Steven L. Lewis

Aetiology of transient global amnesia

The pathophysiology of transient global amnesia (TGA) has been obscure since the definition of this syndrome more than 30 years ago. Current hypotheses include migraine, seizure, or transient cerebral arterial ischaemia. However, none of these potential mechanisms explain both the absence of other neurological signs or symptoms during TGA, and its frequent precipitating activities: many of which would be expected to result in marked increases in venous return from the arms to the superior vena cava. Patients with TGA also commonly have a Valsalva manoeuvre at the onset of attacks. I suggest that a Valsalva manoeuvre, blocking venous return through the superior vena cava, may allow brief retrograde transmission of high venous pressure from the arms to the cerebral venous system, resulting in venous ischaemia to the diencephalon or mesial temporal lobes and to TGA.

Late appearance of dropped head syndrome after radiotherapy for Hodgkin's disease

We present three cases of dropped head syndrome that occurred as a complication of mantle field (i.e., lymph nodes of the neck, axillae, and mediastinum) or whole‐body radiation therapy for Hodgkins disease. These cases are characterized by a late onset (2–27 years after radiation treatment), fibrosis, and contraction of the anterior cervical muscles, and atrophy of the posterior neck and shoulder girdle. This report adds to the increasing literature about the late neurological complications of radiation therapy and describes a previously unrecognized cause of dropped head syndrome. Muscle Nerve, 2006

Severe topiramate-associated hyperthermia resulting in persistent neurological dysfunction

Topiramate has recently been reported to cause hyperthermia as a result of oligohydrosis, primarily in pediatric patients. All cases reported to date were clinically mild, without permanent systemic or neurologic dysfunction. We report a case of severe hyperthermia and subsequent ataxia and tremor in an adult treated with topiramate. To our knowledge, this is the first case of topiramate-associated hyperthermia to result in residual cerebellar and cognitive dysfunction.

Postoperative acute disseminated encephalomyelitis after exposure to microfibrillar collagen hemostat

Microfibrillar collagen hemostat, known by its trade name Avitene, has been used in neurosurgery for decades. Complications with this product have been documented in other surgical specialties and described as mostly immune-mediated foreign-body reactions that can lead to a granulomatous reaction. There has never been a case of disseminated encephalomyelitis associated with this topical hemostatic agent. In this report the authors present a case of postoperative acute disseminated encephalomyelitis after exposure to Avitene. Possible pathophysiological mechanisms are discussed and the pertinent literature is reviewed.

Development of a Reliable Multimedia, Computer-Based Measure of Clinical Skills in Bedside Neurology

Purpose. This study reports the development of reliable multimedia, computer-based measures of bedside neurology skills. Method. A consortium of neurologists and medical educators (1) identified bedside skills and (2) created a computer-based test. Test-item stems were multimedia clips of standardized patients. Options appeared as text. Sixty-one junior medical students responded to these items. Results. The 77-item test yielded a reliability coefficient of 0.85. Subgroup item analysis resulted in reliability coefficients of 0.73 for the 20-question “pretest” (Test A) and 0.75 for the 20-question “posttest” (Test B). Conclusion. Two sets of test items were developed that can be used as outcome measures in studies that assess the effectiveness of educational interventions in bedside neurology.

A multicenter study to provide evidence of construct validity in a computer-based outcome measure of neurology clinical skills.

Background Using computer-based simulation to assess clinical skill—a key competence for medical trainees—enables standardization and exposure to a broad sample of physical findings. The purpose of this study is to provide evidence of construct validity for a computer-based outcome measure of neurology clinical skills. Method A total of 128 medical students and neurology residents at four institutions volunteered to take a 34-question computer-based test designed to measure neurology clinical skills. Subjects were classified into three groups based on level of training: novice, intermediate, and experienced. Results Overall performance increased with level of training. Question difficulty discriminated between groups as predicted. Twenty-six of 34 individual items discriminated between novices and more advanced learners. This test separated learners at different levels of training with a consistency of .92. Conclusion This study provided evidence of construct validity for a computer-based outcome measure of neurology clinical skills.

Neurology Education: Current and Emerging Concepts in Residency and Fellowship Training

This article discusses the current and future state of neurology training. A priority is to attract sufficient numbers of qualified candidates for the existing residency programs. A majority of neurology residents elects additional training in a neurologic subspecialty, and programs will have to be accredited accordingly. Attempts are being made to standardize and strengthen the existing general residency and subspecialty programs through cooperative efforts. Ultimately, residency programs must comply with the increasing requirements and try to adapt these requirements to the unique demands and realities of neurology training. An effort is underway to establish consistent competency-testing methods.

Transient Global Amnesia and Migraine

CLINICAL HISTORY A 31-year-old woman presented with a history of transient memory problems. The day before, upon awakening at her normal time, she had trouble with her memory such as remembering events of the day before, the day of a dinner engagement the week before, and a movie she saw a week ago. The memory problem lasted all day and resolved by the next morning. Her father stated that her speech was normal but she just seemed confused. She had no associated headache or other neurologic or systemic symptoms or signs. There is a history of migraine without aura from childhood until 10 years ago and migraine aura without headache occurring once every couple of months for the past several years. Past medical history was otherwise negative. Neurological examination was normal. A MRI scan of the brain, complete blood count, chemistry profile, TSH, and vitamin B12 level were all normal. Question.—Is there a relationship between transient global amnesia and migraine?

Restricted Diffusion on Magnetic Resonance Imaging in Partial Status Epilepticus

A N 82-YEAR-OLD WOManwithhypertension and bipolar disorder was admitted with new-onset generalized tonic-clonic seizures. On admission, magnetic resonance imaging (MRI) results were normal and electroencephalography showed right posterior quadrant slowing. She was started on valproic acid. One week later, she was found to have a left hemiparesis and 20 hours of continuous rhythmic jerks of the left leg, arm, and abdomen with retained consciousness, consistent with partial status epilepticus. Magnetic resonance imaging (Figure 1) showed restricted diffusion in the right parietal, occipital, and medial frontal cortices, with corresponding low signal on apparent diffusion coefficient maps. Magnetic resonance angiography results were normal. Electroencephalography (Figure 2) showed right posterior quadrant epileptiform activity that correlated with the area of restricted diffusion. The seizures and hemiparesis resolved after treatment with phenytoin and lorazepam. Repeat MRI 4 weeks later showed resolution of the diffusion abnormality and nearcomplete resolution of the hyperintensities seen on fluid-attenuated inversion recovery images. Transient imaging abnormalities on computed tomography and MRI as well as nuclide studies have previously been described in partial status epilepticus. Reversible hypodensities have been reported on computed tomography, whereas hyperintensities on T2-weighted imaging and restricted diffusion on MRI have been reported with prolonged seizures. These findings may be mistaken for ischemia in the acute setting. A clue that the restricted diffusion is due to the ictal process rather than acute infarction is the finding that the diffusion-weighted imaging abnormalities do not conform to a specific vascular territory. The diffusion abnormalities in status epilepticus are thought to represent cytotoxic edema but not underlying ischemia. The etiology of the cytotoxic edema is unclear. Proposed mechanisms include failure of the sodium-potassium ion adenosine triphosphate pump leading to an influx of sodium ions and water and increased anaerobic glycolysis.

Reply from the Authors: Ginkgo biloba

Reply from the Authors: We appreciate the comments of Odawara et al. concerning our paper. We agree that our single case report does not prove that Ginkgo biloba contributed to the development of our patients subdural hematomas, and we have not provided unequivocal evidence that clinical platelet dysfunction or a hemorrhagic tendency occur with chronic Ginkgo ingestion. However, we disagree with some of …