Drop finger caused by 8th cervical nerve root impairment: a clinical case series

[Finger drop variant of Guillain-Barré syndrome: a case report]

We report the case of a 31-year-old man with a finger drop variant of Guillain-Barré syndrome (GBS). The patient visited a neurological clinic with complaints of difficulty in extending the fingers, which occurred seven days after he had fever and diarrhea. The physician who first saw the patient suspected posterior interosseous nerve palsy and referred him to our hospital. Neurological examination 35 days after the onset revealed distal weakness of the upper extremities, particularly in the bilateral extensor digitorum (Medical Research Council [MRC] scale 1/1 [right/left]). The left triceps surae muscle was also weak (MRC scale 5/4). Bilateral Achilles tendon reflexes were absent, but other neurological findings were normal. Cerebrospinal fluid examination showed albuminocytologic dissociation. Serum immunoglobulin G antibodies against GM1 were positive. Nerve conduction studies revealed reduced amplitude of compound muscle action potentials (CMAPs) without evidence of demyelination in the median, ulnar, radial, and tibial nerves. CMAP amplitude was most severely reduced in the radial nerve among the upper extremity nerves. We diagnosed the patient with acute motor axonal neuropathy. His symptoms gradually improved after treatment with intravenous immunoglobulin. When encountering acute finger drop, neurologists should consider the finger drop variant of GBS as a differential diagnosis.

Detailed features and prognostic factors of twenty-three patients with drop finger caused by cervical radiculopathy: a retrospective multicentre study

PURPOSE

It has been reported that C7 and C8 nerve root impairment can cause drop finger; however, the clinical characteristics of each injured nerve root and post-operative outcomes remain unclear. This study aimed to investigate the detailed features and surgery-related prognostic factors of drop finger caused by cervical radiculopathy.

METHODS

We retrospectively investigated the clinical characteristics, paralysis patterns and surgery-related prognostic factors of 23 patients with drop finger caused by cervical radiculopathy who underwent posterior cervical foraminotomy. We classified paralysis into three patterns based on the fingers predominantly exhibiting extensor digitorum communis (EDC) muscle weakness: index finger side-dominant, middle and ring fingers-dominant and little finger side-dominant.

RESULTS

The aetiologies were cervical disc hernia (CDH) in ten patients, cervical spondylotic radiculopathy (CSR) in eight and both CDH and CSR in five. The levels of the decompressed root were C7 in one patient, C8 in 11 and both C7 and C8 in 11. Scapular pain was frequently observed as the initial symptom (78%), especially in patients with only C8 nerve root disorder (91%). Drop finger recovered to a score of ≥ 3 on manual muscle testing in 17 patients; patients with the little finger side-dominant pattern tended to have poor recoveries. Patients with CDH improved significantly than those with CSR or both CDH and CSR (p < 0.05).

CONCLUSIONS

Good surgical recovery of drop finger can be expected in patients with CDH and in those with index fingers-dominant and middle and ring fingers-dominant patterns.

The "Texas Longhorn" Syndrome: A Case of Posterior Interosseous Nerve Palsy With Noteworthy Observations

The posterior interosseous nerve (PIN) is quite a fascinating nerve. It wraps around the radial neck akin to the fibular nerve wrapping around the fibular neck. It can be compressed by the arcade of Frohse in a fashion similar to median nerve entrapment by the carpal tunnel. Furthermore, it divides into a number of branches, a simulacrum of the cauda equina, as it emerges from the supinator muscle. It is also associated with space-occupying pathologies; lipomas, and ganglion cysts being among the most common. It also has other interesting anatomical properties, such as fascicular compartmentalization, explaining PIN paralysis with radial nerve injuries. Finally, PIN lesions can lead to partial paralysis of finger extensors leading to the "Texas longhorn" hand gesture. We seize upon a case of PIN entrapment by fibrous adhesions and the arcade of Frohse, and explore the functional anatomy of the PIN.

Cervical spondylotic amyotrophy: a systematic review

PURPOSE

Cervical spondylotic amyotrophy (CSA) is characterized by upper limb muscle weakness and atrophy, without sensory deficits. The pathophysiology of CSA has been attributed to selective injury to the ventral nerve root and/or anterior horn of the spinal cord. This review aimed to delineate the history of CSA and to describe the epidemiology, etiology, pathophysiology, classification, clinical features, radiological and electrophysiological assessment, diagnosis, differential diagnosis, natural history and treatment of CSA.

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane library and Web of Science databases was conducted, from their inception to April 3, 2018.

RESULTS

Clinically, CSA is classified into three types: a proximal-type (involving the scapular muscles, deltoid and biceps), a distal-type (involving the triceps and muscles of the forearm and hand) and a diffuse-type (involving features of both the distal- and proximal-type). Diagnosis requires documentation of muscle atrophy, without significant sensory deficits, supported by careful neurological, radiological and neurophysiological assessments, with amyotrophic lateral sclerosis, Parsonage-Turner syndrome, rotator cuff tear and Hirayama disease being the principle differential diagnoses. Conservative management of CSA includes cervical traction, neck immobilization and physical therapy, with vitamin B12 or E administration being useful in some patients. Surgical treatment, including anterior decompression and fusion or laminoplasty, with or without foraminotomy, is indicated after conservative treatment failure. Factors associated with a poor outcome include the distal-type CSA, long symptom duration, older age and greater preoperative muscle weakness.

CONCLUSION

Although the disease process of CSA is self-limited, treatment remains challenging, leaving scope for future studies. These slides can be retrieved under Electronic Supplementary Material.