Selective atrophy of the abductor digiti quinti: an MRI study.
OBJECTIVE
Entrapment of the first branch of the lateral plantar nerve is a well-recognized but diagnostically elusive cause of heel pain. The MR finding of selective atrophy of the abductor digiti quinti (ADQ) muscle has been reported as a marker of such entrapment. We performed a prospective study of consecutive patients undergoing foot and ankle MRI to determine the prevalence of ADQ atrophy and to examine the clinical symptoms of patients found to have ADQ atrophy.


METHODS
A prospective study of all patients referred for ankle and foot MRI examinations was performed. Six hundred two patients were included in the study: 387 females and 215 males. All images were evaluated for the presence of selective fatty atrophy of the ADQ muscle. The clinical notes on all patients with findings of ADQ atrophy were analyzed for descriptions of symptoms leading to the MR examination, the presence of symptoms that might be related to nerve entrapment, and the influence on clinical management related to the MR finding of ADQ atrophy.


RESULTS
Thirty-eight of the 602 patients had selective fatty atrophy of the ADQ, 29 females and nine males. Only one patient had a clinical diagnosis of possible nerve entrapment before MR examination. MRI findings of ADQ atrophy altered clinical management in only one patient.


CONCLUSIONS
Selective fatty atrophy of the ADQ is not a rare finding on MR examination of the foot and ankle, being seen in 6.3% of all studies and in 7.5% of all studies in females. The clinical relevance of selective ADQ atrophy seen on MRI is uncertain.
Recht
Michael P
MP
Division of Radiology, A-21, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA. rechtm@ccf.org
Grooff
Paul
P
Ilaslan
Hakan
H
Recht
Hannah S
HS
Sferra
James
J
Donley
Brian G
BG
D000328:Adult; D000368:Aged; D005260:Female; D005534:Foot Diseases / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D009133:Muscular Atrophy / Q000175:diagnosis* / Q000209:etiology; D009408:Nerve Compression Syndromes / Q000150:complications / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity