Human amygdala activation during rapid eye movements of rapid eye movement sleep: an intracranial study.

The amygdaloid complex plays a crucial role in processing emotional signals and in the formation of emotional memories. Neuroimaging studies have shown human amygdala activation during rapid eye movement sleep (REM). Stereotactically implanted electrodes for presurgical evaluation in epileptic patients provide a unique opportunity to directly record amygdala activity. The present study analysed amygdala activity associated with REM sleep eye movements on the millisecond scale. We propose that phasic activation associated with rapid eye movements may provide the amygdala with endogenous excitation during REM sleep. Standard polysomnography and stereo-electroencephalograph (SEEG) were recorded simultaneously during spontaneous sleep in the left amygdala of four patients. Time-frequency analysis and absolute power of gamma activity were obtained for 250 ms time windows preceding and following eye movement onset in REM sleep, and in spontaneous waking eye movements in the dark. Absolute power of the 44-48 Hz band increased significantly during the 250 ms time window after REM sleep rapid eye movements onset, but not during waking eye movements. Transient activation of the amygdala provides physiological support for the proposed participation of the amygdala in emotional expression, in the emotional content of dreams and for the reactivation and consolidation of emotional memories during REM sleep, as well as for next-day emotional regulation, and its possible role in the bidirectional interaction between REM sleep and such sleep disorders as nightmares, anxiety and post-traumatic sleep disorder. These results provide unique, direct evidence of increased activation of the human amygdala time-locked to REM sleep rapid eye movements.

New Horizons in Temporal Lobe Seizure Control.

SUMMARY: In patients with mesial temporal lobe epilepsy, high-frequency, low-amplitude electrical stimulation (ES) was applied during 3 weeks through contacts of intracranial electrodes that defined the epileptogenic zone. This subacute ES induced cessation of spontaneous seizures, decreased the number of EEG interictal spikes, caused a 10-fold increase in threshold to induce postdischarges, and showed a profound decrease in regional blood flow of the stimulated area in SPECT studies. Autoradiography analysis of surgical specimens from these patients demonstrated increased expression of benzodiazepine receptors and in gamma-aminobutyric acid content, particularly in the parahippocampal cortex. These observations provided evidence of a gamma-aminobutyric acid-mediated antiepileptic effect induced by ES. Several reports of long-term hippocampal ES through internalized neurostimulators have confirmed the antiepileptic effect on mesial temporal lobe-initiated seizures, with preservation of neuropsychological performance, in particular memory functions. The experience of the authors is that the response is optimal in patients without hippocampal sclerosis evidenced by MRI, whereas it is less significant and delayed in patients with hippocampal sclerosis. Other studies reported the best result stimulating through the contacts in the subiculum, the transition between the hippocampus and parahippocampal cortex, that usually escapes to the hippocampal sclerosis. Currently, the effect of ES directed at the subiculum and the parahippocampal cortex in patients with hippocampal sclerosis is under investigation.

Electrical activity of the human amygdala during all-night sleep and wakefulness.

OBJECTIVE: The aim of the present work was to characterize the dynamics of the human amygdala across the different sleep stages and during wakefulness. METHODS: Simultaneous intracranial electrical recordings of the amygdala, hippocampus, and scalp electroencephalography during spontaneous sleep polysomnography in four patients suffering from epilepsy were analyzed. RESULTS: Power spectrum of the amygdala revealed no differences between rapid eye movement (REM) and wakefulness for all frequencies except higher power at 9 Hz during wakefulness and some low Gamma frequencies. Conversely, higher power was observed in non-REM (NREM) sleep than wakefulness for Delta, Theta and Sigma. CONCLUSIONS: Our results showed similar activity in the amygdala between wakefulness and REM sleep suggesting that the amygdala is as active in REM as during wakefulness. The higher power in Sigma frequencies during NREM sleep suggests that amygdala slow activity may play a significant role during NREM in concurrence with hippocampal activity. SIGNIFICANCE: While studies have described the metabolic activity of the human amygdala during sleep, our results show the corresponding electrical pattern during the whole night, pointing out an increase of slow activity during NREM sleep that might be subjected to similar influences as other subcortical brain structures, such as the hippocampus.

Coupled obturator neurotomies and lidocaine intrathecal infusion to treat bilateral adductor spasticity and drug-refractory pain.

Spastic diplegia is present in three-fourths of children with cerebral palsy, interfering with gait and frequently accompanied by severe pain. The authors report the case of a 28-year-old woman with history of perinatal hypoxia, who presented with cerebral palsy and severe spastic diplegia (Ashworth Scale Score 4, Tardieu Scale Score 5) and was confined to a wheelchair. She complained of pain in the left hip and knee with mixed neuropathic and somatic components. She consistently rated pain intensity as 10 of 10 on a visual analog scale, and her symptoms were resistant to multiple treatments. The patient underwent selective bilateral adductor myotomies and the implantation of an infusion pump for intrathecal lidocaine application. Postoperative control of pain and spasticity was dramatic (scores of 0 on the Ashworth, Tardieu, and visual analog scales) and persisted throughout a follow-up period of 36 months. This is the first report in the literature of combined selective neurotomies for the treatment of spasticity and chronic lidocaine subarachnoid infusion to treat associated pain. This therapy could represent an alternative to treat spasticity associated with neuropathic and somatic pain.

Motor cortex electrical stimulation applied to patients with complex regional pain syndrome.

Motor cortex stimulation (MCS) is useful to treat patients with neuropathic pain syndromes, unresponsive to medical treatment. Complex regional pain syndrome (CRPS) is a segmentary disease treated successfully by spinal cord stimulation (SCS). However, CRPS often affects large body segments difficult to cover by SCS. This study analyzed the MCS efficacy in patients with CRPS affecting them. Five patients with CRPS of different etiologies underwent a small craniotomy for unilateral 20-grid-contact implantation on MC, guided by craniometric landmarks. Neurophysiological and clinical tests were performed to identify the contacts position and the best analgesic responses to MCS. The grid was replaced by a definitive 4-contacts-electrode connected to an internalized system. Pain was evaluated by international scales. Changes in sympathetic symptoms, including temperature, perspiration, color and swelling were evaluated. Pre-operative and post-operative monthly evaluations were performed during one year. A double-blind maneuver was introduced assigning two groups. One had stimulators turned OFF from day 30-60 and the other from day 60-90. Four patients showed important decrease in pain, sensory and sympathetic changes during the therapeutic trial, while one patient did not have any improvement and was rejected for implantation. VAS and McGill pain scales diminished significantly (p<0.01) throughout the follow-up, accompanied by disappearance of the sensory (allodynea and hyperalgesia) and sympathetic signs. MCS is effective not only to treat pain, but also improve the sympathetic changes in CPRS. Mechanism of action is actually unclear, but seems to involve sensory input at the level of the spinal cord.

Bilateral electrical stimulation of prelemniscal radiations in the treatment of advanced Parkinson's disease.

OBJECTIVE: Tremor and rigidity have been efficiently controlled by electrical stimulation of contralateral prelemniscal radiations (Raprl) in patients with unilateral Parkinson's disease. The present study determines the effect of bilateral Raprl electrical stimulation in a group of patients with severe bilateral tremor, rigidity, and bradykinesia. METHODS: Five patients with Parkinson's disease (Hoehn and Yahr scale, Stage V) underwent bilateral stereotactic electrode implantation. Postoperative magnetic resonance imaging studies confirmed their position. Bipolar chronic electrical stimulation was performed through contiguous contacts of each electrode, which were selected by means of a screening test that explored multiple combinations. Preoperative and 3-, 6-, 9-, and 12-month postoperative evaluations were performed using international rating scales. Postoperative evaluations were performed with 24 hours off medication-on stimulation. RESULTS: Contralateral tremor and rigidity were significantly decreased by simple insertion of electrodes in Raprl and returned hours to days later. Contacts for chronic stimulation were located in the area between the red and subthalamic nuclei, including Raprl, zona incerta, and substantia Q. Efficient stimulation had at least one contact in Raprl and in four cases, both contacts were only in Raprl. Stimulation parameters were 90 to 130 Hz, 90 to 330 mus, and 1.5 to 3.5 V. Unified Parkinson's Disease Rating Scale (motor, Part III) scores decreased 65% (P < 0.001), with improvements of 90% in tremor (P < 0.001), 94% in rigidity (P < 0.001), 75% in bradykinesia (P < 0.001), 40% in gait, and 35% in postural stability (P < 0.05) at 1 year. CONCLUSION: Raprl electrical stimulation is safe and efficient to treat patients with the Parkinson's disease symptomatic triad. By use of Raprl stereotactic coordinates, electrodes were placed behind the subthalamic nucleus.