Imaging Studies

Magnetic resonance imaging (MRI) using the short inversion imaging recovery (STIR) technique displays high signal intensity in the affected nerve segment at the site of compression, probably due to edema in myelin sheath and perineurium. Magnetic resonance neurography is evolving as an important tool in sorting out various painful limb syndromes involving forearm and shoulder. This technique has been incorporated by some groups into treatment of patients with routine entrapment syndromes (eg, carpal and cubital tunnel syndrome). MRI and other imaging modalities are used with atypical presentations of common disorders or with recurrent symptoms after previous operation, as well as with suspected rare entrapment. For example, MRI is especially helpful in identifying a mass lesion in patients with a lesion compressing the suprascapular nerve, the ulnar nerve at the wrist, or the posterior interosseous nerve (PIN).

Diagnostic Procedures

The diagnosis of most entrapment neuropathies can usually be established on clinical grounds alone. For typical cases of carpal tunnel and ulnar cubital syndromes, electrodiagnostic tests (nerve conduction study and electromyography) are not always necessary. Still, they provide useful information: confirming the clinical diagnosis and localization, grading the lesion, identifying an underlying or superimposed peripheral neuropathy, and distinguishing other entities. Additionally, a baseline electrodiagnostic study may allow comparison with a postoperative study in patients with persistent symptoms.

In more unusual entrapment neuropathies such as those involving the suprascapular nerve, the ulnar nerve at the wrist, or the posterior interosseous nerve (PIN), electrodiagnostic tests may be invaluable. For PIN syndrome, electrodiagnostic studies combined with neuromuscular ultrasound can guide accurate electrode localization and can provide diagnostic information about lesion location.^{[27, 28]}

Local nerve block with a local anesthetic agent is useful in confirming the diagnosis of certain entrapments such as meralgia paresthetica.

Treatment & Management

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Media Gallery

Chest PA radiograph showing a right cervical rib (arrows), a possible cause of thoracic outlet syndrome.
Ulnar nerve (U) transposition at the elbow. A: The medial intermuscular septum (arrows) is resected to prevent compression of the transposed nerve. Vasoloops are around the ulnar nerve and a vascular pedicle between the nerve and the septum that has been preserved. B: After subcutaneous transposition, the ulnar nerve is observed lax in elbow flexion. The ulnar nerve and its distal branches are surrounded by vasoloops.
Common peroneal nerve decompression at the fibular neck. A: The common peroneal nerve (P) has been identified and mobilized proximal to the fibular tunnel region, fascia (F) covering peroneus longus. B: The common peroneal nerve has been traced through the fibular tunnel. The fascia overlying the peroneus longus muscle has been divided and the muscle (M) has been retracted. The fascial band overlying the nerve is released.
Median nerve (M) after decompression at the wrist; note the congestion from the longstanding compression. The transverse carpal ligament (arrows) has been transected. Fat is observed distally.

of 4

Author

Amgad Saddik Hanna, MD Assistant Professor, Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health

Amgad Saddik Hanna, MD is a member of the following medical societies: American Association of Neurological Surgeons, Central Neuropsychiatric Association, Congress of Neurological Surgeons

Disclosure: Nothing to disclose.

Coauthor(s)

Tristan Blase Fried, MD Resident Physician, Department of Orthopedic Surgery, Thomas Jefferson Hospital

Disclosure: Nothing to disclose.

George M Ghobrial, MD Resident Physician, Department of Neurological Surgery, Thomas Jefferson University Hospital

Disclosure: Nothing to disclose.

James S Harrop, MD Associate Professor, Departments of Neurological and Orthopedic Surgery, Jefferson Medical College of Thomas Jefferson University

James S Harrop, MD is a member of the following medical societies: American Association of Neurological Surgeons, American College of Surgeons, American Spinal Injury Association, Cervical Spine Research Society, Congress of Neurological Surgeons, North American Spine Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Depuy spine consulant, Asterias, Bioventus, Tejin serve on advisory boards<br/>Received research grant from: DOD, PICORI<br/>Received income in an amount equal to or greater than $250 from: Stryker honorarium.

Robert J Spinner, MD The Burton M Onofrio, MD, Professor of Neurosurgery, Professor of Orthopedics and Anatomy, Mayo Medical School; Co-Director, Brachial Plexus Clinic, Consultant, Department of Neurologic Surgery, Mayo Clinic

Robert J Spinner, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association for Hand Surgery, American Association for the Advancement of Science, American Association of Clinical Anatomists, American Association of Neurological Surgeons, American College of Surgeons, American Medical Association, American Orthopaedic Association, Congress of Neurological Surgeons

Disclosure: Royalties for: Mayo Medical Ventures.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Ryszard M Pluta, MD, PhD (Retired) Associate Professor, Neurosurgical Department Medical Research Center, Polish Academy of Sciences, Poland; (Retired) Clinical Staff Scientist, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health (NIH); (Retired) Fishbein Fellow, JAMA

Ryszard M Pluta, MD, PhD is a member of the following medical societies: Congress of Neurological Surgeons, Polish Society of Neurosurgeons

Disclosure: Nothing to disclose.

Chief Editor

Brian H Kopell, MD Associate Professor, Department of Neurosurgery, Icahn School of Medicine at Mount Sinai

Brian H Kopell, MD is a member of the following medical societies: Alpha Omega Alpha, American Association of Neurological Surgeons, American Society for Stereotactic and Functional Neurosurgery, Congress of Neurological Surgeons, International Parkinson and Movement Disorder Society, North American Neuromodulation Society

Disclosure: Received consulting fee from Medtronic for consulting; Received consulting fee from Abbott Neuromodulation for consulting; Received Consulting Fee from ClearPoint Neuro.

Additional Contributors

Michael G Nosko, MD, PhD Associate Professor of Surgery, Chief, Division of Neurosurgery, Medical Director, Neuroscience Unit, Medical Director, Neurosurgical Intensive Care Unit, Director, Neurovascular Surgery, Rutgers Robert Wood Johnson Medical School

Michael G Nosko, MD, PhD is a member of the following medical societies: Academy of Medicine of New Jersey, Congress of Neurological Surgeons, Canadian Neurological Sciences Federation, Alpha Omega Alpha, American Association of Neurological Surgeons, American College of Surgeons, American Heart Association, American Medical Association, New York Academy of Sciences, Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Acknowledgements

Dachling Pang, MD, FRCS(C), FACS Professor of Pediatric Neurosurgery, University of California, Davis, School of Medicine; Chief, Regional Center for Pediatric Neurosurgery, Kaiser Permanente Hospitals of Northern California

Dachling Pang, MD, FRCS(C), FACS is a member of the following medical societies: Alpha Omega Alpha, American Association of Neurological Surgeons, American College of Surgeons, Congress of Neurological Surgeons, Ontario Medical Association, and Royal College of Physicians and Surgeons of Canada

Disclosure: Nothing to disclose.

Kamran Sahrakar, MD, FACS Clinical Professor, Department of Neurosurgery, University of California at San Francisco

Kamran Sahrakar, MD, FACS is a member of the following medical societies: Alpha Omega Alpha, American Association of Neurological Surgeons, American Medical Association, California Medical Association, Florida Medical Association, and Nevada State Medical Association

Disclosure: Nothing to disclose.