Craniofacial postherpetic neuralgia managed by stereotactic spinal trigeminal nucleotomy

Complete resolution of postherpetic neuralgia following pallidotomy: case report

The authors report on a female patient with left-dominant Parkinson's disease with motor fluctuations and levodopa-induced dyskinesias and comorbid postherpetic neuralgia (PHN), who underwent a right-sided pallidotomy. Besides a substantial improvement in her Parkinson's symptoms, she reported an immediate and complete disappearance of PHN. This neuralgia had been long-standing, pharmacologically refractory, and severe (preoperative Brief Pain Inventory [BPI] pain severity score of 8.0, BPI pain interference score of 7.3, short-form McGill Pain Questionnaire sensory pain rating index of 7 and affective pain rating index of 10, Present Pain Intensity rank value of 4, and visual analog scale score of 81 mm; all postoperative scores were 0). She continued to be pain free at 16 months postoperatively.This peculiar finding adds substantially to the largely unrecognized evidence for the role of the pallidum in pain processing, based on previous electrophysiological, metabolic, anatomical, pharmacological, and clinical observations. Therefore, the potential of the pallidum as a neurosurgical target for neuropathic pain warrants further investigation.

Microendoscopic stereotactic-guided percutaneous radiofrequency trigeminal nucleotractotomy

Object

Over the past few decades, various authors have performed open or stereotactic trigeminal nucleotractotomy for the treatment of neuropathic facial pain resistant to medical treatment. Stereotactic procedures can be performed percutaneously under local anesthesia, allowing intraoperative neurological examination as a method for target refinement. However, blind percutaneous procedures in the region of the atlantooccipital transition carry a considerably high risk of vascular injuries that may bring prohibitive neurological deficit or even death. To avoid such complications, the authors present the first clinical use of microendoscopy to assist percutaneous radiofrequency trigeminal nucleotractotomy. The aim of this article is to demonstrate intradural microendoscopic visualization of the medulla oblongata through an atlantooccipital percutaneous approach.

Methods

The authors present a case of severe postherpetic facial neuralgia in a patient who underwent the procedure and had satisfactory results. Stereotactic computational image planning for targeting the spinal trigeminal tract and nucleus in the posterolateral medulla was performed, allowing for an accurate percutaneous approach. Immediately before radiofrequency electrode insertion, a fine endoscope was introduced to visualize the structures in the cisterna magna.

Results

Microendoscopic visualization offered clear identification of the pial surface of the medulla oblongata and its blood vessels, the arachnoid membrane, cranial nerve rootlets and their entry zone, and larger vessels such as the vertebral arteries and the branches of the posterior inferior cerebellar artery.

Conclusions

The initial application of this technique suggests that percutaneous microendoscopy may be useful for particular manipulation of the medulla oblongata, increasing the safety of the procedure and likely improving its effectiveness.

Treatment of postherpetic trigeminal neuralgia with the Leksell gamma knife

Object. Postherpetic neuralgia is a syndrome characterized by intractable pain. Treatment of this pain has not yet been successful. Patients with postherpetic neuralgia will therefore benefit from any progress in the treatment strategy. The authors performed gamma knife radiosurgery (GKS) as a noninvasive treatment for postherpetic trigeminal neuralgia (TN) and evaluated the success rate for pain relief.

Methods. Between 1995 and February 1999, six men and 10 women were treated for postherpetic TN; conservative treatment failed in all of them. The median follow up was 33 months (range 8–34 months). The radiation was focused on the root of the trigeminal nerve in the vicinity of the brainstem (maximal dose 70–80 Gy in one fraction, 4-mm collimator). The patients were divided into five groups according to degree of pain relief after treatment.

A successful result (excellent, very good, and good) was reached in seven (44%) patients and radiosurgery failed in nine (56%). Pain relief occurred after a median interval of 1 month (range 10 days–6 months). No radiation-related side effects have been observed in these patients.

Conclusions. These results suggest that GKS for postherpetic TN is a relatively successful and safe method that can be used in patients even if they are in poor condition. In case this method fails, other treatment options including other neurosurgical procedures are not excluded.

Ultrasonic lesion of the trigeminal nucleus caudalis for deafferentation facial pain

The deafferentation facial pain syndrome, caused by physical, herpetic or tumourous lesions of the trigeminal sensory root, was successfully managed with ultrasonic trigeminal nucleotomy. The article presents this new surgical technique and its results in 14 patients suffering from severe facial pain and dysaesthesias.