J. Maarrawi

Brain opioid receptor density predicts motor cortex stimulation efficacy for chronic pain.

Summary Brain 11C‐diprenorphine positron emission tomography scans help clinicians to select the best candidates for motor cortex stimulation among patients with severe refractory neuropathic pain. Abstract The clinical effects of motor cortex stimulation (MCS) for neuropathic pain (NP) is thought to be mediated primarily by the secretion of endogenous opioids in humans and in animal models. Because opioid receptor density is itself decreased in patients with NP, we investigated whether the magnitude and distribution of the remaining opioid receptors in patients with NP could be biological predictors of the pain‐relieving effects of MCS. Using 11C‐diprenorphine positron emission tomography scans, opioid receptor availability was assessed in 15 patients suffering refractory NP, who subsequently received chronically implanted MCS. All patients underwent 2 preoperative baseline scans at 2‐wk intervals and were clinically assessed after 7 mo of chronic MCS. The levels of preoperative opioid‐binding in the insula, thalamus, periaqueductal gray, anterior cingulate, and orbitofrontal cortex were significantly and positively correlated with postoperative pain relief at 7 mo. Patients with receptor density values below the lower limits in age‐matched controls in the thalamus, periaqueductal gray and contralateral insula were the least likely to benefit from MCS. Opioid‐receptor availability as shown in preoperative positron emission tomography scans appears to be related to the efficacy of MCS in NP and may help clinicians to select the candidates most likely to benefit from this procedure.

Impact of the lunar cycle on the incidence of intracranial aneurysm rupture: Myth or reality?

OBJECTIVE To analyze the impact of the lunar cycle and season on the incidence of aneurysmal subarachnoid hemorrhage (SAH). PATIENTS AND METHODS The medical records of 111 patients who were admitted over a 5-year period to our department because of aneurysmal SAH were retrospectively reviewed. The date of aneurysm rupture was matched with the corresponding season and moon phase. RESULTS An incidence peak for aneurysm rupture (28 patients) was seen during the phase of new moon, which was statistically significant (p < 0.001). In contrast, no seasonal variation in the incidence of SAH was observed. CONCLUSION The lunar cycle seems to affect the incidence of intracranial aneurysm rupture, with the new moon being associated with an increased risk of aneurysmal SAH.

Stereotactic functional mapping of the cat motor cortex

Epidural motor cortex stimulation is an increasingly used method to control refractory neuropathic pain although its mechanisms of action remain poorly understood. Animal models are currently developed that allow reproducing the conditions of this neurosurgical approach and clarifying its mechanisms. In this study we validate a new stereotactic functional map of the cat motor cortex carried out in epidural conditions, thus allowing future experimentations that closely mimic the technique used in humans.

Functional exploration for neuropathic pain

Neuropathic pain (NP) may become refractory to conservative medical management, necessitating neurosurgical procedures in carefully selected cases. In this context, the functional neurosurgeon must have suitable knowledge of the disease he or she intends to treat, especially its pathophysiology. This latter factor has been studied thanks to advances in the functional exploration of NP, which will be detailed in this review. The study of the flexion reflex is a useful tool for clinical and pharmacological pain assessment and for exploring the mechanisms of pain at multiple levels. The main use of evoked potentials is to confirm clinical, or detect subclinical, dysfunction in peripheral and central somato-sensory pain pathways. LEP and SEP techniques are especially useful when used in combination, allowing the exploration of both pain and somato-sensory pathways. PET scans and fMRI documented rCBF increases to noxious stimuli. In patients with chronic NP, a decreased resting rCBF is observed in the contralateral thalamus, which may be reversed using analgesic procedures. Abnormal pain evoked by innocuous stimuli (allodynia) has been associated with amplification of the thalamic, insular and SII responses, concomitant to a paradoxical CBF decrease in ACC. Multiple PET studies showed that endogenous opioid secretion is very likely to occur as a reaction to pain. In addition, brain opioid receptors (OR) remain relatively untouched in peripheral NP, while a loss of ORs is most likely to occur in central NP, within the medial nociceptive pathways. PET receptor studies have also proved that antalgic Motor Cortex Stimulation (MCS), indicated in severe refractory NP, induces endogenous opioid secretion in key areas of the endogenous opioid system, which may explain one of the mechanisms of action of this procedure, since the secretion is proportional to the analgesic effect.

Antithrombotic Medication Use and Misuse Among Patients with Intracranial Hemorrhage: A 16-Year, Lebanese, Single-Center Experience

OBJECTIVE/BACKGROUND The use of antithrombotic medication (ATM) frequently is reported in patients with intracranial hemorrhage (ICH) and is associated with increased mortality. Unfortunately, ATMs sometimes are prescribed and/or used inappropriately. We sought to determine the rate of ATM misprescription/misuse among patients with ICH in a single-center retrospective study. METHODS All patients admitted with ATM-related ICH in 1998-2014 were included. Charts were reviewed and demographic, clinical, and radiologic variables were recorded. The type of ATM, dose, and duration of treatment were analyzed critically. The adequacy of ATM prescription/use was assessed in light of the recommendations and guidelines of the American Heart Association, American Stroke Association, and French National Authority for Health, in effect at the time of admission. RESULTS A total of 106 patients with mean age 68 years were identified. Aspirin (53.8%) was the most commonly used drug, followed by oral anticoagulants (31.1%) and clopidogrel (22.6%). In only 80 patients (75.5%), the use of ATM was in line with contemporary guidelines. In the remaining 26 (24.5%), the use of ATMs was inappropriate, including bad drug combination, wrong dose, poor indication, wrong drug class, and/or incorrect treatment duration. CONCLUSIONS In this Lebanese cohort of patients with ICH, the 24.5% rate of ATM misprescription and/or misuse is highly alarming and the origin of this problem is likely multifactorial. Immediate measures should be undertaken, and efforts should be focused on regaining tight control of ATM prescription and fulfillment, ensuring good patient education, and offering more vigilant oversight on physician licensure.