J Neurol Neurosurg Psychiatry 1999;66:245 ( February )
Neurological picture
Suprascapular nerve entrapment at the spinoglenoid notch
due to a ganglion cyst
A 46 year old man presented with dull
right shoulder pain irradiating to the right upper arm. Physical
examination showed right glenohumeral instability. There was no muscle
atrophy. Radiography and an echogram of the right shoulder were normal.
An EMG showed fibrillation potentials and positive sharp waves in the
right infraspinatus muscle; recruitment of motor units was reduced on maximal voluntary contraction. The right supraspinatus muscle was
normal. T1 weighted MRI of the right shoulder (figure A) disclosed an
ovoid low signal intensity mass (white arrowheads) at the spinoglenoid notch, impinging on the suprascapular artery and nerve (small black
arrows) between the supraspinatus (S) and infraspinatus (I) muscles.
(D=deltoid) On T2 weighted gradient echo image (figure B), the mass had
a homogeneous high signal intensity consistent with a paralabral
(ganglion) cyst. Coronal T1 weighted imaging (figure C) confirmed the
localisation of the mass (white and black arrowheads), astride the
scapular spine (white arrows), compressing the suprascapular nerve
(small black arrows).
Until recently, the diagnosis of suprascapular nerve
entrapment was only considered after development of marked weakness and
atrophy of the supraspinatus or infraspinatus muscles.1 MRI in patients with non-specific shoulder pain now makes earlier detection possible.2 Ganglion cysts account for most
lesions causing entrapment of the suprascapular nerve. Often, there is a history of weight lifting or of athletic shoulder activities. If
conservative treatment fails or if there is marked muscle atrophy, surgical decompression is recommended.3
MICHEL VAN ZANDIJCKE
Department of Neurology
JAN CASSELMAN
Department of Medical Imaging, Algemeen Ziekenhuis
St-Jan, Brugge, Belgium
Correspondence to: Dr Michel Van Zandijcke, Department
of Neurology, AZ St-Jan, Ruddershove 10, B-8000 Brugge, Belgium.
Telephone 0032 50 452370; fax 0032 50 452359
References
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Liveson JA,
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J Neurol Neurosurg Psychiatry
1991;54:241-243[Abstract].
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Fritz RC,
Helms CA,
Steinbach LS,
et al. Suprascapular nerve entrapment: evaluation with MR imaging.
Radiology
1992;182:437-444[Abstract/Free Full Text].
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Antoniadis G,
Richter HP,
Rath S,
et al. Suprascapular nerve entrapment: experience with 28 cases.
J Neurosurg
1996;85:1020-1025[Medline].
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© 1999 by Journal of Neurology, Neurosurgery, and Psychiatry
