Tak Lap Poon

By Tak Lap Poon

Drug-resistant epilepsy (DRE) is defined as failure of two adequate trials of appropriately chosen and administered antiepileptic drugs. Approximately about 30% of epilepsy patients are drug resistant. Accountable reasons to treatment failure including failure to recognize epilepsy syndrome, poor drug compliance, lifestyle factors, etc. In modern era of medicine, DRE patient should be encouraged to have early referral to tertiary epilepsy centre for presurgical evaluation. Comprehensive neurophysiology, structural neuroimaging, and neuropsychological and psychiatric assessment are regarded as essential elements. Invasive electroencephalography (EEG) monitoring in terms of subdural electrodes, depth electrodes, foramen ovale electrodes, and more advanced technique using stereoelectroencephalography (SEEG) are strong armamentarium for epilepsy surgeon. Epilepsy surgery in terms of resection, disconnection, or neuro-modulation should be recommended after a multi-disciplinary agreement.

Part of the book: Epilepsy

By Tak Lap Poon and Ka Wing See

Meningiomas are the second common Central Nervous System (CNS) neoplasm, and are the most common benign intracranial tumor. They approximately constitute up to 30% of all intracranial tumors. They arise from the arachnoidal coverings of brain. Presentation varies and depends on size, number and location of tumors. Symptoms include those related to increased in intracranial pressure, local irritative features including seizure and local pressure effect to eloquent areas, white matter tracts and cranial nerves. Management of meningiomsa is always challenging and multi-disciplinary approaches includes surgery, radiotherapy and possible chemotherapy and immunotherapy. Among radiation therapy treatment, stereotactic radiosurgery (SRS) or stereotactic radiosurgery (SRT) is getting the popularity compared to traditional conformal radiotherapy with comparable tumor control rate.

Part of the book: Brain Tumors

By Joyce Shuk Wan Chow and Tak Lap Poon

Cryptogenic epilepsy, accounting for ~40% of adult-onset epilepsies and a lesser proportion in paediatrics, is defined as epilepsy of presumed symptomatic nature in which the cause has not been identified. It has a higher prevalence of refractory seizures when compared to those with idiopathic epilepsy (40 vs. 26%). These patients are usually treated with multiple anti-epileptic drugs, yet the total number of which used is inversely proportional to their efficacy. Moreover, these children may have significantly worse behavioural problems and can result in substantial cognitive impairments when older. Luckily, the number of cryptogenic epilepsy cases is diminishing due to better diagnostic abilities in recent years. We aim to divide this chapter into three parts. First, we hope to discuss our working algorithm and explain the use and advantages of different imaging modalities including high-field 3-Tesla MRI with morphological analysis for accurate localisation of the epileptogenic foci. We shall then elaborate the concept of the epileptogenic circuit and explore the selection criteria for more invasive approaches, such as depth electrodes and SEEG. Last but not the least, we aim to discuss the surgical treatments, including VNS and DBS, and their outcomes in these patients.

Part of the book: Epilepsy