Biomedical subjects

Nicholas D Lawn

Publications and source records attributed to Nicholas D Lawn.

5 recordsLinked to original sources

PubMed2006

First seizure presentation: do multiple seizures within 24 hours predict recurrence?

We compared clinical features and prognosis of 72 adults with a first-ever seizure presentation comprising multiple discrete seizures within 24 hours to 425 patients presenting with a single seizure. Those presenting with multiple seizures were no more likely to have seizure recurrence, irrespective of etiology or treatment. Hence, a presentation with multiple seizures within 24 hours should be regarded as a single event, in keeping with the International League Against Epilepsy recommendations.

Adolescent↗

PubMed2004

Ictal SPECT analysis in epilepsy: subtraction and statistical parametric mapping techniques.

Seizures are associated with an increase in regional cerebral blood flow (rCBF). In partial seizures the increased blood flow closely corresponds with the site of seizure origin. Using tracers that accumulate and remain "fixed" in different areas of the brain proportional to rCBF at the time of injection, ictal SPECT is now an important tool for localization of seizures in a presurgical evaluation. However, the best methods for interpretation of partial seizure-induced changes in rCBF remain unclear. Numerous computer-aided tools have been used to increase objectivity and accuracy of ictal SPECT analysis. This review examines the uses of ictal-interictal subtraction methods and statistical parametric mapping (SPM) to enhance interpretation and utility of ictal SPECT. The review covers the evolution of advanced ictal SPECT imaging analysis techniques and the authors' clinical experience with the use of subtraction and SPM methods. The authors discuss the impact of ictal SPECT subtraction or difference imaging methods and the initial evidence for proof-of-principle that SPM can be used to provide objective, accurate analysis of ictal SPECT scans in patients with temporal and extratemporal lobe epilepsy. The limitations of both methodologies are discussed, and suggestions for further study of validation, improvement, and routine clinical implementation of advanced analysis methods are provided.

Algorithms↗

PubMed2004

Ictal single-photon emission computed tomography imaging in extra temporal lobe epilepsy using statistical parametric mapping.

PURPOSE: To examine the application of statistical parametric mapping (SPM) to analyze ictal single-photon emission computed tomography (SPECT) scans in surgical candidates with extratemporal lobe epilepsy. METHODS: The authors selected patients who underwent successful ictal SPECT acquisition in the process of surgical treatment of intractable partial epilepsy. Thirteen patients were identified who met inclusion criteria for confident seizure localization from either intracranial electroencephalogram recordings or epilepsy surgery outcome. In these cases, ictal scans were registered to an in-house-developed normal SPECT atlas composed of 14 spatially normalized brains of normal subjects. SPM96 was used to test on a voxel-by-voxel basis for statistically significant increases in blood flow associated with each patient's ictal scan. The results were then mapped back onto the patient's magnetic resonance image (MRI) for final interpretation. Statistical parametric mapping (SPM) analysis of ictal SPECT scans was compared to both conventional visual interpretation and the analysis of subtraction ictal SPECT co-registered to MRI (SISCOM). RESULTS: Ten of 13 patient scans showed localizing focal ictal increases in regional cerebral blood flow, all of which were concordant with ultimate epilepsy localization. Of the 3 cases not localized with SPM, 1 was localized by conventional visual interpretation and another, not localized by visual interpretation, was correctly localized with SISCOM. Two cases not localized by SISCOM were localized by both visual and SPM analysis. CONCLUSIONS: This work provides supportive evidence for proof of principle that SPM can be used to provide objective, accurate analysis of ictal SPECT scans in patients with extratemporal lobe epilepsy.

Adolescent↗

PubMed2003

Clinical, magnetic resonance imaging, and electroencephalographic findings in paraneoplastic limbic encephalitis.

OBJECTIVE: To analyze clinical presentation of and paraclinical test abnormalities in patients with paraneoplastic limbic encephalitis (PLE). PATIENTS AND METHODS: We retrospectively reviewed 24 patients seen at the Mayo Clinic in Rochester, Minn, between 1985 and 2002 in whom PLE was suspected. Patients were identified on the basis of clinical history and presence of cancer. Data were reviewed from magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, electroencephalography (EEG), and paraneoplastic serologic studies. RESULTS: Common manifestations were cognitive dysfunction (92%), seizures (58%), and psychiatric symptoms (50%); 13 patients had small cell lung carcinoma; 11 had other malignancies. Paraneoplastic neuronal autoantibodies were found in 14 (64%) of 22 patients tested. Electroencephalography showed focal or generalized slowing and/or epileptiform activity, maximal in the temporal regions, in all 22 patients tested. Magnetic resonance imaging revealed increased T2 signal involving one or both temporal lobes in 15 (83%) of 18 patients. Cerebrospinal fluid test results were abnormal in 18 (78%) of 23 patients tested. Clinical or radiographic evidence of extralimbic involvement was documented in 12 (55%) of 22 patients. No abnormality on EEG, MRI, or CSF analysis correlated with a specific cancer type or with a specific paraneoplastic autoantibody. CONCLUSIONS: In patients with suspected PLE, EEG is invaluable for confirming cerebral dysfunction. Magnetic resonance imaging can show unequivocal involvement of temporolimbic structures and helps exclude other diagnoses. When EEG and cranial MRI are both normal, PLE is unlikely. Comprehensive testing for paraneoplastic neuronal nuclear, cytoplasmic, and ion channel autoantibodies is an important part of the evaluation, but negative results do not rule out PLE.

Adult↗

PubMed2002

Progress in clinical neurosciences: Status epilepticus: a critical review of management options.

Although generalized tonic-clonic status epilepticus (SE) is frequently seen, an evidence-based approach to management is limited by a lack of randomized clinical studies. Clinical practice, therefore, relies on a combination of expert recommendations, local hospital guidelines and dogma based on individual preference and past successes. This review explores selected and controversial aspects of SE in adults and provides a critical appraisal of currently recommended management strategies.

Decision Trees↗