Evidence map›Paper›PMID 41441220›Full record

ArticleNeurology international2025

Thenar Muscle Atrophy: Clinical, Electrodiagnostic, and Ultrasound Features in 197 Patients.

Lisa B E Shields, Vasudeva G Iyer, Stephen Furmanek, Yi Ping Zhang, Christopher B Shields

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Article in Neurology international, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

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1citing papers in PubMed
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1 · What the graph read from it

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2 · The registry

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3 · Its place in the literature

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1 citing paper in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

5 authors.

Lisa B E ShieldsNorton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, USA.ORCID 0000-0002-1526-4063
Vasudeva G IyerNeurodiagnostic Center of Louisville, Louisville, KY 40245, USA.ORCID 0000-0002-7411-4575
Stephen FurmanekNorton Data Science Core, Norton Healthcare, Louisville, KY 40202, USA.ORCID 0000-0001-9112-2860
Yi Ping ZhangNorton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, USA.
Christopher B ShieldsNorton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, USA.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

BACKGROUND/

objectivesAtrophy of the thenar muscles (abductor pollicis brevis [APB], opponens pollicis [OP], and flexor pollicis brevis [FPB]) is most commonly caused by carpal tunnel syndrome (CTS). It may also occur following injury to the recurrent motor branch of the median nerve, proximal median nerve neuropathy, medial cord/lower trunk plexopathy, T1 radiculopathy, ventral horn cell disorder at C8 or T1, disuse atrophy, or congenital aplasia. Clinical observation of flattening of the thenar eminence coupled with electrodiagnostic (EDX) and ultrasound (US) studies is valuable in determining the etiology of thenar atrophy. This study describes clinical, EDX, and US findings in a large cohort of patients with thenar muscle atrophy.

methodsThis is a review of 197 patients (226 hands) with thenar atrophy who underwent EDX and US studies. Patients were divided into those with total thenar atrophy (all three thenar muscles were atrophic) or partial thenar atrophy (atrophy of one or two thenar muscles) based on clinical and US findings.

resultsOf the 226 hands, 174 (77.0%) had partial thenar atrophy, 217 (96.0%) had sensory loss, and all hands demonstrated weakness of the APB and OP muscles on examination. A total of 220 (97.3%) hands had EDX evidence of severe median nerve entrapment at the carpal tunnel. The compound muscle action potentials (CMAPs) of the APB muscle and sensory nerve action potentials (SNAPs) were absent in 186 (82.3%) and 212 (93.8%) hands, respectively. US study showed hyperechoic APB and OP muscles in 225 (99.6%) hands. The Heckmatt grade, determined by US, was 3 in 152 (67.3%) hands, showing increased muscle echogenicity with loss of architecture and reduced bone reflection.

conclusionsIn patients with thenar muscle atrophy, EDX studies were not always conclusive for confirming CTS due to an absence of SNAP and CMAP over the APB and second lumbrical muscles. In these cases, US is important to confirm the cause of thenar atrophy.

Indexed as

carpal tunnel syndromeelectrodiagnostic studymedian nerveneurologythenar muscle atrophyultrasound

Identifiers

PMID41441220
PMCPMC12736044

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