Dorsal scapular neuropathy causing rhomboids palsy and scapular winging

Topographic and morphometric anatomy of the proximal part of the dorsal scapular nerve

The dorsal scapular nerve (DSN) entrapment neuropathy has recently been recognized as a common cause of circumscapular pain and cases of winged scapula. Course of the nerve is important because the middle scalene muscle is frequently accessed for surgical treatments. Studies in the literature have not focused on the morphometric relationship of the DSN with the scalene muscles and its relationship with the long thoracic nerve (LTN). The neck regions of 13 adult cadavers were dissected bilaterally. The relationship of DSN with scalene muscles and LTN was evaluated. Cervical spinal nerves involved in the formation of the DSN were identified. Three types of DSN were observed based on the cervical spinal nerves from which it originates, five types of DSN from its relationship with the scalene muscles, and two types of DSN from its relationship with the LTN. The distance from where the nerve pierces the scalene muscle to the mastoid process was found to be greater in DSNs originating from C4 and C5 (93.85 ± 4.11 mm, p = 0.033). In DSNs not connected with LTN, the distance from where the nerve pierces the scalene muscle to the superior trunk/C5 (12.74 ± 7.73 mm, p = 0.008) and the length of the nerve within the scalene muscle (14.94 ± 5.5 mm, p = 0.029) were found to be statistically significantly greater. The topographic and morphometric anatomy of the proximal part of the DSN is important, especially for scalene muscles-focused surgical treatments and interscalene nerve blocks. We believe our results may guide clinical approaches and surgery.

Thoracic Outlet Syndrome Part II: Consensus on the Management of Neurogenic Thoracic Outlet Syndrome by the European Association of Neurosurgical Societies' Section of Peripheral Nerve Surgery

BACKGROUND

In the first part of this report, the European Association of Neurosurgical Societies' section of peripheral nerve surgery presented a systematic literature review and consensus statements on anatomy, classification, and diagnosis of thoracic outlet syndrome (TOS) along with a subclassification system of neurogenic TOS (nTOS). Because of the lack of level 1 evidence, especially regarding the management of nTOS, we now add a consensus statement on nTOS treatment among experienced neurosurgeons.

OBJECTIVE

To document consensus and controversy on nTOS management, with emphasis on timing and types of surgical and nonsurgical nTOS treatment, and to support patient counseling and clinical decision-making within the neurosurgical community.

METHODS

The literature available on PubMed/MEDLINE was systematically searched on February 13, 2021, and yielded 2853 results. Screening and classification of abstracts was performed. In an online meeting that was held on December 16, 2021, 14 recommendations on nTOS management were developed and refined in a group process according to the Delphi consensus method.

RESULTS

Five RCTs reported on management strategies in nTOS. Three prospective observational studies present outcomes after therapeutic interventions. Fourteen statements on nonsurgical nTOS treatment, timing, and type of surgical therapy were developed. Within our expert group, the agreement rate was high with a mean of 97.8% (± 0.04) for each statement, ranging between 86.7% and 100%.

CONCLUSION

Our work may help to improve clinical decision-making among the neurosurgical community and may guide nonspecialized or inexperienced neurosurgeons with initial patient management before patient referral to a specialized center.

Scapular winging due to rhomboid muscle paralysis: clinical assessment of 4 cases and anatomic study of the dorsal scapular nerve

BACKGROUND

A rare cause of scapular winging is rhomboid muscle paralysis secondary to dorsal scapular nerve (DSN) neuropathy. This paralysis causes winging of the medial border of the scapula with lateral rotation of its inferior angle. We report a series of 4 clinical cases of isolated DSN compression and the results of a specific rehabilitation protocol.

METHODS

A continuous clinical series of 4 patients with isolated rhomboid muscle deficiency was analyzed. Two patients were men and 2 were women, with a mean age of 40 years (range, 33-51 years). Three patients were right-handed and 1 was left-handed. Scapular winging always affected the dominant side. Two patients had occupations involving heavy physical work. The sports practiced involved exertion of the arms (dancing, boxing, gymnastics, muscle strengthening). A specific rehabilitation protocol was offered to the patients. In addition, 6 fresh cadaver dissections were performed to reveal possible DSN compression. Potential areas of compression were identified, in particular when the arm was raised.

RESULTS

The 4 patients presented with isolated DSN neuropathy were confirmed by electroneuromyographic testing. Total correction of scapular winging was not obtained in any patient. Three patients experienced residual pain with a neuropathic pain by the questionnaire for a Diagnosis of Neuropathic Pain (DN4) score of 2. The mean Quick-Disabilities of the Arm, Shoulder and Hand (DASH) score after treatment was 31.8 of 100. The mean ASES score was 56.2. Only 1 patient agreed to rehabilitation in a specialized center and underwent follow-up electroneuromyography. Signs of rhomboid muscle denervation were no longer present and distal motor latencies had become normal. In all cadaver dissections, the DSN originated from the C5 nerve root and did not pass through the middle scalene muscle. We identified a site of dynamic compression of the DSN by the upper part of the medial border of the scapula when the arm was raised.

DISCUSSION

DSN compression is conventionally attributed to the middle scalene muscle, but it is noteworthy that our study reveals the possibility of dynamic compression of the nerve by the proximal part of the medial border of the scapula, which occurs when the arm elevation is above 90°.

CONCLUSION

Our study reveals the possibility of dynamic compression of the DSN by the proximal part of the medial border of the scapula, which occurs when the arm is raised above 90°. In the absence of a surgical solution, conservative treatment is fundamental and requires management in a rehabilitation center with intervention by a multidisciplinary team.

Scapula alata: diagnosis and treatment by nerve surgery and tendon transfers

Scapula alata, also known as winged scapula, can lead to severe upper limb impairment. The shoulders' function is altered because the scapula, which supports the upper limb, is no longer stable. Typical scapula alata is described for serratus anterior palsy; however, any scapulothoracic muscle impairment may lead to scapular winging, particularly trapezius palsy, which is easy to miss, thus needed to be considered as a differential diagnosis. The diagnosis is difficult and based on various clinical tests and a thorough examination as well as electroneuromyography and MRI. The treatment ranges from conservative treatments for spontaneous recovery, nerve surgery including neurolysis, nerve transfers and nerve grafts for acute cases, to tendon transfers for more chronic cases and when nerve procedures are no longer feasible. Tendon transfers in serratus anterior palsy produce excellent results with a high rate of patient satisfaction and are described with the sternal or clavicular head of the pectoralis major; we describe our preferred technique in this article. Tendon transfers in trapezius palsy are performed with the levator scapulae, rhomboid minor and major muscles. Our preferred method is the Elhassan triple transfer. Scapula alata is a frequent and often misdiagnosed condition. Appropriate management can yield excellent results. Patients should be referred right away to specialized centers for surgery if recovery is not spontaneous.

Foraminal Origin of the Dorsal Scapular Nerve: An Anatomical Study

BACKGROUND

Although distal dorsal scapular nerve (DSN) anatomy has been well characterized, a paucity of literature exists detailing its proximal origin. To our knowledge, this is the first study examining DSN origin and its anatomy relative to the C5 nerve root, which may help localize pathology and provide insight into timing of DSN or C5 nerve root clinical and electrophysiological recovery.

METHODS

Eighteen cadaveric dissections were performed using a posterior-midline approach. Calipers were used for DSN branching and course characterization with statistical analysis completed for the following measurements: DSN diameter, C5 nerve root diameter, distance of DSN branch-point from the C5 ganglion, dural edge, and posterior foraminal tubercle (intra-vs. extraforaminal origin), as well as C5 root-SC branch-point distance.

RESULTS

Average/mean measurements (standard error) were as follows: DSN diameter: 3.7 mm (0.3 mm), C5 nerve root diameter: 6.2 mm (0.5 mm), DSN origin to C5 DRG: 12.4 mm (1.9 mm) distal, DSN origin to dural edge: 19. 6mm (1.8 mm), DSN origin to C5 root origin: 23.3 mm (2.2 mm), DSN origin to the posterior foraminal tubercle: 2.3 mm (2.5 mm) proximal/intraforaminal (first branch from C5 in all cases, and the majority [12 of 18, 67%] of DSNs originating from the C5 spinal nerve root within the foramen).

CONCLUSIONS

The C5 nerve root contributed to the DSN in all specimens that originated from the proximal, intraforaminal, C5 nerve root in the majority of specimens. As the first C5 nerve branch, surgeon knowledge of this proximal DSN pattern will help localize lesional pathology, as well as may help monitor clinical and electrophysiological recovery.

Contralateral trapezius transfer to treat scapular winging: A case report and review of literature

BACKGROUND

No dynamic technique, such as tendon transfer, has been described for scapular winging due to levator scapulae or rhomboid major and minor palsies resulting from an isolated dorsal scapular nerve injury. Thus, we evaluated how the contralateral trapezius compound osteomuscular flap transfer would work in stabilizing lateral scapular winging, and the case is reported here. A literature review was also conducted, and articles relevant to the case are presented.

CASE SUMMARY

A 37-year-old male patient who had sustained an isolated dorsal scapular nerve injury underwent reconstructive surgery using the contralateral trapezius compound osteomuscular flap transfer technique to treat scapular winging and the consequent pain, and to restore function from the shoulder impairment. As a result, the involved shoulder showed an improved Constant-Murley score, from 19.5% to 81.88%.

CONCLUSION

Contralateral trapezius osteomuscular flap transfer succeeded in stabilizing scapular winging in this case, improving shoulder function and affording pain relief.

Dorsal scapular nerve injury after trigger point injection into the rhomboid major muscle: A case report

BACKGROUND AND OBJECTIVE

We report the case of a patient who presented with right dorsal scapular neuropathy after a trigger point injection into the right rhomboid major muscle. Through a nerve conduction study and electromyography, we demonstrated dorsal scapular nerve injury in this patient.

CASE REPORT

A 38-year-old man complained that his right shoulder functioned less optimally during push-up exercises after a trigger point injection 4 weeks prior. Physical examination revealed mildly reduced right shoulder retractor muscle strength compared with the left side. We performed a nerve conduction velocity test and electromyography 5 weeks after the injection. The compound muscle action potential of the right dorsal scapular nerve showed low amplitude (left vs. right side: 5.2 vs. 1.6 mV) and delayed latency (left vs. right side: 4.9 vs. 6.8 ms). Positive sharp wave (1+) and mildly reduced recruitment were seen on electromyography of the rhomboid major muscle. The findings of the nerve conduction velocity test and electromyography indicated partial right dorsal scapular neuropathy. The nerve injury seemed to have been caused by the needle inserted during trigger point injection.

CONCLUSION

Clinicians should pay attention to the occurrence of dorsal scapular nerve injury when performing trigger point injection into the rhomboid muscle.

A Cadaveric Investigation of the Dorsal Scapular Nerve

Compression of the dorsal scapular nerve (DSN) is associated with pain in the upper extremity and back. Even though entrapment of the DSN within the middle scalene muscle is typically the primary cause of pain, it is still easily missed during diagnosis. The purpose of this study was to document the DSN's anatomy and measure the oblique course it takes with regard to the middle scalene muscle. From 20 embalmed adult cadavers, 23 DSNs were documented regarding the nerve's spinal root origin, anatomical route, and muscular innervations. A transverse plane through the laryngeal prominence was established to measure the distance of the DSN from this plane as it enters, crosses, and exits the middle scalene muscle. Approximately 70% of the DSNs originated from C5, with 74% piercing the middle scalene muscle. About 48% of the DSNs supplied the levator scapulae muscle only and 52% innervated both the levator scapulae and rhomboid muscles. The average distances from a transverse plane at the laryngeal prominence where the DSN entered, crossed, and exited the middle scalene muscle were 1.50 cm, 1.79 cm, and 2.08 cm, respectively. Our goal is to help improve clinicians' ability to locate the site of DSN entrapment so that appropriate management can be implemented.