Isolated Subthalamic Nucleus Spikes: Are They Epileptogenic?
Abstract number :
1.134
Submission category :
Year :
2001
Submission ID :
2116
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
D.S. Dinner, M.D., Neurology, The Cleveland Clinic Foundation, Cleveland, OH; S.B. Neme, MD, Neurology, The Cleveland Clinic Foundation, Cleveland, OH; E.B. Montgomery, MD, Neurology, The Cleveland Clinic Foundation, Cleveland, OH; A. Rezai, MD, Neurosurg
RATIONALE: Deep brain stimulation of the thalamus and subthalamic nucleus (STN) for the treatment of intractable epilepsy is undergoing trial in experimental protocols. We have recently reported that scalp- recorded sharp waves are invariably associated with STN spikes in intractable focal epilepsy. In addition in these patients we recorded spikes restricted to the STN electrodes without any scalp-recorded discharges (isolated STN spikes). In this study we report the effect of sleep on the isolated STN spikes.
METHODS: Four patients (3 males, 1 female) ranging in age form 19 to 54 years were included. Depth electrodes were implanted bilaterally in the STN by stereotaxic technique. Each electrode had 4 contacts 1.27 mm in diameter separated by 1.5 mm. Comparative analysis of the frequency of isolated STN spikes in relation to awake and sleep states was performed.
RESULTS: Isolated STN spikes were recorded in 3 patients with focal epilepsy and one patient with Parkinson[scquote]s disease (PD). Isolated STN spikes had a duration ranging from 39-94 msec, and amplitude of 97-278 uV. In the three epilepsy patients the spike frequency awake was 1 every 2-5 minutes. There was an increase in spike frequency of 3-6 times in stage I NREM sleep and 7-11 times in stage II NREM sleep. In REM sleep there was a decrease in the spike frequency to that of the awake state.
In the PD patient no spikes were recorded in the awake state, but spikes appeared during stage I NREM sleep at a frequency of 1 per minute independantly at the left and right STN electrodes.
CONCLUSIONS: The infrequent isolated STN spikes recorded in the PD patient support the possibility of these spikes being secondary to neuronal injury or representing a physiologic activity. The high frequency of isolated STN spikes in the epilepsy patients also may be secondary to insertional injury affecting the STN neurons, which are hyperexcitable due to a diffuse neuronal hyperexcitability that presumably occurs in epilepsy. Alternatively the isolated STN spikes may represent cortical spikes that are not seen at the scalp.