Neurophysiological monitoring for the nucleus caudalis dorsal root entry zone operation

Surgical Interventions Targeting the Nucleus Caudalis for Craniofacial Pain: A Systematic and Historical Review

INTRODUCTION

Craniofacial pain is a prevalent group of conditions, and when refractory to conventional treatments, it poses a significant burden. The last decade has seen a renewed interest in the multimodal management of pain. Interventions targeting the nucleus caudalis (NC) of the trigeminocervical complex have been available as a treatment option since the 1930s, yet evidence for efficacy remains limited.

MATERIALS AND METHODS

We present a systematic review of the literature providing a historical perspective on interventions targeting the NC leading up to the present. We examine the various intervention techniques, clinical indications, and procedural efficacy. A novel outcome-reporting scheme was devised to enable comparison among studies owing to historically variable reporting methods.

RESULTS

A review of the literature revealed 33 retrospective studies published over the last 80 years, reporting on 827 patients. The most common technique was the open NC dorsal root entry zone nucleotomy/tractotomy; however, there has been an emergence of novel approaches such as endoscopic and spinal cord stimulation in the last ten years. Regardless of intervention technique or preoperative diagnosis, 87% of patients showed improvement with treatment.

CONCLUSIONS

The literature surrounding NC intervention techniques is reviewed. Recent advancements and the wide range of craniofacial pain syndromes for which these interventions show potential efficacy are discussed. New and less invasive techniques continue to emerge as putative therapeutic options. However, prospective studies are lacking. Furthermore, the evidence supporting even well-established techniques remains of poor quality. Future work should be prospective, use standard outcome reporting, and address efficacy comparisons between intervention type and preoperative diagnosis.

Open and Percutaneous Trigeminal Nucleotractotomy: A Case Series and Literature Review

INTRODUCTION

Nucleotractotomy is an efficient surgical technique that provides a high pain relief rate for specific clinical indications. There are two main approaches for performing this operation: an open and percutaneous technique.

METHODS

In the Federal Center of Neurosurgery (Novosibirsk, Russia) from 2016 to 2022, 13 trigeminal nucleotractotomies (7 open and 6 percutaneous) were performed in 12 patients (5 women and 7 men). The indications for surgery were deafferentation pain and chronic drug-resistant pain syndrome caused by malignancy in the facial region. A neurological examination was done on each patient 1 day before the surgery, right after the surgery, and at the follow-up (examinations were done after 1, 6, and 12 months, or when the patient independently applied to our hospital). In the early postoperative period, patients underwent brain MRI.

RESULTS

The average pain intensity score before nucleotractotomy on the 11-point (0-10) visual analog scale (VAS) was 9.3. The effectiveness of open interventions was somewhat higher; the average VAS score in the early postoperative period for the open technique was 1.57, in the group of patients who underwent percutaneous nucleotractotomy were 2.66. Complete regression of the pain syndrome was achieved in 6 patients; in 5 patients, the pain in the face decreased by more than 50%. One case had an unsatisfactory outcome. In the open-surgery group in the early postoperative period, according to MRI, the average length of the visualized area of signal change was longer (21.5 mm, the average diameter was 3.75 mm) than in a percutaneous nucleotractotomy group (16 mm, the average diameter was 3.75 mm). During the postoperative period (average follow-up 40 months), the pain recurred in 3 patients (30%): 2 patients after percutaneous nucleotractotomy (3 and 18 months after surgery) and in 1 patient 4 months after the open surgery. The mean VAS score at the last follow-up was 2.6.

CONCLUSION

Trigeminal nucleotractotomy is an effective approach to the treatment of intractable facial pain. Our experience suggests this technique is highly effective in patients with drug-resistant pain caused by craniofacial tumors and deafferentation conditions after treating trigeminal neuralgia.

A Review of Medical and Surgical Options for the Treatment of Facial Pain

Facial pain is a common medical complaint that is easily misdiagnosed. As a result, this pain often goes mistreated. Despite this, there are a variety of pharmacologic, surgical, and neuromodulatory options for the treatment of facial pain. In this review, the authors detail the forms of facial pain and their treatment options. They discuss the common medications used in the first-line treatment of facial pain and the second-line surgical and neuromodulatory options available to patients when pharmacologic options fail.

Dorsal root entry zone procedure and other surgeries for pain

Pain is a very common symptom that often serves a protective function. It is typically treated medically. When pain becomes chronic and intractable, it no longer serves a protective function and often requires more aggressive forms of treatment. Many types of surgeries can be performed for the management of pain. These surgeries can involve ablation (destruction) or augmentation (stimulation or facilitation) of some part of the nervous system. In many of these surgeries, neurophysiologic intraoperative monitoring (NIOM) is not needed, however, in others neuromonitoring serves a mapping and monitoring purpose. The prototype of pain surgery for this chapter is the dorsal root entry zone (DREZ) procedure. Both mapping and monitoring can help improve lesioning precision and outcomes in this surgery. In this chapter, the DREZ procedures and other surgeries for primarily pain relief in which NIOM is used are discussed. Surgeries, such as spinal stenosis, in which pain relief is important but not the sole purpose, are not discussed here and are covered elsewhere.

Percutaneous Computed Tomography-Guided Radiofrequency Ablation of Spinal Trigeminal Tract and Nucleus Caudalis for Refractory Trigeminal Neuropathic Pain: 2-Dimensional Operative Video

This is a surgical video of a computed tomography (CT)-guided percutaneous radiofrequency ablation of the spinal trigeminal tract and nucleus caudalis for refractory trigeminal neuropathic pain.1,2 Many have contributed historically, among them, Sjoqvist3 in 1938 first described destruction of the descending medullary trigeminal tractus via open craniotomy.3-6 In 1967 and 1968, Crue7 and Hitchcock8 independently developed a percutaneous tractotomy technique. Although Kanpolat9,10 first described the use of CT imaging for percutaneous creation of a single tractotomy/nucleotomy lesion resulting in satisfactory pain relief for 85% of patients. The spinal trigeminal tract is a descending fiber pathway containing central processes of first-order afferent neurons from cranial nerves V, VII, IX, and X. The spinal trigeminal nucleus is the terminal projection of the spinal trigeminal tract comprised of 3 subnuclei: oralis, interpolaris, and caudalis. The nucleus caudalis is the most caudal of the 3 subdivisions of the spinal trigeminal nucleus and houses the cell bodies of second-order afferent neurons critical in nociception of the face. Lesioning of the spinal trigeminal tract and nucleus caudalis can provide pain relief without affecting facial sensation or trigeminal motor function.9,11-13 Percutaneous radiofrequency ablation is performed using anatomical landmarks, serial CT scans, impedance monitoring, and functional confirmation to ensure appropriate insertion of the probe to the target of interest prior to lesioning. This procedure remains uncommon in current practices even among functional neurosurgery pain specialists but offers a low-risk, minimally invasive treatment option for refractory facial pain.14 This procedure was done under Institutional Review Board guidance (H-41228: retrospective chart review of patients undergoing spine surgery for pain). The risks and benefits were explained, and the patient consented to videography/procedure. Images in the video used with permission from the following: Carter HV. Anatomy of the Human Body. Wikimedia Commons [Public Domain]. https://commons.wikimedia.org/wiki/File:Gray698.png. Published 1918. Accessed June 30, 2019; Carter HV. Anatomy of the Human Body. Wikimedia Commons [Public Domain]. https://commons.wikimedia.org/wiki/File:Gray784.png. Published 1918. Accessed June 30, 2019; Reprinted from Kanpolat Y, Kahilogullari G, Ugur HC, Elhan AH, CT-guided percutaneous trigeminal tractotomy-nucleotomy, Neurosurgery, 2008, 63(1 Suppl 1), ONS147-53; discussion ONS153-5, by permission of the Congress of Neurological Surgeons; Madhero88. Onion Distribution of Pain and Temperature Sense by Trigeminal Nerve. Wikimedia Commons [Creative Commons BY 3.0 license]. https://en.wikipedia.org/wiki/File:Onionskinddistribution.svg#/media/File:Onionskinddistribution.svg. Accessed June 30, 2019.

Dorsal root entry zone lesion, midline myelotomy and anterolateral cordotomy

This review encompasses the most common spinal cord lesioning procedures used for the treatment of pain: dorsal root entry zone lesioning, open cordotomy, percutaneous cordotomy, and midline myelotomy. A literature review and summary of each technique regarding relevant anatomy, patient selection, surgical technique, outcomes, and complications are discussed. A general review of somatic and visceral pain pathways of the spinal cord is included, as each procedure requires an understanding of the advantages and disadvantages of various approaches to lesioning the spinal cord for pain. Neurosurgical education of these rarely used procedures needs to be included in residency and fellowship training.

Computed Tomography-guided Percutaneous Trigeminal Tractotomy-nucleotomy

Objective:

The destruction of the descending trigeminal tractus in the medulla is known as trigeminal tractotomy (TR), whereas the lesioning of the nucleus caudalis is known as trigeminal nucleotomy (NC). Trigeminal TR and/or NC procedures can be used in a large group of pain syndromes, such as glossopharyngeal, vagal, and geniculate neuralgias, atypical facial pain, craniofacial cancer pain, postherpetic neuralgias, and atypical forms of trigeminal neuralgia.

Methods:

In this study, anatomic and technical details of the procedure and the experience gained from 65 patients over the course of 20 years are discussed. Patients’ pain scores and Karnofsky Performance Scale scores were evaluated pre- and postoperatively (postoperative Day 1).

Results:

The best results were obtained in the second-largest group (vagoglossopharyngeal neuralgia, n = 17) and in geniculate neuralgia (n = 4). Patients with atypical facial pain (n = 21; 13 women, eight men) accounted for the largest group to undergo computed tomography-guided TR-NC surgery; pain relief was achieved in 19 of these patients. In the third-largest group (craniofacial and oral cancer pain, n = 13), 11 of 13 patients were successfully treated with TR-NC. Four of five patients with failed trigeminal neuralgia were also effectively treated with TR-NC.

Conclusion:

We propose that computed tomography-guided TR-NC provides direct visualization of the target-electrode relation and can be considered a first-step procedure in patient management. In view of its high efficacy, low complication rate, and minimal invasiveness, computed tomography-guided trigeminal TR-NC is a safe and effective procedure in the treatment of intractable facial pain syndromes.

Spinal and Nucleus Caudalis Dorsal Root Entry Zone Operations for Chronic Pain

Objective:

Dorsal root entry zone (DREZ) operations came into medical practice after the demonstration of increased electrical activity in the dorsal horn of the spinal cord and brainstem in patients with deafferentation of the central nervous system after injury to these areas. The aim of the study was to describe the technique and the effectiveness of spinal DREZ and nucleus caudalis (NC) DREZ operations, which may be the treatments of choice in unique chronic pain conditions that do not respond to medical therapy or any other surgical methods.

Methods:

Fifty-five patients (44 spinal, 11 NC DREZ) underwent 59 (48 spinal, 11 NC DREZ) operations. There were 44 men and 11 women with a mean age of 46.4 years (range, 24–74 yr). The mean follow-up period was 72 months (range, 6 mo–20 yr). Follow-up assessments were performed with clinical examination on the first day and in the sixth and twelfth months postoperatively. Patients' pain scores and Karnofsky Performance Scale scores were also evaluated pre- and postoperatively.

Results:

The initial success rates for spinal and NC DREZotomy procedures were 77 and 72.5%, respectively. In the spinal DREZotomy group, mortality occurred in one patient (2.2%). There were two cases of transient muscle weakness (4.4%) and two of cerebrospinal fluid fistulae (4.4%). In the NC DREZotomy group, mortality occurred in one patient (9%). There were two cases of transient ataxia (18%) and two of transient hemiparesis (18%).

Conclusion:

Spinal and trigeminal NC DREZ operations are effective in the treatment of intractable pain syndromes, especially in traumatic brachial plexus avulsions, segmental pain after spinal cord injury, postherpetic neuralgia, topographically limited cancer pain, and atypical facial pain.

The trigeminal tract and nucleus procedures in treatment of atypical facial pain

BACKGROUND

Atypical facial pain (AFP) is a throbbing pain situated deep in the eye and malar region, often radiating to the ear, neck, and shoulders. The pain generally is not within any dermatomal or anatomical boundaries. Atypical facial pain is distinct from trigeminal neuralgia and its variants. Therefore, the treatment of AFP should be specified. There is also no consensus in the treatment of AFP. Two different treatment procedures on the trigeminal tract and nucleus in a series of cases with AFP are presented.

METHODS

Between 1989 and 2005, 17 patients with AFP, in whom previous therapies had failed, underwent computed tomography (CT)-guided percutaneous trigeminal tractotomy-nucleotomy (TR-NC). One patient with unfavorable response to TR-NC underwent trigeminal dorsal root entry zone (DREZ) operation.

RESULTS

In the series with AFP, pain relief was achieved in all of the 17 cases. TR-NC provided maximum to inadequate degrees of pain relief in 16 of 17 patients. Dorsal root entry zone operation provided partial relief in 1 case. Neither mortality nor serious permanent complication was observed in the series.

CONCLUSION

Neurosurgical procedures such as TR-NC or trigeminal DREZ operation may be effective in the treatment of intractable AFP. The primary choice of operation should be TR-NC because this procedure is minimally invasive. Trigeminal DREZ operation, which affects a larger spread area, may follow if TR-NC fails. The indications and procedure of choice should be individually tailored, depending on the type of pain, underlying pathology, and experience of the surgeon.

Trigeminal nucleus caudalis dorsal root entry zone radiofrequency thermocoagulation for invalidating facial pain

INTRODUCTION

Facial pain syndromes occasionally result in desperate clinical settings completely unresponsive to any known therapy. Trigeminal nucleus caudalis dorsal root entry zone (DREZ) lesion is reported to be of benefit in such cases. In 1982 Nashold performed the first DREZ caudalis lesion in a patient with anaesthesia dolorosa.

PATIENTS AND METHODS

From 1994 to 2002 we have performed six DREZ caudalis lesions on five patients with extremely invalidating facial pain resistant to multiple pharmacological and surgical therapies. Pain was secondary to previous craniofacial surgery in all but one case. Pain presented as anaesthesia dolorosa or atypical facial pain so severe as to interfere with personal hygiene and even to prevent patients from oral feeding. A midline suboccipital approach was used and radiofrequency lesions (at the trigeminal nucleus caudalis in the cervicomedullary junction) were made at 1-mm intervals, 75 (o)C for 15 seconds each along the ipsilateral posterolateral sulcus from the cervical DREZ up to the obex.

RESULTS

Pain relief was complete and permanent in two patients. Three patients experienced significant improvement but pain recurred in two (weeks to a few months after the procedure). No patient's pain was made worse. A patient with persistent postoperative nasolabial pain was re-operated on (improving again but ultimately remaining unchanged). Air venous embolism related to the sitting position (3 patients) during surgery and bradycardia due to manipulation in medulla (2 patients) occurred during some of the procedures without any cardiovascular or neurological repercussion. Postoperative complications included mild and transient ataxia and monoparesia (3 patients).

DISCUSSION

Facial pain secondary to craniofacial surgery is known to be among the least responsive to treatment and a true challenge for pain clinicians. Actual indications for this procedure, operative technical details and the results of our series compared to previous reports are reviewed.

CONCLUSION

Trigeminal nucleus caudalis radiofrequency thermocoagulation is an effective neurosurgical procedure for the treatment of chronically debilitating and desperate facial pain syndromes with acceptable morbidity.