Education Research: The challenge of incorporating formal research methodology training in a neurology residency.

BACKGROUND: Physicians often do not have good understanding of research methodology. Unfortunately, the mechanism to achieve this important competency in a busy neurology residency program remains unclear. We tested the value and degree of acceptance by neurology residents of a multimodal educational intervention that consisted of biweekly teaching sessions in place of an existing journal club, as a way to provide formal training in research and statistical techniques. METHODS: We used a pre- and post-test design with an educational intervention in between using neurology residents at the University of Iowa as subjects. Each test had 40 questions of research methodology. The educational intervention consisted of a biweekly, structured, topic-centered, research methodology-oriented elective seminar following a year-long predefined curriculum. An exit survey was offered to gather resident's perceptions about the course. RESULTS: While a majority of residents agreed that the intervention enhanced their knowledge of research methodology, only 23% attended more than 40% of the sessions. There was no difference between pretest and post-test scores (p = 0.40). CONCLUSIONS: Our experience suggests that, in order to accomplish the Accreditation Council for Graduate Medical Education goals regarding increasing competency of residents in knowledge about research methodology, a major restructuring in the neurology residency curriculum with more intense formal training would be necessary.

The differences in electroencephalographic changes in patients undergoing carotid endarterectomies while under local versus general anesthesia.

OBJECTIVE: This study compared the electroencephalographic (EEG) changes occurring during carotid occlusion in 225 consecutive patients undergoing carotid endarterectomies performed by two surgeons, one using local and the other using general anesthesia. METHODS: A retrospective review of patients undergoing carotid endarterectomies for carotid occlusive disease was conducted. EEG changes associated with intraoperative ischemia (decreased amplitude, generalized slowing, and loss of fast activity) resulting in the need for an indwelling arterial shunt were recorded for the two anesthesia groups. To determine the similarities or differences between the two groups, the groups were compared regarding age, risk factors, and indications for surgery. RESULTS: Significant EEG changes were noted in 6 of 96 patients (6.3%) in the local anesthesia group versus 19 of 121 patients (15.7%) in the general anesthesia group. EEG changes consisted solely of generalized slowing in the local anesthesia group, whereas a more varied spectrum was observed in the general anesthesia group. The two groups were similar regarding age and risk factors. Although the local anesthesia group had more asymptomatic patients, symptomatic patients did not have a greater incidence of EEG changes. CONCLUSION: There is a large difference in EEG changes potentially requiring shunt placement in patients undergoing surgery while under local (6.3%) versus general (15.7%) anesthesia. This could not be explained based on age, risk factors, interpretation of EEG findings, or indications between the two groups. We conclude that EEG monitoring may be insensitive and may fail to detect ischemia in patients who are under regional anesthesia. Alternately, the presence of general anesthetics may alter the character of the EEG findings and increase the sensitivity of EEG monitoring to ischemic events.

Chronic microelectrode investigations of normal human brain physiology using a hybrid depth electrode.

Neurosurgeons have unique access to in vivo human brain tissue, and in the course of clinical treatment important scientific advances have been made that further our understanding of normal brain physiology. In the modern era, microelectrode recordings have been used to systematically investigate the cellular properties of lateral temporal cerebral cortex. The current report describes a hybrid depth electrode (HDE) recording technique that was developed to enable neurosurgeons to simultaneously investigate normal cellular physiology during chronic intracranial EEG recordings. The HDE combines microelectrode and EEG recordings sites on a single shaft. Multiple microelectrode recordings are obtained from MRI defined brain sites and single-unit activity is discriminated from these data. To date, over 60 HDEs have been placed in 20 epilepsy surgery patients. Unique physiologic data have been gathered from neurons in numerous brain regions, including amygdala, hippocampus, frontal lobe, insula and Heschl's gyrus. Functional activation studies were carried out without risking patient safety or comfort.

A chronic microelectrode investigation of the tonotopic organization of human auditory cortex.

We investigated the functional organization of human auditory cortex using a new chronic microelectrode technique. Tonotopic mapping data was obtained at the single unit level for the first time in humans. All sound-driven units were noted to have frequency-dependent response patterns. The majority of units (73%) demonstrated sharply tuned excitatory best-frequency responses. Twenty seven percent of units showed wide receptive fields, representing excitatory responses to almost the entire range of frequencies presented. A tonotopic pattern was observed with best frequencies systematically increasing as more medial-caudal recording sites were sampled.

A hybrid clinical-research depth electrode for acute and chronic in vivo microelectrode recording of human brain neurons. Technical note.

For several decades, important scientific information has been gained from in vivo microelectrode recordings of individual human cerebral cortical neurons in patients with epilepsy. The experimental methods used, however, are technically complex and require a highly skilled intraoperative team. There are also significant experimental time limitations, as well as constraints on the type of behavioral tests conducted, and the brain regions that may be safely studied. In this report, a new method is described for obtaining in vivo microelectrode recordings using a hybrid depth electrode (HDE). High-impedance research recording contacts are interspersed between low-impedance clinical electroencephalographic (EEG) contacts along the HDE shaft. The HDE has the same external physical properties as a standard clinical depth electrode (DE). Following preclinical laboratory testing, 15 HDEs were used in the evaluation of six patients with medically refractory epilepsy. High-quality EEG recordings were obtained in all cases (two acute intraoperative, four from the chronic epilepsy monitoring unit). Action potentials from individual neurons were successfully recorded during all experimental sessions; however, the chronic preparations were clearly superior. Chronic HDEs are placed using a standard stereotactic system, and the locations of recording contacts are documented on a postimplantation imaging study. The quality of the chronic research recordings was excellent over study periods ranging from 5 to 14 days. The patients rested comfortably on the ward and were able to cooperate with complex experimental instructions. Basic neuroscientists participated fully in all aspects of the chronic investigations. The use of an HDE in place of a standard clinical DE may now allow detailed physiological investigations of any brain region targeted for clinical DE implantation.

A noninvasive, reattachable skull fiducial marker system. Technical note.

As computer-interactive technologies become more widely used in neurosurgery, radiology, and radiation therapy, the need for an optimum skull fiducial marker system increases. In the past, intracranial localization methods required precisely machined metal frames and rigid pin fixation to the skull. Recently, this function has been performed using "frameless" computer-based systems that calculate brain position relative to a series of external reference points, the most accurate of which are screwed directly into the skull. A penetrating fiducial marker system, however, is not well suited for applications requiring multiple volume registrations over an extended time period. We describe a new skull fiducial marker system that attaches to the maxillary teeth and can be used repeatedly on different occasions. A curved bar, known as a Banana Bar (BB) extends backward from a custom mouthpiece around the side of the patient's head; the bar contains sites of attachment for screw-in radiographic fiducial markers. Repositioning accuracy was quantitated using a photographic technique. A BB prototype was constructed and tested in three subjects. The BB weighs less than 100 g and can be comfortably held in position for up to 30 minutes. It takes less than 1 minute to screw in the mouthpiece and only seconds to secure the BB to the teeth. One hundred twenty photographic measurements were analyzed from 60 repositionings over a minimum 3-week period. Standard deviations for the measurement series ranged from 0.29 to 0.86 mm. Results suggest that the BB may be an inexpensive, efficient, and accurate method for providing the external reference points needed for a wide range of emerging computer-interactive applications.

Ranitidine-induced cranial dystonia.

We report a case of cranial dystonia related to the administration of ranitidine. The symptoms started shortly after institution of treatment, resolved after discontinuation, and recurred upon repeat administration of the drug. Although there have been a few reports of abnormal involuntary movements related to other histamine2 antagonists, this is only the second reported instance due to ranitidine and the first reported instance of dystonia related to the drug. The pathophysiology of this effect is unclear, but a central cholinergic effect of this agent may be a contributing factor.

Nonconvulsive status epilepticus: EEG analysis in a large series.

We analyzed EEG characteristics comprehensively in a large series of nonconvulsive status epilepticus (NCSE) cases. Eighty-five ictal episodes in 78 patients were analyzed. The ictal discharges were generalized (group G) in 59 episodes (69%), diffuse with focal predominance (group GF) in 15 (18%), and focal (group F) in 11 (13%). The morphologies and patterns of persistence varied greatly. Frequency of ictal discharge was also variable and was almost always < 3 Hz. Demonstration of focal epileptic features in response to intravenous (i.v.) diazepam (DZP) and the presence of interictal focal epileptiform discharges in some cases in groups G and GF suggested possible focal onset secondarily generalized in these cases. This study suggests that electrographically NCSE is a highly heterogeneous epileptic state, and i.v. DZP may serve as a valuable diagnostic tool in differentiating generalized from focal onset NCSE.

Neuroleptic malignant syndrome or parkinsonism hyperpyrexia syndrome.

NMS is a rare and idiosyncratic reaction that occurs with the use of dopamine antagonists or the withdrawal of dopamine agonists from patients with IP. It is a clinical diagnosis based on the presence of parkinsonism and hyperpyrexia in the appropriate pharmacologic setting. If any of these factors is absent, the diagnosis cannot be made. NMS is probably caused by the reduction of dopaminergic activity in the CNS, mainly in the hypothalamus and striatum. Prompt recognition and initiation of supportive and specific therapies optimize survival. Reexposure to neuroleptic drugs, if necessary, is usually possible if done cautiously. Considering that NMS is not solely related to neuroleptics and is less often malignant than not, perhaps the name should be changed to reflect its principal clinical features and underlying pathogenesis. We suggest parkinsonism hyperpyrexia syndrome.