Gamma Knife central lateral thalamotomy for the treatment of neuropathic pain

Abstract

OBJECTIVEThe goal of this study was to assess the safety and efficacy of stereotactic central lateral thalamotomy with Gamma Knife radiosurgery in patients with neuropathic pain.METHODSClinical and radiosurgical data were prospectively collected and analyzed in patients with neuropathic pain who underwent Gamma Knife central lateral thalamotomy. The safety and efficacy of the lesioning procedure were evaluated by neurological examination and standardized scales for pain intensity and health-related quality of life. Visual analog scale (VAS) for pain, McGill Pain Questionnaire (MPQ), EuroQol–5 dimensions (EQ-5D), and the 36-Item Short Form Health Survey, version 2 (SF-36v2) were measured during baseline and postoperative follow-up evaluations at 3, 6, 12, 24, and 36 months.RESULTSEight patients with neuropathic pain underwent Gamma Knife central lateral thalamotomy. Four patients suffered from trigeminal deafferentation pain, 2 from brachial plexus injury, 1 from central poststroke facial neuropathic pain, and 1 from postherpetic neuralgia. No lesioning-related adverse effect was recorded during the follow-up periods. All patients had pain reduction following thalamotomy. The mean follow-up time was 24 months. At the last follow-up visits, 5 patients reported ≥ 50% VAS pain reduction. The overall mean VAS pain score was 9.4 (range 8–10) before radiosurgery. After 1 year, the mean VAS pain score decreased significantly, from 9.4 (range 8–10) to 5.5 (mean −41.33%, p = 0.01). MPQ scores significantly decreased (mean −22.18%, p = 0.014). Statistically significant improvements of the SF-36v2 quality of life survey (mean +48.16%, p = 0.012) and EQ-5D (+45.16%, p = 0.012) were observed. At 2 years after radiosurgery, the VAS pain score remained significantly reduced to a mean value of 5.5 (p = 0.027). Statistically significant improvements were also observed for the MPQ (mean −16.05%, p = 0.034); the EQ-5D (mean +35.48%, p = 0.028); and the SF-36v2 (mean +35.84%, p = 0.043). At the last follow-up visits, pain had recurred in 2 patients, who were suffering from central poststroke neuropathic pain and brachial plexus injury, respectively.CONCLUSIONSSafe, nonpharmacological therapies are imperative for the management of refectory chronic pain conditions. The present series demonstrates that Gamma Knife central lateral thalamotomy is safe and potentially effective in the long term for relieving chronic neuropathic pain refractory to pharmacotherapy and for restoring quality of life.

Neuroablative central lateral thalamotomy for chronic neuropathic pain

“…Previous targets have included the central median/parafascicular complex (CM/Pf), the posterior complex (POC), the central lateral nucleus (CL) and the medial pulvinar (PuM) ( 16 – 20 ). Within the medial thalamus, the posterior part of the central lateral thalamus (CLp) regulates the sensory, cognitive, and affective components of chronic neuropathic pain as it serves an intermediary role between the lateral and medial thalamic nuclei ( 5 , 16 ).…”

“…The low interindividual variability of the CLp especially in the anteroposterior axis makes the CLp an ideal surgical target. Small variations can be taken into account through MRI visualization of nearby structures such as the posterior commissure, the habenula, and the stria medullaris ( 5 , 16 , 31 ). In addition, damage to nearby structures such as the MD and PuM result in few neurological deficits and even a partial lesion of the CLp can provide enough de-amplification of the LTS bursts to provide clinical benefit ( 16 ) ( Figure 2 ).…”

“…Early surgical attempts at treating chronic pain aimed to disrupt the pathways that were responsible for the pathogenesis and transmission of pain through ablative procedures. Many regions of the brain were targeted including the thalamus, midbrain, and anterior cingulate cortex ( 5 ). However, due to numerous neurological and sensory complications that arose from surgeries at the pontine and mesencephalic level, stereotactic thalamotomies became the surgery of choice ( 5 , 6 ).…”

“…Many regions of the brain were targeted including the thalamus, midbrain, and anterior cingulate cortex ( 5 ). However, due to numerous neurological and sensory complications that arose from surgeries at the pontine and mesencephalic level, stereotactic thalamotomies became the surgery of choice ( 5 , 6 ). Early thalamotomies primarily targeted the lateral thalamus due to its role in relaying the sensory-discriminative aspect of pain; however, these interventions often resulted in high rates of somatosensory deficits ( 6 – 8 ).…”

Neuropathic pain: Spotlighting anatomy, experimental models, mechanisms, and therapeutic aspects

“…Projections from the spinothalamic tract (see Section 2, Figure 1) to the central lateral nucleus are involved in motivational‐affective responses to pain (reviewed in Sengul & Watson, 2015). A clinical study conducted with a very small cohort indicates that Gamma Knife central lateral thalamotomy may reduce neuropathic pain in patients suffering from trigeminal neuralgia (Franzini et al., 2020). Taken together, these findings could serve as a good starting point for an alternative treatment of neuropathic pain.…”