T2 Contributions to the Brachial Plexus

A meta-analysis on the anatomical variability of the brachial plexus: Part I - Roots, trunks, divisions and cords

INTRODUCTION

The brachial plexus is a complex anatomical structure that gives rise to all the nerves of the upper limb. Its variability is frequently observed and represents a challenge for interventions in the lower neck and axilla. The aim of this study was to present a comprehensive and evidence-based review with meta-analytic techniques on the variability of roots, trunks, divisions and cords of the brachial plexus.

MATERIALS AND METHODS

Major medical databases were searched to identify all anatomical studies investigating the variability in the formation of the brachial plexus. Data extracted consisted of demographic information, morphometric parameters, the arrangement of the brachial plexus at the level of the roots, trunks, divisions and cords and the relationship of the brachial plexus to the axillary artery and scalene muscles. The different configurations of the brachial plexus were put into a new classification, and the pooled prevalence of each case was calculated using a random effects model. A sub-analysis on age and geographical location was also performed.

RESULTS

A total of 40 studies (3055 upper limbs) were included in the meta-analysis. The regular arrangement of roots forming trunks was identified in 84% (95% CI 79-89%) of cases. The overall prevalence of the prefixed and postfixed brachial plexus was 11% (95% CI 6-17%) and 1% (95% CI 0-1%), respectively and in less than 0.1% of cases the brachial plexus received a branch from both C4 and T2. For divisions forming cords, the regular arrangement was observed in 96% (95% CI 93-98%) of cases. Additional communicating branches between the components of the brachial plexus appeared in 5% (95% CI 3-7%) of cases. The relationship of the brachial plexus to the axillary artery and scalene muscles was considered regular in 96% (95% CI 89-100%) and 86% (95% CI 66-98%) of cases, respectively. Analysis of the morphometric parameters revealed the proportional consistency between the components forming the plexus during aging.

CONCLUSIONS

Knowledge of anatomical variations of the brachial plexus is important for examinations and interventions in the lower neck and axilla. The variability was observed especially in the roots forming trunks, while divisions forming cords showed quite stable appearance. The results of this evidence-based review and meta-analysis can be applied in many different medical disciplines.

Motor function of the upper-extremity after transection of the second thoracic nerve root during total en bloc spondylectomy

BACKGROUND

In total en bloc spondylectomy (TES) of upper thoracic spine including the second thoracic (T2) vertebra, T2 nerve roots are usually transected. In this study, we examined the association between transection of the T2 nerve roots and upper-extremity motor function in patients with upper thoracic TES.

METHODS

We assessed 16 patients who underwent upper thoracic TES with bilateral transection of the T2 nerve roots. Patients were divided into three groups: 3 patients without any processing of T1 and upper nerve roots (T2 group), 7 with extensive dissection of T1 nerve roots (T1-2 group), and 6 with extensive dissection of T1 and upper nerve roots (C-T2 group). Postoperative upper-extremity motor function was compared between the groups.

RESULTS

Postoperative deterioration of upper-extremity motor function was observed in 9 of the 16 patients (56.3%). Three of the 7 patients in the T1-2 group and all 6 patients in the C-T2 group showed deterioration of upper-extremity motor function, but there was no deterioration in the T2 group. In the T1-2 group, 3 patients showed mild deterioration that did not affect their activities of daily living and they achieved complete recovery at the latest follow-up examination. In contrast, severe dysfunction occurred frequently in the C-T2 group, without recovery at the latest follow-up.

CONCLUSIONS

The transection of the T2 nerve roots alone did not result in upper-extremity motor dysfunction; rather, the dysfunction is caused by the extensive dissection of the T1 and upper nerve roots. Therefore, transection of the T2 nerve roots in upper thoracic TES seems to be an acceptable procedure with satisfactory outcomes.

Postfixed brachial plexus radiculopathy due to thoracic disc herniation in a collegiate wrestler: a case report

OBJECTIVE

To present the unique case of a collegiate wrestler with C7 neurologic symptoms due to T1-T2 disc herniation.

BACKGROUND

A 23-year-old male collegiate wrestler injured his neck in a wrestling tournament match and experienced pain, weakness, and numbness in his left upper extremity. He completed that match and 1 additional match that day with mild symptoms. Evaluation by a certified athletic trainer 6 days postinjury showed radiculopathy in the C7 distribution of his left upper extremity. He was evaluated further by the team physician, a primary care physician, and a neurosurgeon.

DIFFERENTIAL DIAGNOSIS

Cervical spine injury, stinger/burner, peripheral nerve injury, spinal cord injury, thoracic outlet syndrome, brachial plexus radiculopathy.

TREATMENT

The patient initially underwent nonoperative management with ice, heat, massage, electrical stimulation, shortwave diathermy, and nonsteroidal anti-inflammatory drugs without symptom resolution. Cervical spine radiographs were negative for bony pathologic conditions. Magnetic resonance imaging showed evidence of T1-T2 disc herniation. The patient underwent surgery to resolve the symptoms and enable him to participate for the remainder of the wrestling season.

UNIQUENESS

Whereas brachial plexus radiculopathy commonly is seen in collision sports, a postfixed brachial plexus in which the T2 nerve root has substantial contribution to the innervation of the upper extremity is a rare anatomic variation with which many health care providers are unfamiliar.

CONCLUSIONS

The injury sustained by the wrestler appeared to be C7 radiculopathy due to a brachial plexus traction injury. However, it ultimately was diagnosed as radiculopathy due to a T1-T2 thoracic intervertebral disc herniation causing impingement of a postfixed brachial plexus and required surgical intervention. Athletic trainers and physicians need to be aware of the anatomic variations of the brachial plexus when evaluating and caring for patients with suspected brachial plexus radiculopathies.

Intercostobrachial nerves as a novel anatomic landmark for dividing the axillary space in lymph node dissection

Purpose. Our aim was to assess the feasibility of using the intercostobrachial nerves (ICBNs) as a possible new anatomic landmark for axillaries lymph node dissection in breast cancer patients. Background Data Summary. The preservation of ICBN is now an accepted procedure in this type of dissection; however, it could be improved further to reduce the number of postoperative complications. The axillary space is divided into lower and upper parts by the ICBN-a thorough investigation of the metastasis patterns in lymph nodes found in this area could supply new information leading to such improvements. Methods. Seventy-two breast cancer patients, all about to undergo lymph node dissection and with sentinel lymph nodes identified, were included in this trial. The lymph nodes were collected in two groups, from lower and upper axillary spaces, relative to the intercostobrachial nerves. The first group was further subdivided into sentinel (SLN) and nonsentinel (non-SLN) nodes. All lymph nodes were tested to detect macro- and micrometastasis. Results. All the sentinel lymph nodes were found under the intercostobrachial nerves; more than 10 lymph nodes were located in that space. Moreover, when lymph nodes macrometastasize or micrometastasize above the intercostobrachial nerves, we also observe metastasis-positive nodes under the nerves; when the lower group nodes show no metastasis, the upper group is also metastasis free. Conclusions. Our results show that the intercostobrachial nerves are good candidates for a new anatomic landmark to be used in lymph node dissection procedure.

Sensory disturbances and pain complaints after brachial plexus root injury: a prospective study involving 150 adult patients

After injury of the brachial plexus, sensory disturbance in the affected limb varies according to the extent of root involvement. The goal of this study was to match sensory assessments and pain complaints with findings on CT myelo scans and surgical observations. One hundred fifty patients with supraclavicular stretch injury of the brachial plexus were operated upon within an average of 5.4 months of trauma. Preoperatively, upper limb sensation was evaluated using Semmes-Weinstein monofilaments. Pain complaints were recorded for each patient. With lesions affecting the upper roots of the brachial plexus, hand sensation was largerly preserved. Sensory disturbances were identified over a longitudinal bundle on the lateral arm and forearm. In C8-T1 root injuries, diminished protective sensation was observed on the ulnar aspect of the hand. If the C7 root also was injured, sensation in the long finger was impaired. Eighty-four percent of our 64 patients with total palsy reported pain, versus just 47% of our 72 patients with upper type palsies. This rate dropped to 29% in the 14 patients with a lower-type palsy. C8 and T1, when injured, always were avulsed from the cord; when avulsion of these roots was the only nerve injury, pain was absent. Hand sensation was largely preserved in patients with partial injuries of the brachial plexus, particularly on the radial side. Even when T1 was the only preserved root, hand sensation was mostly spared. This indicates that overlapping of the dermatomal zones seems much more widespread than previously reported.