Diagnosing neurogenic thoracic outlet syndrome with the triple stimulation technique

Use of Electroneuromyography in the Diagnosis of Neurogenic Thoracic Outlet Syndrome: A Systematic Review and Meta-Analysis

Neurogenic thoracic outlet syndrome (NTOS) is a disabling condition. Its diagnosis remains challenging and is mainly guided by examination. Yet, electrophysiological evaluations are the gold standard for diagnosis of entrapment syndromes. We aimed to assess the interest of electrophysiological evaluation to diagnose NTOS. A systematic literature research was performed using PubMed, ScienceDirect, Embase, Cochrane and Google Scholar databases to collect studies reporting results of electrophysiological assessment of patients with NTOS. Then, a meta-analysis was conducted. Nine studies were eligible and concerned two hundred and thirteen patients. Results were heterogenous among studies and the quality of evidence was very low to moderate. Data could not evaluate sensitivity or specificity of electrophysiological evaluations for NTOS. The meta-analysis found significantly decreased amplitudes of medial antebrachial cutaneous nerve SNAP (sensory nerve action potential), ulnar SNAP, median CMAP (compound motor action potential) and ulnar CMAP. Needle examination found abnormalities for the abductor pollicis brevis, first dorsal interosseous and adductor digiti minimi. Unlike most upper-limb entrapment syndromes, nerve conduction assessment only provided clues in favour of NTOS. Decreased amplitude for ulnar SNAP, medial antebrachial cutaneous SNAP, median CMAP and ulnar CMAP should be assessed, as well as needle examination. Larger studies are needed to evaluate the sensitivity and specificity of electrophysiology in NTOS diagnosis.

Surgical Anatomy of the Posterior Intermuscular Approach to the Brachial Plexus

Background: First rib resection and scalenectomy is a well-established treatment option for thoracic outlet syndrome. The posterior approach is rarely used due to extensive muscle sacrifice resulting in significant procedural morbidity. In this paper, we report the surgical anatomy of modified and less-invasive muscle-sparing posterior approach. Methods: Eleven human cadavers were used in this study. With specific care to preserve muscles' integrity, the brachial plexus was exposed by dissecting through the posterior neck musculature. A muscular triangle was found under the trapezius muscle, which provided direct access to deeper structures. Four anatomical reference points were identified to denote a 3-dimensional space enclosing proximal brachial plexus. Results: A muscular triangle was found under the trapezius muscle in all cadavers. It was bordered infero-medially by rhomboid minor, supero-medially by splenius capitis, and laterally by levator scapula muscles. The inferomedial border (rhomboid) was 55 mm (48-80), superomedial border (splenius capitis) was 60.5 mm (42-89), and the lateral border (levator scapulae) was 99 mm (60-130). A consistent vein was present inside the triangle and could be used as an anatomical landmark. The 4 reference points were C5, T1 intervertebral foramina, transverse tubercle, and scalene tubercle of the first rib. Removal of the first rib could be performed without brachial plexus retraction. The latter was exposed from neural foramina to lateral border of the first rib. Conclusions: The posterior approach provides ample space to for exposure and manipulation with the first rib and proximal brachial plexus.

Thoracic outlet syndrome in a postoperative cervical spondylotic myelopathy patient: A case report

RATIONALE

Thoracic outlet syndrome (TOS) is a rare disease that presents with neurogenic and vascular symptoms similar to those of cervical spondylosis. However, making the diagnosis of TOS can be challenging due to a lack of standardized objective confirmatory tests.

PATIENT CONCERNS

A 66-year-old man presented with neck, supraclavicular, and right shoulder pain as well as numbness and weakness in the right arm after surgery to correct cervical spondylotic myelopathy (CSM).

DIAGNOSIS

Magnetic resonance imaging confirmed the diagnosis of CSM. He was diagnosed with TOS based on the manifestations and examination findings.

INTERVENTIONS

After surgery for CSM, nonoperative management was provided.

OUTCOMES

The patient reported pain relief and improving sensation in the shoulder and supraclavicular region.

LESSONS

Based on this case and the reviewed literature, to optimize the diagnosis and treatment of CSM, clinicians should consider preoperative differential diagnosis to preliminarily exclude it.

Diagnosing chronic inflammatory demyelinating polyradiculoneuropathy with triple stimulation technique

OBJECTIVE

To assess the value of triple stimulation technique (TST) for diagnose of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

METHODS

Seven clinically suspected CIDP patients who did not fulfill EFNS/PNS electrodiagnostic criteria for demyelinating neuropathy were enrolled in our study. Routine nerve conduction studies, lumbar puncture, spinal cord magnetic resonance imaging and TST were detected. The patients were being treated with oral prednisone starting at 1 mg/kg daily. The overall disability sum score was performed to evaluate the effect of corticosteroids.

RESULTS

Twenty-eight motor nerves were tested with TST, two conduction blocks (CBs) were detected between the root emergence and the Erb point in six patients respectively and one CB was detected in one patient. Symptoms of all seven patients improved after treatment with oral prednisone.

CONCLUSION

TST can detect CBs located between the root emergence and the Erb point. TST is useful for early diagnosis of CIDP.

The positive effect of venlafaxine on central motor conduction

OBJECTIVES

Using the triple stimulation technique (TST) and conventional transcranial magnetic stimulation (TMS), this study was designed to investigate the effect of venlafaxine on central motor conduction in healthy adults.

PATIENTS AND METHODS

In this crossover, self-controlled trial, eight healthy adult volunteers were randomly divided into groups A and B. In group A, the volunteers were administered 1 venlafaxine capsule once daily for 7 consecutive days, followed by a 3-day break. Next, volunteers in this group received 1 placebo capsule once daily for 7 consecutive days. Group B received the treatments in the opposite order. The index finger tapping test, grip strength test, TST and conventional TMS examination for each hand were recorded before and one week after the administration of venlafaxine or placebo.

RESULTS

Compared to the placebo stage, in the venlafaxine stage, the number of index finger taps was significantly increased for both hands, and the TST amplitude and area ratios were significantly increased. The improvement in the TST amplitude ratio was significantly and positively correlated with the improvements in performance on the index finger tapping test.

CONCLUSION

Venlafaxine positively regulates central motor conduction in healthy adults.

The thoracic outlet syndromes: Part 1. Overview of the thoracic outlet syndromes and review of true neurogenic thoracic outlet syndrome

The thoracic outlet syndromes (TOSs) are a group of etiologically and clinically distinct disorders with 1 feature in common: compression of 1 or more neurovascular elements as they traverse the thoracic outlet. The medical literature reflects 5 TOSs: arterial; venous; traumatic neurovascular; true neurogenic; and disputed. Of these, the first 4 demonstrate all of the features expected of a syndrome, whereas disputed TOS does not, causing many experts to doubt its existence altogether. Thus, some categorize disputed TOS as a cervicoscapular pain syndrome rather than as a type of TOS. To better understand these disorders, their distinctions, and the reasoning underlying the categorical change of disputed TOS from a form of TOS to a cervicoscapular pain syndrome, a thorough understanding of the pertinent anatomy, pathology, pathophysiology, and the electrodiagnostic manifestations of their pathophysiologies is required. This review of the TOSs is provided in 2 parts. In this first part we address information pertinent to all 5 TOSs and reviews true neurogenic TOS. In part 2 we review the other 4 TOSs. Muscle Nerve 55: 782-793, 2017.