PREPARED BY: DR.MOHAMMED H. ALKHAISHANI OTHER MODALITIES IN THE TREATMENT OF EPILEPSY

ELECTRICAL NEUROMODULATIONS These approaches for extratemporal lobe epilepsy,if despite resection of epileptogenic foci,epilepsy persists or in the palliative circumstance where no seizure focus is demonsrated using scalp recording.

Trigeminal nerve stimulation -Has recently been reported. -In one study on 12 patients,they have 66% seizure frequency reduction at 3 months follow up -Side effects include;orbicularis occuli twitching and dental discomfort and paresthesia. -Still under big trials for it’s superiority over vagus nerve stimulation

Vagus Nerve Stimulation (VNS) -Has been approaved in many countries for; 1- Partial seizures with or without secondary generalization in children older than 12 year 2-Generlaized epilepsy as an adjunct therapy to resective surgical procedures (when they are insufficient ) in children younger than 12 years 3-Patients who is not candidate for surgical resection as tuberous sclerosis complex 4-Patients who refused surgical resection surgical resection when typically indicated achieves higher rates of seizure control.

VNS Trials show differences in seizure frequency reduction between % with high frequency, and 6-15 % with high frequency stimulation. -In one study on 454 patients,median seizure reductions were 44% from base line after 3 years. With 43% of patients having at least 50% seizure frequency reduction, and 20% have persisting hoarseness of voice at 2 years of follow up.

HISTORICAL BACK GROUND -Experiments first shows that intermittent VNS reduced or eliminated interictal epileptic events that were chemically induced in the frontal cortex of cats. In 1987,a company cyberonics was founded to develop VNS therapy in humans. In 1988 the first pt. to undergo implantation of a VNS device became seizure free. Since that time,more than 46,000 neurocybernetic prosthesis(NCP)has been implanted to treat epilepsy worldwide.-

Mechanism -The NCP delivers intermittent afferent electrical stimulation to the left cervical vagus nerve trunk, wich secondarily transmits impulses that exert widespread effects on neuronal excitability throughout the CNC.

COMPLICATIONS -Infection. -Vocal cord paralysis. -Brady cardia\asystol -Malfunctioning -Sleep-related breathing disorders ****Future is promising

DEEP BRAIN STIMULATION FOR EPILEPSY(DPS) -Although palliative,DBS has the advantage of tissue preservation and also the potential ability to influence multifocal epilepsy. -Generlaized tonic-clonic seizures appeared to show the best response.

Indications a-In temporal lobe epilepsy ; for bilateral mesial temporal sclerosis,if one is dominent in epilepsy firing(for the non-dominant one after surgical resection of the dominant side) b-For extratemporal epilepsy ; 1-if epilepsy persists despite resection of the epileptogenic foci. 2-if no epilepsy focus is demonstrated using scalp recording.

Surgical Approaches for Epilepsy 1-Resective surgery -Temporal lobe resections: “standard,” - amygd.hiamygdalohippocampectomy (SAH) -Extratemporal resections -Lesional resections -Anatomic hemispherectomy 2-Disconnection surgery -Corpus callosotomy -Keyhole hemispherotomies -Multiple subpial transection (MST) 4-Neuroaugmentive surgery -Vagal nerve stimulation (VNS) -Deep brain stimulation (DBS) 5-Radiosurgery

Radiation Therapy of Epilepsy -Stereotactic radiosurgery(SRS) developed to treat functional disorders such as pain and movement disorders. -The earliest widespread uses of SRS focused on deep-seated tumors or AVM located in eloquent regions of the brain, using it as a means of treating these lesions while avoiding the risks associated with surgical resection. - -With in these contexts, seizures were treated as secondary manifestations of the primary disorder, rather than as specific conditions. -Subsequent to radiosurgical treatment, significant reduction, or even resolution, of the associated seizures has been documented.

MODERN INDICATIONS 1-Hypothalamic hamartomas 2-Mesial temporal lobe epilepsy : that associated With mesial temporal sclerosis 3-Secondary epilepsies: to tumors and AVM 4-Non-lesional epilepsies: especially SRS or corp. callosotomy

GAMMA SURGERY FOR EPILEPSY -The interest in using gamma surgery for epilepsy was triggered by an early report that seizures were alleviated in aseries of (AVM)case. -In 59 of the 247 patients with seizure as the presenting symptom,treated using gamma knife surgery between 1970 and 1984,the treatment resulted in ;relief of some or all seizures in 52 of these patients,11 were successfully taken off anticonvulsant medication, and in 3 patients seizure disorder symptoms were eleminated,although the AVM itself was un affected by the radiation.

LOCAL EFFECT -Biochemical analysis of changes after gamma surgery (in non human models),showed changes in the concentrations of excitatory and inhibitory aminoacids, particularly GABA. -One study shows that,patients with low grade astro- cytomas and assosiated epilepsy had significant relief from seizures following interstitial radiosurgery. SPECT scanning showed a reduced number of GABA receptors prior to treatment in both the tumors and sorrounding brain. Levels of these receptors increased following therapy. -These studies show that functional changes may occur at the cellular level without gross structural damage.

LONG TERM OUTCOME -Not promising because non of those patients is seizure-free after 138 months of follow up(unknown mechanisim). -The safety and short- term efficacy of gamma surgery for the treatment of epilepsies arising from space occupying lesions (e.g. low grade gliomas, hypothalamic hamartomas, cavernous malformations,and arteriovenous malformations) Make it an attractive option. -The gamma knife’s long-term feasibility and effectiveness for MTLE need to be proved.

Why there is amelioration of seizures following radio-surgery -The mechanism is exactly unknown -Some have suggested a “neuromodulation” phenomenon following gamma surgery With accompanying glial cell reduction,stem cell migration,neuronal plasticity and sprouting, and biochemical changes(rigorous scientific studies are far lacking)T

CONCLUSION -The indications and usefulness of gamma surgery for functional disorders are being defined more carefully with the passage of time -The advances of neuroimaging in the last several decades have offered the identification of discrete thalamic, subthalamic, and basal ganglia nuclei with acceptable confidence. -The ongoing developments of non-invasive physiologic monitoring will influence the development of gamma surgery for epilepsy. -When every thing is considerd,one may contend that while gamma surgery may be used for functional diseases of the brain,the current efficacy of alternative methods significantly limits the role of gamma surgery in the management of these diseases.

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