Selective peripheral denervation of the levator scapulae muscle for laterocollic cervical dystonia

Improvements in Nerve Dissection Surgery Methodology for Spasmodic Torticollis Treatment

Spasmodic torticollis is the most common focal dystonia and is characterized by aberrant involuntary contraction of muscles of the neck and shoulders, which greatly affects patients' quality of life. Consequently, patients with this condition often desire treatment to alleviate their symptoms. The common clinical treatments for spasmodic torticollis include interventions such as drug therapy, botulinum toxin injections, and surgery. Surgical treatment is feasible for patients who do not respond well to other treatments or who are resistant to drugs. The gradual improvement of surgeons' understanding of anatomy and the ongoing developments in surgical techniques since their advent in the 1640s have resulted in many innovative surgical approaches that have led to improvements in the treatment of spasmodic torticollis. Previously used surgical treatments that result in uncertain outcomes, various postoperative complications, and serious damage to motor functions of the head and neck have gradually been discontinued. Nerve dissection surgery is the most common surgical treatment for spasmodic torticollis. This article reviews existing research on nerve dissection surgery for the treatment of spasmodic torticollis and the history of its development, along with the advantages and disadvantages of various surgical improvements. This article aims to provide clinicians with practical advice.

The nerve to the levator scapulae muscle as donor in brachial plexus surgery: an anatomical study and case series

OBJECTIVE

Nerve transfers are commonly used in treating complete injuries of the brachial plexus, but donor nerves are limited and preferentially directed toward the recovery of elbow flexion and shoulder abduction. The aims of this study were to characterize the anatomical parameters for identifying the nerve to the levator scapulae muscle (LSN) in brachial plexus surgery, to evaluate the feasibility of transferring this branch to the suprascapular nerve (SSN) or lateral pectoral nerve (LPN), and to present the results from a surgical series.

METHODS

Supra- and infraclavicular exposure of the brachial plexus was performed on 20 fresh human cadavers in order to measure different anatomical parameters for identification of the LSN. Next, an anatomical and histomorphometric evaluation of the feasibility of transferring this branch to the SSN and LPN was made. Lastly, the effectiveness of the LSN-LPN transfer was evaluated among 10 patients by quantifying their arm adduction strength.

RESULTS

The LSN was identified in 95% of the cadaveric specimens. A direct coaptation of the LSN and SSN was possible in 45% of the specimens (n = 9) but not between the LSN and LPN in any of the specimens. Comparison of axonal counts among the three nerves did not show any significant difference. Good results from reinnervation of the major pectoral muscle (Medical Research Council grade ≥ 3) were observed in 70% (n = 7) of the patients who had undergone LSN to LPN transfer.

CONCLUSIONS

The LSN is consistently identified through a supraclavicular approach to the brachial plexus, and its transfer to supply the functions of the SSN and LPN is anatomically viable. Good results from an LSN-LPN transfer are observed in most patients, even if long nerve grafts need to be used.

[Historical view on the pathogenesis and surgical treatment of cervical dystonia]

In the past few decades, approaches to surgical treatment of dystonia passed through paradigmatic shift. Intradural upper cervical anterior rhizotomy was replaced by selective peripheral denervation with lesser spectrum of side-effects. Such techniques as microvascular decompression of accessory nerve or spinal cord stimulation for cervical dystonia were abandoned due to lack of proven efficacy. Introducing globus pallidus interna (GPi) DBS in 1990's to treat all types of dystonia, including cervical dystonia, was a fundamental factor. With the growing body of knowledge on the pathophysiology of dystonia, GPi DBS appears to be the most expedient, effective and safe method with limited indications to peripheral destructive procedures.

Unilateral pallidotomy as a potential rescue therapy for cervical dystonia after unsatisfactory selective peripheral denervation

OBJECTIVE

Selective peripheral denervation (SPD) is a widely accepted surgery for medically refractory cervical dystonia (CD), but when SPD has failed, the available approaches are limited. The authors investigated the results from a cohort of CD patients treated with unilateral pallidotomy after unsatisfactory SPD.

METHODS

The authors retrospectively analyzed patients with primary CD who underwent unilateral pallidotomy after SPD between April 2007 and August 2019. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) was used to evaluate symptom severity before surgery, 7 days postsurgery, 3 months postsurgery, and at the last follow-up. TWSTRS subscores for disability and pain and the 24-item Craniocervical Dystonia Questionnaire (CDQ-24) were used to assess quality of life.

RESULTS

At a mean final follow-up of 5 years, TWSTRS severity subscores and total scores were significantly improved (n = 12, mean improvement 57.3% and 62.3%, respectively, p = 0.0022 and p = 0.0022), and 8 of 12 patients (66.7%) were characterized as responders (improvement ≥ 25%). Patients with rotation symptoms before pallidotomy showed greater improvement in TWSTRS severity subscores than those who did not (p = 0.049). The most common adverse event was mild upper-limb weakness (n = 3). Patients' quality of life was also improved.

CONCLUSIONS

Unilateral pallidotomy seems to offer an effective and safe option for patients with CD who have otherwise experienced limited benefits from SPD.

Effectiveness of selective peripheral denervation in combination with pallidal deep brain stimulation for the treatment of cervical dystonia

BACKGROUND

Selective peripheral denervation (SPD) and deep brain stimulation of the globus pallidus (GPi-DBS) are available surgical options for patients with medically refractory cervical dystonia (CD). There are few data available concerning whether patients who have unsatisfactory treatment effects after primary surgery benefit from a different type of subsequent surgery. The aim of this study was to assess whether combining these surgical procedures (SPD plus GPi-DBS) was effective in patients with unsatisfactory treatment effects after their initial surgery.

METHODS

Forty-one patients with medically refractory idiopathic CD underwent SPD and/or GPi-DBS. Patients who were dissatisfied with their primary surgery (SPD or GPi DBS) elected to subsequently undergo a different type of surgery. These patients were assessed with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).

RESULTS

SPD alone and GPi-DBS alone were performed in 16 and 21 patients, respectively. Four patients had unsatisfactory treatment effects after the initial surgery and subsequently underwent another type of surgery. Among them, two patients with persistent dystonia after SPD subsequently underwent GPi-DBS, and two other patients who had insufficient treatment effects following GPi-DBS were subsequently treated with SPD. All of these patients experienced sustained improvement from the combined surgical procedures according to the TWSTRS score during a long-term follow-up of 12-90 months.

CONCLUSIONS

Patients with unsatisfactory treatment effects after an SPD or GPi-DBS experienced improvement from subsequently undergoing other types of surgery. Therefore, combined surgical procedures are additional surgical options with good outcomes in the treatment of patients with residual symptoms after their initial surgery.

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.

Cervical Dystonia

Cervical dystonia, which is the most common form of focal dystonia, presents with sustained neck spasms, abnormal head posture, head tremor, and pain. One of the interesting and unique features of cervical dystonia is the geste antagoniste. There is not a well-described pathophysiology for cervical dystonia, but several hypotheses report involvement at the central and peripheral level. Treatment options include: oral medical therapy, botulinum toxin injection, and surgery. Oral medical therapy has limited efficacy in control of the symptoms of cervical dystonia. Two types of botulinum toxin, types A and B, are being used for treatment of cervical dystonia, with equivalent benefit. Surgery is an option when other treatments fail or become ineffective. The surgical procedures are brain lesioning, brain stimulation, and peripheral surgical intervention. Several trials are currently ongoing in the United States and Europe to evaluate the efficacy of deep brain surgery in cervical dystonia.

Multimodal neurosurgical strategies for the management of dystonias

Dystonia have many subtypes, and is classified as focal, segmental and generalized. As for focal dystonia, spasmodic torticollis (cervical dystonia) and writer's cramp are most common. Cervical dystonia is mainly treated effectively with selective peripheral denervation, and task specific focal dystonia of the hand (writer's cramp) is effectively alleviated by stereotactic ventro-oral thalamotomy. Generalized dystonia is dramatically improved with deep brain stimulation of the globus pallidus interna. Because the majority of dystonia is medically refractory and surgical treatment results in marked improvement, the authors strongly believe that dystonia should be regarded as a definite neurosurgical indication. Based on personal experience of nearly 200 cases of dystonia surgery, the authors describe a multimodal approach to various types of dystonias. Also we discuss possible relation between dystonias and psychiatric conditions, and future new indication of dystonia surgery.