response in terms of reducing spontaneous discharges.InterpretationThis systematic review aims to provide a clear description and categorization of this uncommon presentation of an often‐overlooked neurological disorder. Though questions remain about the underlying mechanism, evidence suggests that aberrant fiber overstimulation along with increased workload that promotes focal damage may result in muscle hypertrophy. This may serve as a guide for therapeutic interventions.

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Focal myositis – A neurogenic phenomenon?

Cited by 18 publications

References 13 publications

Myosite focale : une maladie méconnue

Myosite focale : une maladie méconnue

Calf muscle hypertrophy following S1 radiculopathy: A stress disorder caused by hyperactivity with variable response to treatmen

Muscle hypertrophy following acquired neurogenic injury: systematic review and analysis of existing literature

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