Faculty Bibliography

PURPOSE/OBJECTIVE:To describe the dynamic changes of the intraocular pressure (IOP) and intracranial pressure (ICP) with normal or pathological values (intracranial hypertension) in nonglaucomatous neurological patients during lumbar punction (LP). METHODS:Case-control study, prospective measurement of tonometry in both groups referred for LP. Intraocular pressure, ICP and translaminar pressure difference (TPD) were compared pre- and post-LP. RESULTS:were analysed. The initial mean ICP was 12.81 (± 6.6) mmHg. The mean TPD before and after the LP was 1.48 mmHg and 0.65 mmHg, respectively. The mean IOP of both eyes decreased to 0.8 mmHg post-LP in patients with pathological ICP (p = 0.0193) and normal ICP (p = 0.006). CONCLUSIONS:We found a statistically significant decrease of the IOP post-LP compared to the pre-LP in both groups, being higher in patients with pathological ICP. There were no significant differences of the IOP in patients with normal versus pathological ICP pre-LP/post-LP; neither was found a correlation between ICP and IOP.

BACKGROUND:Transcranial direct current stimulation (tDCS) has been evaluated in medication refractory epilepsy patients. The results have been inconclusive and protocols have varied between studies. OBJECTIVE:To evaluate the safety and efficacy of two protocols of tDCS in adult patients with mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS). METHODS:This is a randomized placebo-controlled, double-blinded clinical trial, with 3 arms, 3 sessions, 5 sessions and placebo stimulation. Frequency of seizures (SZs), interictal epileptiform discharges (IEDs) and adverse effects (AEs) were registered before and after treatment, and at 30 and 60 days follow-up. Descriptive statistics, k-related samples, Friedman's test, and relative risk (RR) estimation were used for analysis. RESULTS:We included twenty-eight subjects (3d n = 12, 5d n = 8, placebo n = 8), 16/28 (57%) men, age 37.8(±10.9) years old. There was a significant reduction of the frequency of SZs at one (p = 0.001) and two (p = 0.0001) months following cathodal tDCS compared to baseline in the 3 arms (p = 0.0001). The mean reduction of SZ frequency at two months in both active groups was significantly higher than placebo (-48% vs. -6.25%, p < 0.008). At 3 days (-43.4% vs. -6.25%, p < 0.007) and 5 days (-54.6% vs. -6.25%, p < 0.010) individual groups showed a greater reduction of SZs. A significant IED reduction effect was found between baseline and immediately after interventions (p = 0.041) in all groups. Side effects were minor. CONCLUSIONS:Cathodal tDCS technique of 3 and 5 sessions decreased the frequency of SZs and IEDs (between baseline and immediately post-tDCS) in adult patients with MTLE-HS compared to placebo tDCS.

BACKGROUND: Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation therapy in epilepsy with conflicting results in terms of efficacy and safety. OBJECTIVE: Review the literature about the efficacy and safety of tDCS in epilepsy in humans and animals. METHODS: We searched studies in PubMed, MedLine, Scopus, Web of Science and Google Scholar (January 1969 to October 2013) using the keywords 'transcranial direct current stimulation' or 'tDCS' or 'brain polarization' or 'galvanic stimulation' and 'epilepsy' in animals and humans. Original articles that reported tDCS safety and efficacy in epileptic animals or humans were included. Four review authors independently selected the studies, extracted data and assessed the methodological quality of the studies using the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, PRISMA guidelines and Jadad Scale. A meta-analysis was not possible due to methodological, clinical and statistical heterogeneity of included studies. RESULTS: We analyzed 9 articles with different methodologies (3 animals/6 humans) with a total of 174 stimulated individuals; 109 animals and 65 humans. In vivo and in vitro animal studies showed that direct current stimulation can successfully induce suppression of epileptiform activity without neurological injury and 4/6 (67%) clinical studies showed an effective decrease in epileptic seizures and 5/6 (83%) reduction of inter-ictal epileptiform activity. All patients tolerated tDCS well. CONCLUSIONS: tDCS trials have demonstrated preliminary safety and efficacy in animals and patients with epilepsy. Further larger studies are needed to define the best stimulation protocols and long-term follow-up.

OBJECTIVE: The study aimed to establish the prevalence of seizure history (SH) and epilepsy in a rural community in Hidalgo, Mexico and determine the patients' beliefs and attitudes towards the disease and its initial medical treatment. METHODOLOGY: A transverse, descriptive, door-to-door epidemiological study (April 2011-November 2012) was conducted with 863 inhabitants from Xocotitla, Huejutla, Hidalgo, Mexico (162 housing units). Patients with SH were identified with an adaptation of the WHO protocol for epidemiological studies of neurological diseases. Afterwards, the subjects identified with seizure history (SH) or epilepsy were interviewed with a 20-question Likert type questionnaire regarding the management and belief set of their SH. The interviews were conducted in Spanish and Nahuatl. RESULTS: The prevalence of epilepsy and isolated nonrecurring seizures was 38.2/1000 and 25.4/1000, respectively. Out of the total population of 863 inhabitants, 33/863 were identified with SH: only 39.3% were able to identify an epileptic seizure as such, 48.5% sought medical attention upon the first seizure, 33.3% used a traditional healer, 15.2% took no action, 3% sought a religious representative, 85% lacked any lab analysis, and 60% received no antiepileptic drugs. Only 39% received free local medical attention, 69.7% considered seizures and epilepsy to be a consequence of divine intervention, and 94% reported some type of discrimination. CONCLUSIONS: A high prevalence of epilepsy and SH was found in this rural community in Mexico. Divine/religious beliefs, discrimination, scarce access to basic health services and inadequate medical management of epilepsy and SH persist.

Aim. To describe the general aspects of cavernomas and epilepsy and review the available literature on the utility of electrocorticography (ECoG) in cerebral cavernoma surgery. Methods. We searched studies in PubMed, MedLine, Scopus, Web of Science, and Google Scholar (from January 1969 to December 2013) using the keywords "electrocorticography" or "ECoG" or "prognosis" or "outcome" and "cavernomas". Original articles that reported utility of ECoG in epilepsy surgery were included. Four review authors independently selected the studies, extracted data, and assessed the methodological quality of the studies using the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, PRISMA guidelines, and Jadad Scale. A meta-analysis was not possible due to methodological, clinical, and statistical heterogeneity of included studies. We analysed six articles with a total of 219 patients. Results. The most common surgical approach was lesionectomy using ECoG in the temporal lobe with Engel I outcome range from 72.7 to 100%. Conclusions. Small controlled studies suggest that ECoG-guided resection offers the best functional results in seizure control for subjects undergoing cavernoma surgery, especially in the temporal lobe.

BACKGROUND: To determine the reliability and usefulness of intraoperative monitoring of the abducens nerve during extended endonasal endoscopic skull base tumor resection. METHODS: We performed abducens nerve intraoperative monitoring in 8 patients with giant clival lesions recording with needle electrodes sutured directly into the lateral rectus muscles of the eye to evaluate spontaneous electromyographic activity and triggered responses following stimulation of the abducens nerves. RESULTS: A total of 16 abducens nerves were successfully recorded during endoscopic endonasal skull base surgeries. Neurotonic discharges were seen in two patients (12% [2/16] abducens nerves). Compound muscle action potentials of the abducens nerves were evoked with 0.1-4mA and maintained without changes during the neurosurgical procedures. No patient had new neurological deficits or ophthalmological complications post-surgery. CONCLUSIONS: Intraoperative monitoring of the abducens nerve during the extended endonasal endoscopic approach to skull base tumors appears to be a safe method with the potential to prevent neural injury through the evaluation of neurotonic discharges and triggered responses.

PURPOSE: Periodic epileptiform discharges (PEDs) are an uncommon, abnormal EEG pattern seen usually in patients with acute diseases and less frequently in chronic conditions, such as mesial temporal lobe epilepsy (mTLE). Evaluate the clinical histories, neuroimaging findings, and serial electrophysiological studies prior to the appearance of PEDs in patients with mTLE secondary to hippocampal sclerosis (HS). METHODS: We searched 19, 375 EEGs (2006-2012) for the presence of PEDs secondary to mTLE due to HS. RESULTS: 12 patients were included. The patients with PEDs had a high prevalence of psychiatric comorbilities, including major depression (50%), interictal psychosis (16%) and dementia (8%). All of the patients had intractable epilepsy with similar clinical findings. We observed a sequential neurophysiological worsening of the EEG patterns prior to the appearance of PEDs. Five patients with PEDs underwent epilepsy surgery and four were seizure free at follow-up 15 (+/-9) months. CONCLUSIONS: PEDs are rare in patients with mTLE and HS and their presence in these cases could reflect clinical severity and neurophysiologic worsening, clinically manifested by intractable epilepsy and severe psychiatric comorbidities. The presence of PEDs in EEGs of patients with mTLE, however, was not associated with poor postsurgical seizure-freedom.

Synchrotron-generated X-ray microplanar beams (microbeams) are characterized by the ability to deliver extremely high doses of radiation to spatially restricted volumes of tissue. Minimal dose spreading outside the beam path provides an exceptional degree of protection from radio-induced damage to the neurons and glia adjacent to the microscopic slices of tissue irradiated. The preservation of cortical architecture following high-dose microbeam irradiation and the ability to induce non-invasively the equivalent of a surgical cut over the cortex is of great interest for the development of novel experimental models in neurobiology and new treatment avenues for a variety of brain disorders. Microbeams (size 100 microm/600 microm, center-to-center distance of 400 microm/1200 microm, peak entrance doses of 360-240 Gy/150-100 Gy) delivered to the sensorimotor cortex of six 2-month-old naive rats generated histologically evident cortical transections, without modifying motor behavior and weight gain up to 7 months. Microbeam transections of the sensorimotor cortex dramatically reduced convulsive seizure duration in a further group of 12 rats receiving local infusion of kainic acid. No subsequent neurological deficit was associated with the treatment. These data provide a novel tool to study the functions of the cortex and pave the way for the development of new therapeutic strategies for epilepsy and other neurological diseases.

Callosotomy by radioneurosurgery induces slow and progressive axonal degeneration of white matter fibers, a key consequence of neuronal or axonal injury (radionecrosis). However, the acute effects are not apparent when using conventional MRI techniques. Diffusion tensor imaging (DTI) during the first week following radioneurosurgical callosotomy allowed evaluation of these microstructural changes. The present report details that the use of sequential DTI to evaluate axonal degeneration following radioneurosurgical callosotomy in a patient normalized with the data of six healthy subjects. We describe a 25-year old woman with symptomatic generalized epilepsy who underwent a radioneurosurgical callosotomy using LINAC (Novalis(R) BrainLAB). DTI was acquired at the baseline, 3 and 9 months and showed a progressive decrease of the fractional anisotropy values in the irradiated areas compared to the controls that could be interpreted as a progressive disconnection of callosal fibers related to the outcome.