Isolated musculocutaneous neuropathy caused by a proximal humeral exostosis

Axillary and musculocutaneous neuropathies

This chapter covers axillary and musculocutaneous neuropathies, with a focus on clinically relevant anatomy, electrodiagnostic approaches, etiologic considerations, and management principles. Disorders of the lateral antebrachial cutaneous nerve, a derivative of the musculocutaneous nerve, are also reviewed. We emphasize the importance of objective findings, including the physical examination and electrodiagnostic evaluation in confirming the isolated involvement of each nerve which, along with the clinical history, informs etiologic considerations. Axillary and musculocutaneous neuropathies are both rare in isolation and most frequently occur in the setting of trauma. Less commonly encountered etiologies include external compression or entrapment, neoplastic involvement, or immune-mediated disorders including neuralgic amyotrophy, postsurgical inflammatory neuropathy, multifocal motor neuropathy, vasculitic neuropathy, and multifocal chronic inflammatory demyelinating polyradiculoneuropathy.

Electrodiagnostic Assessment of Uncommon Mononeuropathies

Carpal tunnel syndrome, ulnar neuropathy at the elbow, and peroneal neuropathy are the most common mononeuropathies; however, other individual nerves may also be injured by various processes. These uncommon mononeuropathies may be less readily diagnosed owing to unfamiliarity with the presentations and vague symptoms. Electrodiagnostic studies are essential in the evaluation of uncommon mononeuropathies and can assist in localization and prognostication. However, they can also be challenging; stimulation at the proximal sites is difficult and well-validated reference values are not available. This article reviews the electrodiagnostic assessment of several uncommon upper and lower extremities mononeuropathies.

Isolated Musculocutaneous Neuropathy Secondary to an Immune-Mediated Brachial Plexopathy: A Case Report of a Rare Phenotype With a Side Note on Patterns of Weakness and an Update on Nerve Pathology

We describe a 50-year-old man who developed a low-frequency pattern of weakness, musculocutaneous neuropathy, with weakness of the biceps, coracobrachialis and brachialis in an immune-mediated brachial plexopathy. The aim of this article is to highlight both the low- and high-frequency patterns of weakness of the immune-mediated brachial plexopathies, and we focus on the patterns of recognition. We then segue into the pathology of the immune-mediated plexopathies and highlight the recent spectacular magnetic resonance imaging studies that demonstrate hourglass constrictions of peripheral nerves outside of the brachial plexus in afflicted patients. This opens up a window for the exciting possibility of neurolysis of constricted nerves in patients who have not responded adequately to immunotherapy.

Rare communication between the musculocutaneous and median nerves in the forearm: its clinical significance

Morphologic classifications of communication between musculocutaneous and median nerves are not based on the distribution and the function of the communicating branch. The authors report a rare case of such a communication with passage of the median nerve through the pronator teres muscle and discuss its clinical significance. The musculocutaneous nerve was divided into a lateral branch that continued to the lateral antebrachial cutaneous nerve and a medial branch that joined the median nerve in the forearm. The authors separated the nerve bundles and noted that the communicating branch derived from the sixth to seventh cervical nerves and supplied nerve fibers to the pronator teres muscle and the proper palmar digital nerve of the thumb. In addition, the median nerve penetrated the humeral head of the pronator teres muscle. Isolated musculocutaneous neuropathy with such a communication may cause unexpected symptoms such as sensory deficit in the palm and muscular weakness of the forearm and the thumb.

Peripheral nerve injuries due to osteochondromas: analysis of 20 cases and review of the literature

Object

Nerve compressions due to osteochondromas are extremely rare. The aim of this retrospective study was to investigate the mechanisms, diagnostic evaluations, and treatment of nerve lesions due to osteochondromas, and to review the literature.

Methods

The authors retrospectively reviewed their clinic data archive from 1998 through 2008, and 20 patients who were operated on due to peripheral nerve injuries caused by osseous growth were enrolled in the study. Patients' age, duration of symptoms, localizations, intraoperative findings, and modified British Medical Research Council (MRC) and electromyography data obtained from hospital records were evaluated. The literature on this topic available in PubMed was also reviewed. All 20 patients underwent surgery, which consisted of tumor excision performed by orthopedic surgeons and nerve decompression performed by neurosurgeons.

Results

There were 17 men and 3 women included in the study, with a mean age of 21 years (range 18–25 years). Three patients had multiple hereditary exostoses, and 17 had a solitary exostosis. All of the patients underwent en bloc resection. The most common lesion site was the distal femur (45%). The peroneal and posterior tibial nerves were the structures that were affected the most frequently. The mean follow-up was 3.9 years (range 2–7 years). After the surgery, all patients (100%) experienced good sensory recovery (modified MRC Grade S4 or S5).

Conclusions

To the authors' knowledge, no large series have reported peripheral nerve compression due to exostoses. The authors have several recommendations as a result of their findings. First, all patients with peripheral nerve compression due to an osteochondroma should undergo surgery. Second, preoperative electromyographic examinations and radiographic evaluation, consisting of MRI and CT to provide optimal information about the lesion, are crucially important. Third, immediate treatment is mandatory to regain the best possible recovery. And fourth, performing nerve decompression first and en bloc resection of osteochondroma consecutively in a multidisciplinary fashion is strongly recommended to avoid peripheral nerve injury.

Compression and entrapment neuropathies

Peripheral nerve entrapments are frequent. They usually appear in anatomical tunnels such as the carpal tunnel. Nerve compressions may be due to external pressure such as the fibular nerve at the fibular head. Malignant or benign tumors may also damage the nerve. For each nerve from the upper and lower limbs, detailed clinical, electrophysiological, imaging, and therapeutic aspects are described. In the upper limbs, carpal tunnel syndrome and ulnar neuropathy at the elbow are the most frequent manifestations; the radial nerve is less frequently involved. Other nerves may occasionally be damaged and these are described also. In the lower limbs, the fibular nerve is most frequently involved, usually at the fibular head by external compression. Other nerves may also be involved and are therefore described. The clinical and electrophysiological examination are very important for the diagnosis, but imaging is also of great use. Treatments available for each nerve disease are discussed.

Double innervation of the brachialis muscle: anatomic-physiological study

INTRODUCTION

Double innervation of the brachialis muscle has been previously reported in anatomical studies. This study aims to investigate the frequency and clinical significance of double innervation of brachialis by anatomical and electromyographic techniques.

MATERIALS AND METHODS

(1) The existence, origin and pattern of distribution of a branch from the radial nerve to brachialis were dissected on 20 cadaveric arms. (2) Nerve conduction studies (NCS) of 100 patients were performed. The radial nerve was stimulated, registering muscle potentials (MP) in the brachialis muscle. Subsequently, another MP was obtained by Erb's stimulation, corresponding to the whole brachialis innervation. The relative percentage of innervation from the radial nerve was calculated. (3) Two patients with lesions of the lateral cord of the brachial plexus and preserved elbow flexion were submitted to NCS.

RESULTS

Double innervation was found in 65 % of the anatomical preparations, following different patterns of distribution. In the NCS, 90% of the patients showed MP in the brachialis muscle after stimulating the radial nerve. The mean percentage of relative innervation was 11 %. Two patients with lesions of the lateral cord showed an important contribution from the radial nerve.

CONCLUSIONS

Variations in the relative percentage of innervation from the radial nerve could be due to the different sizes and shapes of this branch. The functional significance of this branch can become crucial if the main innervation to the brachialis muscle fails. When planning surgical antero-external approach to the humerus, it should be kept in mind and preserved.

Musculocutaneous neuropathy: case report and discussion

The musculocutaneous nerve arises from the lateral cord of the brachial plexus and contains fibers from the C5, C6, and C7 spinal nerve roots. It innervates such muscles as the biceps brachii and brachialis as well as supply branches to the skin over the lateral cubital and forearm regions via the lateral antebrachial cutaneous nerve. Musculocutaneous neuropathy can arise from exercise, participating in sports, strenuous activity, cast placement, trauma, and surgery in addition to other less understood causes such as Parsonage Turner syndrome. We present the case of a 55-year-old female who complained of numbness, weakness, and pain throughout the arm starting 1 day following a surgical procedure. Electrodiagnostic testing revealed a musculocutaneous neuropathy with significant axonal injury. Symptoms of musculocutaneous neuropathy may be similar to cervical spinal nerve root impingement or brachial plexus lesions. Therefore, magnetic resonance imaging and electrodiagnostic studies may be useful in differentiating between these conditions. Once the diagnosis of musculocutaneous neuropathy has been made, treatments include relative rest, nonsteroidal anti-inflammatory drugs, splinting, physical therapy, and surgical decompression in cases that do not respond to conservative management.

Traumatic musculocutaneous neuropathy: a case report

Isolated injury of the musculocutaneous nerve is a rare disorder. Reported cases are claimed to present with loss of biceps and brachialis power without a disturbing pain. The injury generally occurs after strenuous exercise and could be demonstrated by electrophysiological examination. We report a case of musculocutaneous nerve injury which occurred after a vigorous push and which presented with unusual symptoms and findings. The patient complained of episodic severe pain attacks which started from the axilla and radiated over the musculocutaneous nerve distribution including the lateral antebrachial cutaneous nerve area. He did not respond to 3 months of conservative treatment including multiple corticosteroid injections and finally required surgical release. Surgical epineurotomy resulted in immediate relief. This is the first reported case of acute musculocutaneous nerve injury presenting with unusual symptoms and findings. The operative release procedure performed was also not required in any of the other reported cases. An excellent result was obtained with epineurotomy.

Tibial osteochondroma causing foot pain mimicking tarsal tunnel syndrome: a case report

Nerve entrapment syndromes of the lower extremity are relatively rare in patients with multiple hereditary osteochondromatosis. A case of tarsal tunnel like symptoms in a 52-year-old woman with a distal tibial osteochondroma is presented. This case emphasizes that the possibility of nerve compression needs to be considered in a patient with multiple hereditary osteochondromatosis and that tibial osteochondromas can be a cause of tarsal tunnel-like symptoms.

A series of 146 peripheral non—neural sheath nerve tumors: 30-year experience at Louisiana State University Health Sciences Center

Object. This is a retrospective review of 146 surgically treated benign and malignant peripheral non—neural sheath tumors (PNNSTs). Tumor classifications with patient numbers, locations of benign PNNSTs, and surgical techniques and adjunctive treatments are presented. The results of a literature review regarding tumor frequencies are presented.

Methods. One hundred forty-six patients with 111 benign and 35 malignant PNNSTs were treated between 1969 and 1999 at the Louisiana State University Health Sciences Center (LSUHSC). The benign tumors included 33 ganglion cysts, 16 cases of localized hypertrophic neuropathy, 12 lipomas, 12 tumors of vascular origin, and 11 desmoid tumors. There were four each of lipofibrohamartomas, myositis ossificans, osteochondromas, and ganglioneuromas; two each of meningiomas, cystic hygromas, myoblastoma or granular cell tumors, triton tumors, and lymphangiomas; and one epidermoid cyst. The locations of benign PNNSTs were the following: 33 in the brachial plexus region, 39 in an upper extremity, one in the pelvic plexus, and 38 in a lower extremity.

The malignant PNNSTs included 35 surgically treated carcinomas, 15 of which originated in the breast and nine in the lung. There were two melanomas metastatic to nerve and one tumor each that had metastasized from the bladder, rectum, skin, head and neck, and thyroid, and from a primary Ewing sarcoma. There was a single lymphoma that had metastasized to the radial nerve and one chordoma and one osteosarcoma, each of which had metastasized to the brachial plexus.

Conclusions. There were more benign PNNSTs than malignant ones. Benign tumors were relatively equally distributed in the brachial plexus region and upper and lower extremities, with the exception of the pelvic plexus, which had only one tumor.