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Update on surgery for pain
Trigeminal neuralgia: surgery vs. medical treatment In the January issue of Pain, Zakrzewska and Pasalos report a long-term cohort study comparing medical and surgical management of trigeminal neuralgia. They followed 15 patients for 13 years and concluded that surgery had better outcomes in all patients who had it, comparing to even high regimens of oxcarbazepine (Trileptal). The authors analyze the probability of remaining pain-free after medical and surgical treatment and find significant difference between these modalities. Based on their findings, the authors state that "patients may … benefit from having surgery earlier rather than later in the disease process in order to improve quality of life, freedom from medication and the need for regular follow up." Since this is perhaps the first study that directly compares medical and surgical treatment, I think it would be important for neurosurgeons in their argument for earlier surgical intervention. Motor cortex stimulation for pain or spasticity A study from the Toronto group on motor cortex stimulation mechanisms is scheduled to appear in Clinical Neurophysiology (and may be accessed online at the journal web-site). Hanajima and coauthors evaluated effects of acute stimulation through electrode contacts inserted into the subdural space in patients with chronic pain or multiple system atrophy-related rigidity. They analyzed impedance values, various stimulation settings, paired stimulation effects and strength-duration curves while recording surface EMG from contralateral arm muscles. The conclusion of the study is that stimulation of the subdural electrodes placed over the motor cortex appears to activate low thresholds neural elements, probably myelinated axons, which in turn may activate corticospinal neurons and inhibitory neurons in the cortex producing detectable effects on motoneurons. Combining this information with findings from functional and biochemical imaging may help in understanding exact effects of chronic motor cortex stimulation in patients with pain and movement disorders.
Konstantin Slavin, MD |