Surgical control of the human thalamocortical dysrhythmia: I. Central lateral thalamotomy in neurogenic pain

Abstract

Reactualization of the medial thalamotomy, performed since the fifties in cases of neurogenic pain, has been guided by the discovery of low threshold calcium spike bursts at frequencies in the delta-theta range in the posterior part of the central lateral (CL) nucleus. This thalamic rhythmicity is transmitted to the cortex through thalamocortical resonant properties, giving rise to the thalamocortical dysrhythmia, proposed to be the mechanism of neurogenic pain as well as other central nervous system (CNS) dysfunctions. Magnetic resonance-and microelectrode-guided stereotactic CL thalamotomy was implemented in 96 patients suffering from chronic therapy-resistant peripheral or central neurogenic pain (mean age: 56 ± 15 years; pain duration before surgery: 7.5 ± 8 years). At a mean follow-up of 3 years, 9 months ± 2 years, 9 months, 53% of the patients benefited from a relief superior to 50% (complete relief in 18.7%). Further analysis of the results demonstrated a significant difference between patients suffering from intermittent as compared with continuous pain. Patients with continuous pain showed only a mean relief of 20.4 ± 25.8% in contrast to the 66 ± 39.2% obtained for patients with intermittent (episodic or paroxysmal) pain manifestations. This was confirmed by the pre-and postoperative visual analogue scale scores showing a significant decrease (59.2%) only in the patient group with intermittent pain. Allodynia was suppressed in 57.3% of the patients. Parameters such as the preoperative pain duration or the site of the causal lesion did not affect the surgical outcome. In 28 patients suffering from unilateral continuous pain, the addition of an ipsilateral CL thalamotomy provided a further significant pain relief. A suppression of drug intake was observed in 31.6% of the patients. Complications occurred in 11.5% of the patients and led to a long term significant disability in only one case. In conclusion, CL thalamotomy is a safe neurosurgical option for neurogenic pain, especially for patients suffering from intermittent pain or allodynia. Its limitation in cases of continuous pain indicates the necessity to explore other stereotactic targets outside of the medial thalamus.

Transcranial magnetic resonance imaging–guided focused ultrasound: noninvasive central lateral thalamotomy for chronic neuropathic pain

“…26 The clinical results presented here support our long experience with radiofrequency CLT treatment for chronic therapy-resistant neuropathic pain. 19,20 The patients in this series showed a typical mean group pain relief profile across time, from 71% at 2 days after treatment to 49% at 3 months and 57% at 1 year after treatment. The VAS improvement was similar at 3 months (42%) and at 1 year (41%).…”

“…A bilateral CLT is, in general, necessary, and it is as sparing of brain functions as a unilateral one. 19 In 4 patients, the tcMRgFUS treatment complemented a previously performed radiofrequency treatment. The CLT was performed unilaterally for the following reasons: complement to radiofrequency treatment (2 patients), appearance of bleeding (1 patient; see Clinical Results), immediate 100% pain relief after treatment of the first side (1 patient), and intolerance of a longer intervention time (1 patient).…”

“…The mean spectral band power was calculated from 1-48 Hz. Spectral bands were defined as follows: delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-13 Hz), and beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). (Note that the superior spectral band limit is included only in the next higher band.)…”

“…Based on our long-term clinical experience in functional neurosurgery for neuropathic (or neurogenic) pain with radiofrequency stereotactic interventions in the medial thalamus, 17,19,20 and after preclinical studies with phantoms, biological tissues, and ex vivo human head preparations, we adapted our interventional procedure to perform CLTs in patients suffering from chronic neuropathic pain using the tcMRgFUS technology. The study was approved by the ethics committee of Zurich University and the state of Zurich (Kantonale Ethikkommission des Kantons Zürich).…”

Cross-modal plasticity in the human thalamus: evidence from intraoperative macrostimulations

“…The thalamus has been from the beginning an important target for neurogenic pain and motor disorders, and both medial and lateral nuclei were explored (Sano et al, 1966;Cooper et al 1969;Goldmann et al 1992;Gybels et al 1993;Yamashiro and Tasker 1994;Burchiel 1995;Velasco et al 1995;Benabid et al 1996;Abosch and Lozano 2003). In the medial thalamus, the intralaminar nuclei, including the central lateral and centre médian nuclei, were chosen in neurogenic pain for their connections with the medial spinothalamic tract, and more generally for their recruiting properties through "diffuse" projections to the cortex (Morison and Dempsey 1942;Mehler 1966Mehler , 1974Sano et al 1966;Jones and Leavitt 1974;Macchi and Bentivoglio 1986;Jeanmonod et al 1996Jeanmonod et al , 2001a. With recent reappraisal of the anatomical boundaries of the CL, particularly its posterior extension (Hirai and Jones 1989;Morel et al 1997, Morel 2007) and on the basis of its extensive projections to the cortex and thalamic reticular nucleus, this nucleus has been re-updated as a neurosurgical target, alone or in combination with others, for surgical interventions in several functional disorders (Jeanmonod et al 1996(Jeanmonod et al , 2001a(Jeanmonod et al ,b, 2003.…”