Gamma Knife surgery targeting the centromedian nucleus of the thalamus for the palliative management of thalamic pain: durable response in stroke-induced thalamic pain syndrome

Hyperactivity of the medial thalamus in patients with photophobia-associated migraine

OBJECTIVE

To examine cerebral functional alterations associated with sensory processing in patients with migraine and constant photophobia.

BACKGROUND

Migraine is a common headache disorder that presents with photophobia in many patients during attacks. Furthermore, some patients with migraine experience constant photophobia, even during headache-free intervals, leading to a compromised quality of life.

METHODS

This prospective, case-control study included 40 patients with migraine (18 male and 22 female) who were recruited at an eye hospital and eye clinic. The patients were divided into two groups: migraine with photophobia group, consisting of 22 patients (10 male and 12 female) with constant photophobia, and migraine without photophobia group, consisting of 18 patients (eight male and 10 female) without constant photophobia. We used 18F-fluorodeoxyglucose and positron emission tomography to compare cerebral glucose metabolism between the two patient groups and 42 healthy participants (16 men and 26 women).

RESULTS

Compared with the healthy group, both the migraine with photophobia and migraine without photophobia groups showed cerebral glucose hypermetabolism in the bilateral thalamus (p < 0.05, family-wise error-corrected). Moreover, the contrast of migraine with photophobia minus migraine without photophobia patients showed glucose hypermetabolism in the bilateral medial thalamus (p < 0.05, family-wise error-corrected).

CONCLUSIONS

The medial thalamus may be associated with the development of continuous photophobia in patients with migraine.

The intralaminar thalamus: a review of its role as a target in functional neurosurgery

The intralaminar thalamus, in particular the centromedian-parafascicular complex, forms a strategic node between ascending information from the spinal cord and brainstem and forebrain circuitry that involves the cerebral cortex and basal ganglia. A large body of evidence shows that this functionally heterogeneous region regulates information transmission in different cortical circuits, and is involved in a variety of functions, including cognition, arousal, consciousness and processing of pain signals. Not surprisingly, the intralaminar thalamus has been a target area for (radio)surgical ablation and deep brain stimulation (DBS) in different neurological and psychiatric disorders. Historically, ablation and stimulation of the intralaminar thalamus have been explored in patients with pain, epilepsy and Tourette syndrome. Moreover, DBS has been used as an experimental treatment for disorders of consciousness and a variety of movement disorders. In this review, we provide a comprehensive analysis of the underlying mechanisms of stimulation and ablation of the intralaminar nuclei, historical clinical evidence, and more recent (experimental) studies in animals and humans to define the present and future role of the intralaminar thalamus as a target in the treatment of neurological and psychiatric disorders.

Case report: Radiofrequency thalamotomy as palliative care for Holmes tremor in a patient with terminal cancer and cardiac pacemaker

Background:

Herein, we present a case report of a patient with Holmes tremor due to thalamic infarction with end-stage pancreatic cancer who underwent successful computed tomography (CT)-guided ventralis intermedius nucleus (Vim) thalamotomy as palliative care.

Case Description:

A 78-year-old man with gradually worsening involuntary movements on the left side of his body 2 years after a right thalamic infarction was referred to our institute. He had a history of chronic atrial fibrillation for which he was implanted with a cardiac pacemaker not compatible with magnetic resonance imaging. He also received adjuvant therapy for pancreatic cancer. As the involuntary movements interfered with his daily life, the patient elected for neurosurgical treatment despite having terminal cancer. Although the prognosis for pancreatic cancer was considered to be more than 6 months at the time of surgery, we performed CT-guided Vim thalamotomy under local anesthesia without pulse generator implantation considering the patient’s general condition. The involuntary movements of the left side of the body reduced following surgery, thus improving his quality of life (QOL). However, 6 months after thalamotomy, the patient died of pancreatic cancer.

Conclusion:

Thalamotomy significantly reduced the involuntary movements immediately after the procedure. Therefore, thalamotomy can be performed under local anesthesia without the use of any device and may contribute to the improvement of QOL in terminal patients.

Medial thalamotomy using stereotactic radiosurgery for intractable pain: a systematic review

Medial thalamotomy using stereotactic radiosurgery (SRS) is a potential treatment for intractable pain. However, the ideal treatment parameters and expected outcomes from this procedure remain unclear. The aim of this systematic review is to provide further insights on medial thalamotomy using SRS, specifically for intractable pain. A systematic review was performed to identify all clinical articles discussing medial thalamotomy using SRS for intractable pain. Only studies in which SRS was used to target the medial thalamus for pain were included. For centers with multiple publications, care was taken to avoid recounting individual patients. The literature review revealed six studies describing outcomes of medial thalamotomy using SRS for a total of 125 patients (118 included in the outcome analysis). Fifty-two patients were treated for cancer pain across three studies, whereas five studies included 73 patients who were treated for nonmalignant pain. The individual studies demonstrated initial meaningful pain reduction in 43.3-100% of patients, with an aggregate initial meaningful pain reduction in 65 patients (55%) following SRS medial thalamotomy. This effect persisted in 45 patients (38%) at the last follow-up. Adverse events were observed in six patients (5%), which were related to radiation in five patients (4%). Medial thalamotomy using SRS is effective for select patients with treatment-resistant pain and is remarkably safe when modern radiation delivery platforms are used. More posteriorly placed lesions within the medial thalamus were associated with better pain relief. More studies are warranted to shed light on differences in patient responses.

Stereotactic Radiosurgery Hypophysectomy for Palliative Treatment of Refractory Cancer Pain: A Historical Review and Update

Medically refractory pain in those with advanced cancer significantly reduces one's quality of life. Therefore, palliative interventions to mitigate cancer pain and reduce opioid requirements are necessary to reduce patient suffering and opioid-induced side effects. Hypophysectomy, a largely forgotten pain procedure with several technical variations, has been repeatedly studied in small series with encouraging results, though historically has been fraught with complications. As a result, the minimally invasive and more tolerable stereotactic radiosurgery (SRS) hypophysectomy has resurfaced as a possible treatment for cancer-related pain. While the mechanism of pain relief is not entirely understood, the hypothalamohypophyseal axis appears to play an essential role in pain perception and transmission and involves C fiber signal processing and downstream modulation of the brainstem and spinal cord via the hypothalamus. This review highlights the role of hypophysectomy in alleviating advanced cancer pain, both in hormonal and nonhormonal malignancy and the current mechanistic understanding of pain relief for the three primary hypophysectomy modalities used historically: surgical and chemical adenolysis, as well as the more recent, SRS hypophysectomy. Given the lack of high-quality evidence for stereotactic radiosurgery hypophysectomy, there is a need for further rigorous and prospective clinical studies despite its ideal and noninvasive approach.

Stereotactic Gamma Ray Radiosurgery to the Centromedian and Parafascicular Complex of the Thalamus for Trigeminal Neuralgia and Other Complex Pain Syndromes

Introduction We report our initial series of patients treated with radiosurgery to the Centromedian (CM) and Parafascicular (Pfc) Complex (CM-Pf) of the contralateral thalamus mainly for trigeminal neuralgia that had failed most known forms of conventional treatments. The coordinates were co-registered to a three-dimensional atlas of the thalamus in order to have a better comprehension of isodose curves distribution. Methods A fully automated rotating gamma ray unit was used to deliver a high dose of radiation (140 Gy) using a 4-mm collimator to the CM-Pf of the contralateral thalamus in 14 patients suffering from refractory trigeminal pain and other complex pain syndromes. The best stereotactic coordinates were plotted in a thalamic three-dimensional atlas space along with isodose curves corresponding to 50% of the dose prescription and the dose gradient. Results From November 2016 to July 2019, 14 patients experiencing severe forms of different pain syndromes were treated, and 10 were eligible for follow-up evaluation. Pain deriving from trigeminal neuralgia was present in the majority (80%) of patients and from other complex pain syndromes in the rest (20%). Median follow-up was 384 days (range: 30-994). The Visual Analogue Scale (VAS) score before treatment was 9 (range: 7-10) and standardized to 10. Before treatment, all the patients had a Barrow Neurological Institute Pain Scale (BNI) of 5 (V). The median years suffering from pain was 4.5 years (range: 1-15), the number of procedures including radiosurgery to the trigeminal nerve before thalamotomy was four (range: 1-10). Most patients (90%) reported some form of relief, the average VAS at the time of response was 3.5 (range: 0-9), and the average time to response was 67.3 days (range: 2-210). The neuromodulation effect of radiation was seen in 60% of patients. The average BNI score at response was 2.7 (range: 1-5). The final VAS score at last follow-up was 5.5 (range: 0-10) in six patients. In four patients (40%), the procedure had failed with a final BNI of IV, and V, three patients (30%) had excellent response (BNI of I), and three patients (30%) had worthwhile results with BNI of IIIa and IIIb. The total success rate (BNI of I to IIIb) was 60%, and the number of patients experiencing more than 50% of pain reduction at final follow-up was five (50%). Excluding both patients that were treated for pain outside of trigeminal neuralgia, 75% of the patients responded. The best coordinates on average were X: 5.5 mm from the thalamic border, Y: 3.7 mm anterior to the posterior commissure, and Z: 3.7 mm from the intercomissural line. There were no complications to report. Conclusion Radiosurgery to the CM-Pf of the thalamus was demonstrated to be a safe and relatively effective alternative to treat refractory trigeminal neuralgia. Further studies are needed to optimize target dimensions based on the three-dimensional studies of isodose curves as well as coordinates. Longer follow-up is necessary to evaluate recurrence rates that could not be reached.

Stereotactic Radiosurgery for the Treatment of Chronic Intractable Pain: A Systematic Review

BACKGROUND

Since the advent of neuromodulation, the role and efficacy of stereotactic radiosurgery (SRS) for chronic pain has not been carefully scrutinized.

OBJECTIVE

To perform a systematic review to evaluate the clinical efficacy, both short- and long-term, of SRS for the treatment of chronic intractable pain.

METHODS

A systematic search in PubMed, Web of Science, and PsycINFO was performed using keywords and controlled vocabulary. The search included peer-reviewed articles reporting clinical outcomes of SRS for chronic pain with a minimum 3-mo follow-up for nonmalignant and 1 mo for malignant pain.

RESULTS

Six articles (113 patients) were evaluated on the basis of radiation target (thalamus vs pituitary) and pain etiology (malignant vs nonmalignant). Across studies, at least 35% of patients were reported to have lasting significant pain relief. By cohort, clinical success was achieved in 51% of pituitary SRS, at least 23% of thalamic SRS, 39% of nonmalignant, and at least 33% of malignant pain patients. Adverse events were noted in 21% of patients; the majority related to hormonal deficits from pituitary SRS.

CONCLUSION

Despite decreased utilization, SRS is effective for select patients with chronic pain and is associated with an acceptable complication rate. Pituitary SRS is superior in patients with cancer-related pain (87% success), while thalamic SRS is superior in patients with nonmalignant pain (65% success). Because reports of SRS for pain largely stem from a period before the common use of neuromodulatory and intrathecal therapies, the efficacy in patients who fail such therapies remains unclear and requires further characterization.

Dejerine-Roussy syndrome from thalamic metastasis treated with stereotactic radiosurgery

Dejerine-Roussy syndrome (central thalamic pain) is associated with damage to the ventral posterior sensory nuclei of the thalamus. We report a patient with breast cancer who developed contralateral hemibody paresthesias and dysesthesias. MR imaging revealed limited volume intracranial metastatic disease including a right posterior thalamic lesion. Stereotactic radiosurgery was utilized to selectively treat the lesion while preserving the remaining thalamus. Two months following treatment, the patient reported vastly improved to complete resolution of her sensory symptoms. This is the first reported case of thalamic tumor directed radiosurgical treatment leading to resolution of central neuropathic pain.