Arun Angelo Patil

Stereotactic volumetric radiofrequency lesioning of intracranial structures for control of intractable seizures.

Computed tomography (CT) scans provide three-dimensional information about intracranial structures, which can be used to place stereotactically guided radiofrequency (RF) lesions and destroy a targeted volume of tissue. This technique was used for lesioning of the corpus callosum (CC) or the amygdala-hippocampus complex (AHC) in 9 patients with intractable seizures. The procedures were monitored by intraoperative CT scans. Lesions were made in the AHC in 7 patients and the CC in 2 patients. In addition, multiple subpial transection (MST) was performed in 6 patients. The longest follow-up is 29 months with a median of 19 months. Five patients (56%) are free of seizures, 3 patients (33%) have greater than 90% reduction in seizure activity and 1 patient (11%) has greater than 50% but at most 90% reduction in seizure activity. There were no complications except for temporary hemiparesis following MST in 1 patient. The results suggest that stereotactic volumetric RF lesioning of the AHC and the CC may be safe and effective in controlling intractable seizures.

Stimulation of the nervous system for the management of seizures: current and future developments.

Vagal nerve stimulation (VNS) for the treatment of refractory epilepsy appears to have started from the theory that since VNS can alter the EEG, it may influence epilepsy. It proved effective in several models of epilepsy and was then tried in short-term, open-label and double-blind trials, leading to approval in Canada, Europe and the US. Follow-up observations in these patients demonstrated continued improvement in seizure control for up to 2 years. Close to 50% of treated patients have achieved at least a 50% reduction in seizure frequency. This therapy was also useful as rescue therapy for ongoing seizures in some patients; many patients are more alert. The initial trials were completed in patients ≥12 years of age with refractory partial seizures. Subsequently, similar benefits were shown in patients with tuberous sclerosis complex, Lennox-Gastaut syndrome, hypotha-lamic hamartomas and primary generalised seizures.Implanting the generator and leads is technically easy, and complications are few. The method of action is largely unknown, although VNS appears to alter metabolic activity in specific brain nuclei. Considering that improvement in mood is frequently found in patients using VNS, it has undergone trials in patients with depression. Other illnesses deserving exploration with this unusual therapy are Alzheimer’s disease and autism.Some aspects of VNS have proven disappointing. Although patients have fewer seizures, the number of antiepileptic drugs they take is not significantly reduced. In addition, there is no way to accurately predict the end of life of the generator. Optimal stimulation parameters, if they exist, are unknown.Deep brain stimulation is a new method for controlling medically refractory seizures. It is based on the observation that thalamic stimulation can influence the EEG over a wide area. Several thalamic nuclei have been the object of stimulation in different groups of patients. Intraoperative brain imaging is essential for electrode placement. The procedure is done under local anaesthesia. Experience with this therapy is currently limited, but growing.

Single incision for implanting a vagal nerve stimulator system (vnss):: Technical note

BACKGROUND A technique for implanting the vagal nerve stimulator system through a single incision is described. METHOD A transverse incision is made in the lower part of the neck. Subcutaneous (s.c.) dissection is then done over the clavicle into the infraclavicular area to create a pocket. The vagus nerve is exposed and the electrodes are wrapped around it through the neck incision. The distal ends of the lead are connected to the pulse generator, and latter is then placed in the infraclavicular pocket through the neck incision. RESULTS Thirty-eight implants were conducted with this technique. The pulse generator could be implanted and anchored to the underlying tissue without any difficulty. Except for wound infections in two patients there was no other complication. CONCLUSION A single incision is an alternate to the double incision procedure. This procedure can be performed safely.

Surgical treatment of intractable seizures with multilobar or bihemispheric seizure foci (MLBHSF)

BACKGROUND Patients with multilobar or bihemispheric seizure foci (MLBHSF) are generally not considered candidates for major resective surgery because of the high risk of complications. A combination of relatively less invasive surgical procedures were used to treat 19 patients with intractable seizures with MLBHSF. METHODS Epileptogenic areas were identified via standard techniques. Locations of the seizure foci were in two lobes of a hemisphere in 11 patients, three lobes of a hemisphere in four patients, four lobes of a hemisphere in one patient, and both hemispheres in three patients. All 19 patients had multiple subpial transections; in addition, seven patients had small topectomies and nine patients had amygdala hippocampotomies. RESULTS The longest follow-up is 54 months and the median for follow-up is 33 months. Nine patients (47%) are either free of seizures or have only rare seizures; eight patients (41%) have greater than 90% reduction in seizure frequency; one patient (6%) has complete cessation of myoclonic seizures and secondary generalization, and greater than 50% reduction in partial complex seizures; and one patient (6%) has greater than 50% reduction in seizure frequency. There were no permanent operative complications. CONCLUSION Though the follow-up is relatively short and the number of patients is small, these results are encouraging, because the majority of patients in this group were poor surgical candidates.

Compute tomography-oriented stereotactic system.

A new and simple computed tomography (CT)-oriented stereotactic system that uses the basic principle of working in the CT plane of the target is described. The system consists of a movably mounted frame carrying an adjustable probe holder capable of sliding along the length of the frame and being inclined to any desired angle, together with an independently mounted head fixed system. The movably mounted frame and the sliding probe holder are adjusted in the CT plane of the target. The angle and the distance to which the probe holder should be adjusted for accurate probing can be obtained from a single scan image. The system can be used in any total body scanner with standard features. No special computer programming is necessary, and no calculations are needed. The operation of the system is described wit illustrative cases.

Long term follow-up after multiple hippocampal transection (MHT).

PURPOSE Multiple hippocampal transection (MHT) is a new surgical procedure which disrupts seizure propagation within the hippocampus without impairing verbal memory or the loss of stem cells. Since there are very few papers on this procedure, the authors are presenting their long term results to increase the database on this procedure. METHOD Long term outcome in 15 consecutive patients who had MHT for unlilateral temporal lobe epilepsy, had intra-operative electro-corticography (ECoG) and have a minimum follow-up of at least 2 years is presented. The male/female ratio is 2/1; follow-up is 24-60 months (median of 41 months); and ages between 25 and 60 years. All patients had multiple subpial transection (MST) on the neocortex and MHT on the hippocampus. Amygdalectomy was done if seizure focus was present in the amygdala (10 patients). Temporal tip (1.5-2.5 cm in length) was resected (11 patients) when it was resistant to MST, based on intraoperative EEG recordings. RESULTS There was no permanent neurological complication. Fourteen patients (94.7%) are seizure free (Engels Class I) and 1 (5.3%) has rare seizures (Class II). Neuropsychological studies showed that verbal memory was preserved. CONCLUSION The results show that the seizure outcome with MHT is equal or better than those reported with standard temporal lobectomy. Furthermore verbal memory is preserved. The study also shows that intraoperative ECoG is important in order to conclude adequacy of the procedure. Based on the result of this study the authors feel that this procedure needs to be persued as an alternate to hippocampectomy.

Cortically evoked motor action potential in spinal cord injury research.

Somatosensory evoked potentials (SEPs) have been used extensively in the neurophysiological assessment of spinal cord integrity. However, SEPs mainly reflect the function of the dorsal column. In an effort to find a reliable method of assessing the integrity of the motor tracts for experimental purposes, we studied cortically evoked motor action potentials (CEMAPs). Twenty white rats used were anesthetized with ketamine, and extradural cortical stimulation was carried out through a parasagittal craniectomy posterior to the coronal suture. A single stimulus of 325 mV for a duration of 0.1 to 0.5 ms was used to obtain a motor action potential from the contralateral lower extremity. Complete transsection of the spinal cord abolished the CEMAP. A progressive increase in pressure applied to the spinal cord with a progressive increase in duration produced loss of the CEMAP. The selective motor tract study made possible by cortical stimulation makes this a good technique for studying the motor tracts in experimental work.

Minimally Invasive Surgical Approach for Intractable Seizures

Minimally invasive procedures (multiple subpial transection, topectomy and amygdalahippocampotomy) were used to treat 24 patients with intractable seizures. The seizure foci were in both hemispheres i

Isolation of Dominant Seizure Foci by Multiple Subpial Transections

Dominant seizure foci (DSF) are seizure foci that do not respond to multiple subpial transections (MST). DSF were isolated in 15/31 patients who underwent MST in the past 6 years. These patients had MST over both hemispheres (6 patients) or over multiple lobes of one hemisphere (9 patients). DSF measured 0.5-1 cm in diameter and numbered 1-4 (in each patient). Their excision resulted in dramatic improvement in EEG over wide areas of the cortex. The longest postoperative follow-up is 67 months, with a median of 21 months. Nine of 15 patients are free of seizures, 3/15 have rare seizures, 2/15 have > 90% reduction in seizure frequency, and 1/15 has > 70% reduction in seizure frequency with improvement in motor and speech functions. In summary, DSF are resistant to MST and influence the electrical activity of the surrounding cortex. MST combined with excision of DSF resulted in good seizure control in this series, which included patients with multilobar and bihemispheric seizure foci.

The study of the effect of human chorionic gonadotrophic (HCG) hormone on the survival of adrenal medulla transplant in brain Preliminary study

SummaryAutologous adrenal cortex was completely dissected off the medula using microdissection. The adrenal medulla tissue was transplanted to the lateral ventricle in twenty-one adult rats. Group A consisting of ten animals received 200 units of HCG per 100 gram body weight daily for one week and then on every alternate day for seven weeks. The remaining rats (group B) served as control. After eight weeks the brains were removed and a volumetric study was done using histological sections. High pressure liquid chromatography (HPLC) with electrochemical detection for catecholamine assay of the graft was also undertaken. The graft survival in group A was significantly higher (p<0.005) than group B. The level of norepinephrine was significantly higher in group A while dopamine was higher in group B. The higher volume of graft tissue in group A suggests that HCG may help in increased survival and growth of the transplanted tissue. Higher levels of norepinephrine in group A would suggest a tendency for such grafts to be active to a greater extent with the treatment of HCG.