Surgical anatomy of the platysma motor branch as a donor for transfer in brachial plexus repair

The Functional Anatomy and Innervation of the Platysma is Segmental: Implications for Lower Lip Dysfunction, Recurrent Platysmal Bands, and Surgical Rejuvenation

BACKGROUND

Despite the central role of the platysma in face and neck rejuvenation, much confusion exists regarding its surgical anatomy.

OBJECTIVES

This study was undertaken to clarify the regional anatomy of the platysma and its innervation pattern and to explain clinical phenomena, such as the origin of platysmal bands and their recurrence, and the etiology of lower lip dysfunction after neck lift procedures.

METHODS

Fifty-five cadaver heads were studied (16 embalmed, 39 fresh, mean age 75 years). Following preliminary dissections and macro-sectioning, a series of standardized layered dissections were performed, complemented by histology and sheet plastination.

RESULTS

In addition to its origin and insertion, the platysma is attached to the skin and deep fascia across its entire superficial and deep surfaces. This composite system explains the age-related formation of static platysmal bands, recurrent platysmal bands after complete platysma transection, and recurrent anterior neck laxity after no-release lifting. The facial part of the platysma is primarily innervated by the marginal mandibular branch of the facial nerve, whereas the submandibular platysma is innervated by the "first" cervical branches, which terminate at the mandibular origin of the depressor labii inferioris. This pattern has implications for postoperative dysfunction of the lower lip, including pseudoparalysis, and potential targeted surgical denervation.

CONCLUSIONS

This anatomical study, comprised of layered dissections, large histology, and sheet plastination, fully describes the anatomy of the platysma including its bony, fascial, and dermal attachments, as well as its segmental innervation including its nerve danger zones. It provides a sound anatomical basis for the further development of surgical techniques to rejuvenate the neck with prevention of recurrent platysmal banding.

Contemporary Concepts of Primary Dynamic Facial Nerve Reconstruction in the Oncologic Patient

Transection of the facial nerve and its branches during extensive ablative procedures in the oncologic patient causes loss of control of facial mimetic muscles with severe functional and aesthetic sequelae. In such patients with advanced tumorous disease, copious comorbidities, and poor prognosis, rehabilitation of the facial nerve has long been considered of secondary priority. However, recent advances in primary facial nerve reconstruction after extensive resection demonstrated encouraging results focusing on rapid and reliable restoration of facial functions. The authors summarize 3 innovative approaches of primary dynamic facial nerve reconstruction by using vascularized nerve grafts, dual innervation concepts, and intra-facial nerve transfers.

A multi-layered nerve guidance conduit design adapted to facilitate surgical implantation

BACKGROUND AND AIMS

The gold standard procedure after a severe nerve injury is the nerve autograft, yet this technique has drawbacks. In recent years, progress has been made in the development of artificial nerve guides to replace the autograft, but no device has been able to demonstrate superiority. The present study introduces an adaptable foundation design for peripheral nerve regeneration.

METHODS

Silk fibroin was electrospun, creating a tri-layered material with aligned fiber surfaces and a randomly deposited fiber interior. This material was rolled into a micro-channeled conduit, which was then enveloped by a jacket layer of the same tri-layered material.

RESULTS

The proposed implant design succeeds in incorporating various desirable aspects of synthetic nerve guides, while facilitating the surgical implantation process for medical application. The aligned fiber surfaces of the conduit support axon guidance, while the tri-layered architecture improves its structural integrity compared with a fully aligned fiber material. Moreover, the jacket layer creates a small niche on each end which facilitates surgical implantation. An in vivo study in rats showed that nerve regeneration using this device was comparable to results after direct suture.

CONCLUSION

This proof-of-principle study, therefore, advances the development of tissue engineered nerve grafts by creating an optimized guidance conduit design capable of successful nerve regeneration.

Innervation of the Long Head of the Triceps Brachii in Humans-A Fresh Look

The triceps brachii muscle occupies the posterior compartment of the arm in humans and has three heads. The lateral and medial heads originate from the humerus and the long head arises from the infraglenoid tubercle of the scapula. All heads form a common tendon that inserts onto the olecranon and the deep antebrachial fascia on each side of it. Each head receives its own motor branch, which all are thought to originate from the radial nerve. However, several studies reported that the motor branch of the long head of the triceps (LHT) arises from the axillary nerve or the posterior cord. Here, we dissected 27 triceps in 15 cadavers to analyze the innervation of the LHT and found only radial innervation, which contradicts those studies. We examined studies reporting that the motor branch to the LHT in humans does not arise from the radial nerve as well as studies of the triceps in primates. Occasional variations of the innervation of skeletal muscles are normal, but a change of principal motor innervation from radial to axillary nerve has important implications. This is because the axillary nerve is often involved during shoulder injuries. The precise identification of the prevalence of axillary versus radial innervation is therefore clinically relevant for surgery, nerve drafting, and occupational and physical therapy. We conclude that the primary motor branch to the LHT arises from the radial nerve but axillary/posterior cord innervations occur occasionally. We suggest the development of a standard methodology for further studies. Anat Rec, 301:473-483, 2018. © 2018 Wiley Periodicals, Inc.

Anatomy of the Platysma Muscle

The aim of this paper was to review the anatomy the platysma systematically.The term "platysma AND anatomy" was used to search PubMed and Scopus, producing 394 and 214 papers, respectively. After excluding 95 duplicate titles, 513 abstracts and 98 full papers were reviewed. Among these 98 papers, 83 were excluded and 5 were added. Ultimately, 20 papers were analyzed.The most common aging-related change of the platysma was shortening (70.7%), followed by thinning (25.2%). The platysma most commonly originated from the upper portion of thorax anterior to clavicle (67.7%), followed by the subcutaneous tissue of the subclavicular and acromial regions (22.6%) and pectoralis (9.7%). The platysma ascended upward and medially (68.5%) or ascended from the clavicle to the face (31.5%). The platysma most commonly inserted on the cheek skin (57.5%), followed by the cutaneous muscles around the mouth (18.6%), the mandibulocutaneous ligament or zygoma (18.6%), and the parotid fascia or periosteum of the mandible (5.3%). The platysma was most commonly innervated by the cervical branch of the facial nerve (38.2%) or the cervical branch and mandibular branch of the facial nerve (60.5%), followed by the cervical plexus (0.6%), the cervical motor nucleus (0.6%), and the glossopharyngeal nerve (0.1%). The most common action of the platysma was drawing the lips inferiorly (83.3%) or posteriorly (12.9%). Four papers classified the platysma into subtypes; however, these classification strategies used arbitrary standards.Further studies will be necessary to establish the thickness of the platysma and to characterize age-related changes of the platysma.

The human platysma contains numerous muscle spindles

The mimic muscles are usually described as containing no muscle spindles. In the present publication the human platysma was reinvestigated concerning its content of corpuscular sensors. Serial sections through the platysma of seven donors revealed numerous muscle spindles but no Pacini corpuscules. The muscle spindles were located in the cranial two-thirds of the platysma, and were evenly distributed with a tendency to have more spindles in the lateral part of the muscle. Immunohistochemical staining with S46 antibodies revealed a predominance of nuclear bag fibers. The results point to an extended function of the platysma as an afferent center of the lower face mimic muscles.

Platysma Motor Nerve Transfer for Restoring Marginal Mandibular Nerve Function

BACKGROUND

Injuries of the marginal mandibular nerve (MMN) of the facial nerve result in paralysis of the lower lip muscle depressors and an asymmetrical smile. Nerve reconstruction, when possible, is the method of choice; however, in cases of long nerve gaps or delayed nerve reconstruction, conventional nerve repairs may be difficult to perform or may provide suboptimal outcomes. Herein, we investigate the anatomical technical feasibility of transfer of the platysma motor nerve (PMN) to the MMN for restoration of lower lip function, and we present a clinical case where this nerve transfer was successfully performed.

METHODS

Ten adult fresh cadavers were dissected. Measurements included the number of MMN and PMN branches, the maximal length of dissection of the PMN from the parotid, and the distance from the anterior border of the parotid to the facial artery. The PMN reach for direct coaptation to the MMN at the level of the crossing with the facial artery was assessed. We performed histomorphometric analysis of the MMN and PMN branches.

RESULTS

The anatomy of the MMN and PMN was consistent in all dissections, with an average number of subbranches of 1.5 for the MMN and 1.2 for the PMN. The average maximal length of dissection of the PMN was 46.5 mm, and in every case, tension-free coaptation with the MMN was possible. Histomorphometric analysis demonstrated that the MMN contained an average of 3,866 myelinated fiber counts per millimeter, and the PMN contained 5,025. After a 3-year follow-up of the clinical case, complete recovery of MMN function was observed, without the need of central relearning and without functional or aesthetic impairment resulting from denervation of the platysma muscle.

CONCLUSIONS

PMN to MMN transfer is an anatomically feasible procedure for reconstruction of isolated MMN injuries. In our patient, by direct nerve coaptation, a faster and full recovery of lower lip muscle depressors was achieved without the need of central relearning because of the synergistic functions of the PMN and MMN functions and minimal donor-site morbidity.

Cross-face neurotized platysmal muscular graft for upper eyelid reanimation: an anatomic feasibility study

BACKGROUND

Upper eyelid reanimation is one of the most important aspects of facial paralysis. The ideal method would be one that provided dynamic restoration of voluntary eye closure, involuntary blinking, and corneal reflex. Innervation to the platysma has shown to be relatively consistent, which would allow its use as a muscle graft neurotized by the contralateral healthy facial nerve for eyelid reanimation.

METHODS

Six fresh cadavers, 12 sides, were studied by dissecting the main trunk of the facial nerve and its cervicofacial division. Special attention was paid at the emergence of cervical branches to the platysma and its distribution on the undersurface of the muscle as well as its relationships with regional anatomic references.

RESULTS

One major branch with 1 or 2 accessory branches was found to emerge from the cervicofacial division, 1.5 cm distal to its origin in the facial nerve trunk. The major branch showed an oblique course, starting approximately 1 cm below the angle of the mandible and coursing toward the inferomedial border of the muscle. Harvest of a 3 × 2 muscle piece with a 10-cm-long neural pedicle was possible in all specimens. When presented over the superior eyelid, the nerve branch was found to reach the contralateral frontal branch of the facial nerve.

CONCLUSIONS

Innervation to the platysma muscle is relatively constant and consists of 1 major branch accompanied by 1 or 2 accessory branches. Harvest of a muscle flap with a neural pedicle long enough to reach the contralateral healthy side is anatomically feasible.

Bilateral platysma dystonia

Platysma dystonia is an involuntary movement of platysma muscle. It is a rare form of dystonia. In this case report, we would like to report a good result of peripheral nerve denervation for bilateral platysma dystonia case. A 58-years-old woman presented with an 8-years history of involuntary jerking movement of her bilateral platysma muscles. Oral medication was not effective. Microsurgical denervation of the facial nerves and its terminal branches to the platysma muscles were performed. Immediately after surgery, the patient showed considerable improvement. There were no complications. Selective peripheral denervation is useful for dystonia of the platysma muscles.

Transfer of the Platysma Motor Branch to the Accessory Nerve in a Patient With Trapezius Muscle Palsy and Total Avulsion of the Brachial Plexus

BACKGROUND AND IMPORTANCE:

To report on the successful use of a platysma motor nerve transfer to the accessory nerve in a patient with concomitant trapezius and brachial plexus palsy.

CLINICAL PRESENTATION:

A 20-year-old man presented with total avulsion of the right brachial plexus combined with palsies of the accessory and phrenic nerve. The patient was operated on 4 months after his injury. The accessory nerve was repaired via direct transfer of the platysma motor branch. The contralateral C7 root was connected to the musculocutaneous nerve, and the hemihypoglossal nerve was grafted to the suprascapular nerve. Two intercostal nerves were attached to the triceps long head motor branch.

CONCLUSION:

Within 20 months of surgery, the patient regained full reinnervation of the upper trapezius muscle. Elbow flexion scored M3+, and 30° active shoulder abduction was observed. Triceps reinnervation was poor. Platysma motor branch transfer to the accessory nerve is a viable alternative to reinnervate the trapezius muscle.

Combined Injury of the Accessory Nerve and Brachial Plexus

BACKGROUND:

Stretch-induced spinal accessory nerve palsy has been considered extremely rare, with only a few cases reported.

OBJECTIVE:

In 357 patients with stretch lesions of the brachial plexus, we investigated the prevalence, course, and surgical treatment of accessory nerve palsy.

METHODS:

Accessory nerve palsy was ascertained when the patient was unable to shrug the ipsilateral shoulder. Patients underwent brachial plexus reconstruction between 6 and 8 months after trauma. To confirm paralysis, during surgery, the accessory nerve was stimulated electrically.

RESULTS:

Accessory nerve palsy occurred in 19 of the 327 patients (6%) with upper type or complete palsy of the brachial plexus. Proximal injuries of the accessory nerve accompanied by voice alteration and complete palsy of the sternocleidomastoid and trapezius muscle occurred in 2 patients. Proximal palsy without vocal alterations was observed in 6 patients. Palsy of the trapezius muscle with preservation of the sternocleidomastoid muscle occurred in 11 patients. All 7 patients who demonstrated muscle contractions upon electrical stimulation of the accessory nerve during surgery recovered completely. Patients with surgical reconstruction of the accessory nerve through grafting (n = 2) or repair by platysma motor nerve transfer (n = 2) recovered active shoulder shrugging within 36 months of surgery. Seven of the 8 patients without accessory nerve reconstruction recovered from their drop shoulder and head tilt, but remained unable to shrug.

CONCLUSION:

If intraoperative electrical stimulation produces contraction of the upper trapezius muscle, no repair is needed. In proximal injuries, the platysma motor branch should be transferred to the accessory nerve; whereas in paralysis distal to the sternocleidomastoid muscle, the accessory nerve should be explored and grafted.