J Neurosurg 116:331–335, 2012
Microendoscopic stereotactic-guided percutaneous radiofrequency trigeminal nucleotractotomy Technical note Manoel Jacobsen Teixeira, M.D., Ph.D., Fabrício Freitas de Almeida, M.D., Ywzhe Sifuentes Almeida de Oliveira, M.D., and Erich Talamoni Fonoff, M.D., Ph.D. Pain Center and Division of Functional Neurosurgery of Department of Neurology, University of São Paulo Medical School, São Paulo, Brazil 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. (DOI: 10.3171/2011.8.JNS11618)
T
Key Words • pain • percutaneous nucleotractotomy • endoscopy • radiofrequency • medulla oblongata
tractotomy, nucleotomy, and lesioning of the nucleus caudalis dorsal root entry zone have been used as percutaneous or open techniques to destroy the nociceptive fibers from CNs V, VII, IX, and X that converge to their nuclear relay neurons within the spinal trigeminal caudalis nucleus.1,3,6–8 These techniques are primarily used to alleviate pain associated with deafferentation on the face in cases of postherpetic neuralgia or trigeminal neuropathy caused by ablative procedures in the trigeminal nerve or ganglion for the treatment of either trigeminal neuralgia or cancer pain, or caused by radiation in actinic trigeminal neuropathy.1,3,6–8,14,24 For years, surgical interruption of the trigeminal descending tract was performed using an open technique. Despite its efficacy, even after modifications1 the original open trigeminal tractotomy presented some disadvantagrigeminal
Abbreviations used in this paper: CN = cranial nerve; RF = radiofrequency; VAS = visual analog scale.
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es over the percutaneous technique. The open procedure requires considerable manipulation of muscles, resection of laminae of the upper cervical levels and posterior aspects of the axis and atlas, and finally a small occipital craniectomy, adding to the procedure time. The main disadvantage of this technique is that it requires general anesthesia, precluding the possibility of patient participation and intraoperative neurological examination for target refinement.23 Therefore, the open technique requires a considerably greater number of RF lesions to achieve satisfactory pain control, which consequently adds to increased morbidity and possible neurological deficits.16,21 To provide a less invasive procedure, Crue et al.2 developed the stereotactic technique, which was later modified by Hitchcock.10 The minimally invasive nature of stereotactic procedures has made percutaneous manipulation of This article contains some figures that are displayed in color online but in black and white in the print edition.
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M. J. Teixeira et al. this region possible under local anesthesia with the possibility of patient participation. The accuracy of stereotaxy was added to patient guidance by intraoperative mapping for controlled electrical stimulation through the RF probe inserted into the target site at dorsolateral aspects of the medulla oblongata. However, the potential high risk of vascular injuries and potentially fatal subarachnoid hemorrhages caused the procedure to be abandoned by most authors.11,18 Only a few neurosurgical centers have continued to perform percutaneous procedures after technical improvements.13,23 Instead, most patients with refractory deafferentation facial pain syndromes are referred for motor cortex stimulation. However, the results of this more conservative technique are not satisfactory in a considerable number of patients, which leaves these patients without any treatment possibilities.15 Here, we demonstrate that microendoscopic exploration of the surgical field can be used in stereotactic procedures at the cranium-cervical transition by inserting a fine endoscope to combine the minimally invasive nature of the percutaneous approach with the accuracy of a computer-guided stereotactic procedure, thereby avoiding the risk of injuries to neural tissue and blood vessels (Video 1). Video 1. Clip showing the dynamic microendoscopic visualization of the posterolateral aspects of the medulla oblongata after the occipitocervical stereotactic percutaneous approach. It is possible to identify clearly the vessels in the pial surface of medulla and arachnoid trabeculae moving with CSF pulsation. Click here to view with Windows Media Player. Click here to view with Quicktime.
Case Report History and Examination. This 43-year-old man with previous immunodeficiency was diagnosed with postherpetic neuralgia that was initially treated by oral medication. He experienced partial improvement. One year after the development of the facial neuralgia, oral medication no longer controlled pain even at very high doses (gabapentin [4800 mg/day], nortriptyline [100 mg/day], and tramadol [600 mg/day]; or methadone [90 mg/day]). Despite oral medication, the patient experienced very intense burning pain (VAS Score 8–10/10), frequent shocklike sensations, and unbearable neuropathic pruritus associated with intolerable allodynia in the territory of the first 2 trigeminal divisions. A neurological examination revealed light tactile and pinprick hyperesthesia associated with a diminished sense of vibration, and mechanical and thermal allodynia in the territory of the first and second trigeminal branches (Fig. 1 left). No changes were detected in 2-point discrimination. A trial with transcranial magnetic stimulation in the motor cortex was performed, but no satisfactory improvement was observed. As motor cortex stimulation was not available at that time, trigeminal nucleotractotomy was offered, and after obtaining informed consent, the procedure was performed according to the following technique. Operation. Stereotactic trigeminal nucleotractotomy was performed under local anesthesia. The morning of 332
Fig. 1. Left: Illustration of the sensory impairment in the left V1 and V2 segments caused by the neuropathic changes related to the postherpetic neuralgia before the procedure. The circles denote the areas of allodynia, the dark gray area designates the area of tactile and thermal hypesthesia, and the open triangles indicate the areas of hyperalgesia. The black triangle indicates the point of greatest pain and allodynia. Right: Illustration depicting the results of the sensory examination performed 18 months after the procedure, showing the area of residual pain (black triangle). Allodynia and hyperalgesia were eradicated by the procedure, and there was no change in the area of hypothesia.
the procedure, a contrast-administered stereo-CT scanning study (TM-Micromar frame, Micromar) was performed and fused with the MR images (Gd-enhanced T1weighted volumetric sequences) using computer software (MNPS, Mevis) for target and trajectory planning (Fig. 2). This technique provided accurate representation of the brainstem, cerebellum, upper cervical spinal cord, occipitocervical bone structures, and the greater arteries within the cisterna magna. The target plan aimed the point in the distal medulla oblongata at the level of the obex, 5 mm from the midline. The probe trajectory was drawn from the intended target through the posterolateral atlantooccipital interspace with a lateral angle of 35° laterally from midline. Under light sedation, the patient was placed in a lateral position with his head firmly fixed in the stereotactic frame. After a local anesthetic was administered, the 18-gauge guide cannula was inserted percutaneously according to the stereotactic trajectory plan, and it gently punctured the dura mater. A fine endoscope (0.9-mmthick microendoscope, MYELOTEC, Inc.) was inserted through the cannula for direct view of the anatomy in the cisterna magna. This endoscopic device renders a 70° field of view at 40× a 0° angle of view, which provides a clear image through the CSF. The endoscopic visualization offered clear identification of the pial surface of the medulla oblongata and its blood vessels, the arachnoid membrane, the CN rootlets and their entry zone, and larger vessels such as the vertebral arteries and the branches of the posterior inferior cerebellar artery (Fig. 3). After removal of the endoscope, an RF electrode (1-mm exposed fine tip, 0.27 mm in diameter; Radionics) was inserted through the same cannula, reaching the pial surface of the medulla at the determined point. Fortunately, the trajectory in this case was clear of vessels. In cases in which vessels are in the exact pathway of the endoscope, a new trajecJ Neurosurg / Volume 116 / February 2012
Microendoscopic percutaneous trigeminal nucleotractotomy
Fig. 2. Preoperative sagittal (A), coronal (B), and axial (C) T1-weighted MR images showing the target planning for trigeminal nucleotractotomy in the medulla oblongata as well as the probe trajectory. These images were obtained from the intraoperative programming computer software and were enhanced for illustration of this report. The probe trajectory was programmed from the skin through the posterolateral atlantooccipital interspace into the cisterna magna.
tory must be oriented by changing the angles of the stereotactic apparatus to avoid contact between the vessels and the probe. Continuing the procedure, conventional recording of tissue impedance guided the insertion of the electrode into the medulla (approximate impedance: CSF, 200 W; and medulla, 800 W). Further controlled electrical stimulation (75 Hz and 1-msec pulse width) provided target refinement by eliciting a tingling sensation over the ipsilateral facial area. The target was confirmed once the patient noted that the area of evoked sensation included the painful spot. This control was possible because the patient was awake and fully participating in the procedure at this time. The lesion was then made by applying RF, reaching a temperature of 75°C during 60 seconds. In this particular case, 3 consecutive lesions in the longitudinal axis of the medulla were enough for satisfactory thermoanalgesia on the ipsilateral side of the face reaching the V1 and V2 territory. The first lesion was made at the level of the obex, and the other two lesions were made caudal to the first to include the upper and more peripheral portions of the face and forehead. Immediately after the lesions were made, the microendoscope was again inserted into the CSF space to view the spot of the electrode insertion on the pial surface of medulla. There was no bleeding or other complication during the procedure. No CSF leak was detected during the early or late postoperative period. Figure 4 shows the changes of the RF lesion on postoperative MR images.
Postoperative Course. In addition to immediate pain relief and resolution of allodynia and neuropathic pruritus, tactile and thermal hypesthesia (especially in the left V1) and an expected mild ipsilateral upper-limb ataxia remained but improved within 4 weeks. No additional postoperative neurological deficits were observed. The patient was reexamined at last follow-up (26 months), maintaining pain relief (VAS Score 2) in the very limited region of
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V2 (Fig. 1 right). He also was able to gradually reduce his medication doses to nortriptyline (25 mg/day).
Discussion
Although deafferentation trigeminal pain syndromes are not very common, their severity and resistance to medication are often observed in patients suffering from these conditions. Postherpetic neuralgia, anesthesia dolorosa, and other deafferentation pain syndromes such as radiation-induced trigeminal neuropathy and Wallenberg syndrome are the most frequently described.11,19 Initially, a variety of surgical procedures have been proposed for pain relief, leading to partial improvement in, but sometimes worsening of, the pain process. However, satisfactory pain outcome was only reached when the surgical
Fig. 3. Endoscopic view of the brainstem surface at the level of the posterolateral medulla.
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Fig. 4. Postoperative MR images showing the lesion spot in the posterolateral aspects of the medulla, represented by a hyperintense dot (arrows) surrounded by hypointense edema in sagittal (A), coronal (B), and axial (C) T1-weighted images and surrounding edema on the T2-weighted image (D).
procedures were based on the knowledge about the functional anatomy of the brainstem and on the pathophysiology of neuropathic pain. The complex sensory function of facial structures is mediated by the entire trigeminal complex, whereas the spinal trigeminal nucleus is responsible for the integration and processing of nociceptive information from the face.22 The topographic arrangement of the subnucleus caudalis of the trigeminal spinal nucleus has an onion-skin pattern, in which the central or oral region of the face projects into the rostral part of the nucleus up to the obex and the peripheral areas project into its caudal part down to the level of C-4.12,17,20 In 1937, Sjöqvist20 performed a trigeminal tractotomy through the open procedure. Since then, the technique underwent several modifications, with Kunc et al.14 developing the high cervical access and Fox et al.6,7 reporting on the percutaneous freehand technique. Thus, Crue et al.2 developed the stereotactic procedure, which was later modified by Hitchcock and Schvarcz.11 In 1972, these latter authors published their promising results of RF lesioning in the descending trigeminal tract for the treatment of postherpetic trigeminal pain. This technique made the procedure more accurate and reduced the number of complications of the open technique, such as ipsilateral ataxia, paralysis of the recurrent laryngeal nerve, contralateral analgesia, contralateral vocal cord paralysis, gait disturbance, and loss of postural stability.8 In addition, the development of percutaneous procedures contributed to the expansion of the knowledge of functional anatomy of the trigeminal nucleus. Monopolar stimulation of the cervicomedullary trigeminal nuclear neurons in conscious patients during percutaneous trigeminal tractotomies confirmed the onion-skin pattern of functional areas of the spinal trigeminal nucleus in humans.22 At upper cervical levels, responses from all trigeminal nerve branches, including 334
those involved in the innervation of the perioral regions, and from CNs VII, IX, and X are easily elicited.3 However, to treat pain in the central area of the face and inside the oral cavity, the lesion must be made far enough upward to involve the most rostral part of the nucleus.7,9,19 Moreover, the RF stereotactic approach differs from peripheral procedures because it disrupts not only the afferent but also the second-order neurons and tracts of the trigeminal spinal complex.11 As mentioned previously, the target at the level of the obex is used as a standard starting point for trigeminal nucleotractotomy, followed by intraoperative refinement. The ablative procedure performed according to this technique enables careful microstimulation mapping, thereby avoiding superfluous lesions and consequently minimizing undesired neurological deficits.1 More recently, Kanpolat et al.13 described technical improvement of the percutaneous procedure guided by intraoperative CT. The option of mapping the functional anatomy of the nucleus added great advantages to the stereotactic or CT-guided percutaneous techniques. However, none of these advantages overcame the risk of vascular injuries. Although nucleotractotomy became less invasive and produced encouraging results even for drug-resistant deafferentation pain syndromes, presently it is not widely used probably because of the high risk of vascular injury. The intent of this report is to demonstrate that microendoscopic assistance has emerged as an adjuvant technique that could increase the safety and therefore expand the range of spinal percutaneous procedures.5 In 1974, Olinger and Ohlhaber17 developed a narrow fiber optic needle endoscope that was thin enough to pass through a 17-gauge spinal needle. Although no practical progress in the surgical field was made, they proposed that such a device could be used for operations in the spinal canal, J Neurosurg / Volume 116 / February 2012
Microendoscopic percutaneous trigeminal nucleotractotomy permitting direct vision through limited exposures. Recently, our group described the use of fine endoscope to assist percutaneous cordotomies with a microendoscope that fits in an 18-gauge cannula.4
Conclusions
This report demonstrates that it is possible to use microendoscopy not only in freehand cordotomies but also in procedures in which there is a stereotactic-mounted apparatus. Current microendoscopic technology and new computer stereotactic programming software can be added to the standard stereotactic method, providing exceptional control with regard to the location and size of the lesion, reducing postoperative tissue trauma, and perhaps reducing the morbidity and mortality rates associated with percutaneous procedures in the craniocervical region. Disclosure This work was supported by a grant from FAPESP (Grant No. 2011/08529-5). Author contributions to the study and manuscript preparation include the following. Conception and design: Fonoff, Teixeira. Acquisition of data: all authors. Analysis and interpretation of data: all authors. Drafting the article: Fonoff, de Almeida, de Oliveira. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manus cript on behalf of all authors: Fonoff. Administrative/technical/material support: Teixeira. References 1. Cosman ER, Nashold BS, Bedenbaugh P: Stereotactic radiofrequency lesion making. Appl Neurophysiol 46:160–166, 1983 2. Crue BL, Todd EM, Carregal EJ, Kilham O: Percutaneous trigeminal tractotomy. Case report-utilizing stereotactic radiofrequency lesion. Bull Los Angeles Neurol Soc 32:86–92, 1967 3. Dallel R, Raboisson P, Auroy P, Woda A: The rostral part of the trigeminal sensory complex is involved in orofacial nociception. Brain Res 448:7–19, 1988 4. Fonoff ET, de Oliveira YS, Lopez WOC, Alho EJL, Lara NA, Teixeira MJ: Endoscopic-guided percutaneous radiofrequency cordotomy. J Neurosurg 113:524–527, 2010 5. Fonoff ET, Lopez WO, de Oliveira YS, Lara NA, Teixeira MJ: Endoscopic approaches to the spinal cord. Acta Neurochir Suppl (Wien) 108:75–84, 2011 6. Fox JL: Intractable facial pain relieved by percutaneous trigeminal tractotomy. JAMA 218:1940–1941, 1971 7. Fox JL: Percutaneous trigeminal tractotomy for facial pain. Acta Neurochir (Wien) 29:83–88, 1973 8. Garber JE, Hassenbuch SJ: Neurosurgical operations on the spinal cord, in Loeser JD, Chapman R, Turk DC (eds): Bonica’s Managements of Pain, ed 3. Philadelphia: Williams and Wilkins, 2001, pp 2023–2037
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9. Hamby WB, Shinners BM, Marsh IA: Trigeminal tractotomy; observations on 48 cases. Arch Surg 57:171–177, 1948 10. Hitchcock E: Stereotactic trigeminal tractotomy. Ann Clin Res 2:131–135, 1970 11. Hitchcock ER, Schvarcz JR: Stereotaxic trigeminal tractotomy for post-herpetic facial pain. J Neurosurg 37:412–417, 1972 12. Hu JW, Sessle BJ: Trigeminal nociceptive and non-nociceptive neurones: brain stem intranuclear projections and modulation by orofacial, periqueductal gray and nucleus raphe magnus stimuli. Brain Res 170:547–552, 1979 13. Kanpolat Y, Deda H, Akyar S, Cağlar S, Bilgiç S: CT-guided trigeminal tractotomy. Acta Neurochir (Wien) 100:112–114, 1989 14. Kunc Z: Treatment of essential neuralgia of the 9th nerve by selective tractotomy. J Neurosurg 23:494–500, 1965 15. Meyerson BA, Lindblom U, Linderoth B, Lind G, Herregodts P: Motor cortex stimulation as treatment of trigeminal neuropathic pain. Acta Neurochir Suppl (Wien) 58:150–153, 1993 16. Moffie D: Late results of bulbar trigeminal tractotomy. Some remarks on recovery of sensibility. J Neurol Neurosurg Psychiatry 34:270–274, 1971 17. Olinger CP, Ohlhaber RL: Eighteen-gauge microscopic-telescopic needle endoscope with electrode channel: potential clinical and research application. Surg Neurol 2:151–160, 1974 18. Piedimonte F, Schvarcz JR: Stereotactic trigeminal nucleotomy for dysesthetic facial pain. Stereotact Funct Neurosurg 68:175–181, 1997 19. Schvarcz JR: Craniofacial postherpetic neuralgia managed by stereotactic spinal trigeminal nucleotomy. Acta Neurochir Suppl (Wien) 46:62–64, 1989 20. Sjöqvist O: Studies on pain conduction in the trigeminal nerve: contribution to surgical treatment of facial pain. Acta Psychiatr Scand (Suppl) 17:1–139, 1938 21. Stookey BP, Ransohoff F: Trigeminal Neuralgia: Its History and Treatment. Springfield, IL: Charles C Thomas, 1959 22. Taren JA, Kahn EA: Anatomic pathways related to pain in face and neck. J Neurosurg 19:116–121, 1962 23. Teixeira MJ, Fonoff ET: Technique of trigeminal nucleotractotomy, in Lozano AM, Gildenberg PL, Tasker RR (eds): Textbook of Stereotactic and Functional Neurosurgery, ed 2. New York: Springer, 2009, Vol 1, pp 2097–2123 24. White JC, Sweet WH: Pain and the Neurosurgeon: a FortyYear Experience. Springfield, IL: Charles C Thomas, 1969 Manuscript submitted April 21, 2011. Accepted August 17, 2011. Please include this information when citing this paper: published online October 14, 2011; DOI: 10.3171/2011.8.JNS11618. Supplemental online information: Video: http://mfile.akamai.com/21490/wmv/digitalwbc.download. akamai.com/21492/wm.digitalsource-na-regional/jns11-618_ video.asx (Media Player). http://mfile.akamai.com/21488/mov/digitalwbc.download. akamai.com/21492/qt.digitalsource-global/jns11-618_video.mov (Quicktime). Address correspondence to: Erich Talamoni Fonoff, M.D., Ph.D., Rua Dr. Ovídio Pires de Campos, 785, São Paulo SP, Brazil 01060970. email:
[email protected].
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