Optimizing and simplifying post-traumatic amnesia testing after moderate-severe traumatic brain injury despite common confounders in routine practice.

The duration of post-traumatic amnesia (PTA) following traumatic brain injury (TBI) is a key diagnostic and outcome indicator. However, concerningly, different PTA paradigms record different PTA durations: some over-estimate, others under-estimate, PTA. Thus, a compromise is implied. The potential effect of in-hospital confounders including opioids is unknown. Three clinical groups were prospectively recruited. Group-1: in-patients with moderate-severe-TBI (MS-TBI), considered likely 'in-PTA'. Group-2: patients rehabilitating after recent MS-TBI, considered 'out-of-PTA'. Group-3: orthopaedic in-patients without TBI undergoing elective surgery. Only Groups 1&3 were taking opioids. All were administered the Westmead Post-traumatic Amnesia Scale (WPTAS) and the Galveston Orientation and Amnesia Test (GOAT). Results were obtained in n = 56 (Group-1:n = 18, Group-2:n = 13 and Group-3:n = 25). On WPTAS, Groups 1&3 scored similarly, but significantly lower than, Group-2 (χ2 = 8.2, P = 0.017). Contrariwise, on GOAT, Group-1 scored significantly lower than Groups 2&3 (χ2 = 23.99, P < 0.001): however, no patient scored GOAT <75. WPTAS showed moderate sensitivity (72%) but poor specificity (40%) in distinguishing Group-1 from Groups 2&3. Contrariwise, GOAT showed 100% specificity but 0% sensitivity. WPTAS 'day of week' and 'pictures' combined with GOAT 'transport medium to hospital', 'anterograde amnesia' and 'retrograde amnesia' maximized sensitivity (100%), specificity (85-88%), PPV (77-83%) and NPV (100%) in distinguishing Group-1 from Groups 2&3. CONCLUSIONS: Confounders including opioids likely affected WPTAS overall, but not GOAT specificity. A merger, whereby WPTAS sensitivity augmented GOAT specificity, was therefore sought. Favourable items from WPTAS (4/12) and GOAT (3/10) together optimized, and yet simplified, PTA testing; despite prevalent clinical confounders. Less, not more, 'PTA' items would benefit both patients and staff alike.

Expanding the clinical spectrum of central pontine myelinolysis.

Central Pontine Myelinolysis (CPM) is a clinical entity first described by Adams et all in 1958 in the context of malnourishment and alcoholism. Classically, this demyelinating disease arises from the rapid correction of hyponatraemia, resulting in profound neurological deficits such as spastic quadraplegia and pseudobulbar palsy. Diagnosis is usually made on the presence of a symmetrical, centralized and well-circumscribed lesion in the pens, seen on MRI. Extrapontine lesions have also been described, frequently affecting the midbrain, thalamus, cerebellum and rarely extends to the medulla. We present a case of a 41 year old lady who presented with acute neurological deterioration, with physical signs to suggest a disease process involving the whole brainstem. However, MRI brain showed a lesion similar to that found in CPM, at the junction of the pons and medulla.

VNS in patients with previous unsuccessful resective epilepsy surgery: antiepileptic and psychotropic effects.

OBJECTIVES: To assess the efficacy of vagus nerve stimulation (VNS) in patients with medically and surgically intractable complex partial seizures (CPS). PATIENTS AND METHODS: Sixteen patients with previous temporal [15] and frontal [one] resections were treated with VNS between 1994 and 1999 at King's College Hospital, London, UK. Post-operative video-electroencephalogram telemetry had shown that CPS started from the operated side in 12 patients, contralaterally in three and bilaterally independently in one. RESULTS: Three patients (18.75%) had 50% or more reduction in seizure frequency, but one showed severe worsening of epilepsy, which remitted upon VNS discontinuation. The antiepileptic effect of VNS was not different with respect to the type of operation (anterior temporal lobectomy vs amygdalohippocampectomy), the side of operation, or the side of seizure onset. We observed psychotropic effects in two patients with post-ictal psychosis, in two others with depression, and in a child with severe behavioral disorder. CONCLUSIONS: VNS may have a rather limited antiepileptic role to play in patients with persistent seizures following epilepsy surgery, but may independently possess useful antipsychotic and mood-stabilizing properties.

Postictal psychosis after temporal lobectomy.

Three of 282 consecutive patients who had temporal resections for intractable epilepsy developed postoperative postictal psychosis. These three patients had seizure recurrence contralateral to the resection, whereas none of the patients with ipsilateral seizure recurrence developed any psychiatric symptoms after surgery. Two had left amygdalo-hippocampectomy and one right temporal lobectomy. The de novo occurrence of postoperative postictal psychosis is a well-defined complication of surgery for temporal lobe epilepsy, and may relate to contralateral epileptogenesis.

Effect of high-altitude exposure on myopic laser in situ keratomileusis.

PURPOSE: To study the effect of high-altitude exposure on visual acuity after myopic laser in situ keratomileusis (LASIK). SETTING: Aconcagua, Mendoza, Argentina. METHODS: In the early postoperative period after uneventful myopic LASIK, 2 physicians prospectively assessed their visual acuity during an ascent of Aconcagua (22841 feet). The distance uncorrected visual acuity (UCVA) and peripheral oxygenation were measured at approximately every 2000 feet of altitude. RESULTS: Both climbers developed a moderate loss of distance UCVA but described normal near and pinhole acuity consistent with a myopic shift. The distance UCVA diminished to 20/100 in the right eye and 20/125 in the left eye of Climber A and to 20/160 and 20/30, respectively, of Climber B. The vision loss worsened with increased altitude, duration of exposure, and decreased peripheral oxygenation. One week after the climb, the manifest refraction demonstrated a small myopic shift in both eyes of Climber A; these subsequently resolved. CONCLUSIONS: Two climbers, 8 and 14 weeks after myopic LASIK, experienced vision loss consistent with a temporary myopic shift in the refractive error with ascent to high altitude. Climbers who have LASIK, particularly those in the early postoperative period, should be prepared for visual acuity fluctuations with high-altitude exposure.

Sudden withdrawal of carbamazepine increases cardiac sympathetic activity in sleep.

OBJECTIVE: To evaluate the cardiac autonomic effects of abrupt withdrawal of carbamazepine (CBZ) during sleep in patients with epilepsy. BACKGROUND: The pathophysiology of sudden unexpected death in epilepsy (SUDEP) is uncertain, with ictal or peri-ictal cardiorespiratory compromise appearing probable. Risk factors for SUDEP include multiple antiepileptic drugs (AED), poor compliance, and abrupt AED withdrawal. The spectral analysis of the beat-to-beat heart rate variability (HRV) displays two main components: low frequency (LF), representing sympathetic and parasympathetic influence and high frequency (HF), representing parasympathetic influence. The LF/HF ratio is commonly regarded as an indicator of sympathovagal balance. METHOD: Twelve patients with medically intractable seizures underwent abrupt withdrawal of CBZ to facilitate seizure recording during controlled circuit TV-EEG monitoring. Continuous EKG recording was begun 24 hours before CBZ reduction. Spectral analysis of the HRV was performed during selected samples of non-REM sleep before and after CBZ reduction. Analyses were made at least 6 hours after from (complex) partial and 12 hours from generalized seizures. RESULTS: The mean LF/HF ratio before withdrawal of CBZ was 2.15 compared with a ratio of 2.65 on day 4 after withdrawal, an increase of 19% (geometric mean; 95% CI, 2% to 34%; Wilcoxon test, z = 2.36; p = 0.018). The ratio increased in 10 patients compared with a decrease in only one patient. CONCLUSION: Abrupt withdrawal of CBZ leads to enhanced sympathetic activity in sleep as evidenced by increased LF/HF ratios. Increased sympathetic activity in the setting of seizure-induced hypoxia could predispose to SUDEP.

Prognostic factors in the surgical treatment of medically intractable epilepsy associated with mesial temporal sclerosis.

OBJECTIVES: To assess the prognostic factors determining seizure remission after temporal lobectomy for intractable epilepsy associated with mesial temporal sclerosis (MTS) at pathology. METHODS: The clinical and investigative features of 116 consecutive patients who had temporal lobe surgery for drug-resistant epilepsy and MTS at pathology were assessed using actuarial statistics and logistic regression analysis. RESULTS: At a median follow-up of 63 months the probability of achieving at least a 1-year period of continuous seizure freedom was 67%. Factors contributing to a favourable outcome were interictal EEG localization to the operated lobe and the absence of secondarily generalized seizures. These were also selected in the multivariate analysis, although at lower statistical significance (P=0.08 and 0.09, respectively). Perinatal complications were associated with a significantly worse outcome but overall, complicated febrile convulsions and congruent neuropsychological deficits were not significantly predictive variables. CONCLUSIONS: The present findings may aid in the non-invasive presurgical assessment of patients with intractable TLE and clinical and neuroimaging evidence of MTS.

Postoperative myoclonus simulating seizure recurrence: a rare complication of anterior temporal lobectomy.

The unusual case of newly-emerged bilateral myoclonus in a 39-year-old man following anterior temporal lobectomy, which cured his temporal lobe epilepsy, is reported. The possible causes and differential diagnosis between epileptic and non-epileptic myoclonus following epilepsy surgery are presented and a brief review of the available literature on the subject is reported.

Predictors of outcome and pathological considerations in the surgical treatment of intractable epilepsy associated with temporal lobe lesions.

OBJECTIVES: To evaluate the influence of clinical, investigative, and pathological factors on seizure remission after temporal lobectomy for medically intractable epilepsy associated with focal lesions other than hippocampal sclerosis. METHODS: From a series of 234 consecutive "en bloc" temporal resections for medically intractable epilepsy performed between 1976 and 1995, neuropathological examination disclosed a focal lesion in 80. The preoperative clinical, neuropsychological, interictal EEG, and neuroimaging characteristics of these patients were assembled in a computerised database. The original neuropathological material was re-examined for lesion classification and completeness of removal. The presence of additional cortical dysplasia and mesial temporal sclerosis was also noted. Survival analysis was performed using Kaplan-Meier curves and actuarial statistics. Logistic regression analysis was used to establish the independent significance of the clinical variables. RESULTS: The probability of achieving a 1 year seizure remission was 71% by 5 years of follow up. Factors predicting a poor outcome on multivariate analysis included the need for special schooling and a long duration of epilepsy. Generalised tonic-clonic seizures, interictal EEG discharges confined to the resected lobe, demonstration of the lesion preoperatively on CT, and complete histological resection of the lesion were not predictive of outcome. Neuropsychological tests correctly predicted outcome in left sided cases but apparently congruent findings in right sided resections were associated with a poor outcome. Pathological reclassification established the dysembryoplastic neuroepithelial tumour as the commonest neoplasm (87%) in this series, with a significantly better seizure outcome than for developmental lesions, such as focal cortical dysplasia. CONCLUSIONS: The findings highlight the importance of dysembryoplastic neuroepithelial tumour in the pathogenesis of medically refractory lesional temporal lobe epilepsy and the prognostic significance of preoperative duration of epilepsy emphasises the need for early recognition and surgical treatment. Cognitive and behavioural dysfunction, however, is associated with a lower seizure remission rate, independent of duration of epilepsy.

Psychomotor EEG variant of Gibbs: an association with underlying structural pathology.

OBJECTIVE: To describe the association between a unilateral mid-temporal rhythmic theta discharge ("psychomotor variant of Gibbs") with neuroimaging-demonstrated underlying mass lesion. METHODS: Standard routine awake and scalp electroencephalography, continuous video-EEG monitoring and magnetic resonance brain imaging were employed in the diagnostic work-up of a 9-year-old boy with a severe behavioural disturbance and episodic outbursts of aggression. RESULTS: EEG showed a unilateral mid-temporal rhythmic discharge which was continuous in drowsiness and which remained confined to the right hemisphere. MRI showed a lesion in the temporal horn of the right lateral ventricle displacing superiorly the white matter stem of the right temporal lobe. CONCLUSION: A rhythmic mid-temporal theta discharge, commonly regarded as a benign EEG variant, may, in some patients, reflect underlying structural pathology. Neuroimaging should be considered particularly when this EEG pattern remains confined to one hemisphere.

Chronic encephalitis and temporal lobe epilepsy: a variant of Rasmussen's syndrome?

The authors report two adult patients with chronic temporal lobe epilepsy and pathologic features consistent with Rasmussen's encephalitis. Although seizures persisted after temporal lobe surgery no progressive cognitive or neurologic deficit has emerged. Prominent auditory auras in each suggested a persisting epileptogenic focus in the superior temporal gyrus. The current findings expand the clinical spectrum of Rasmussen's encephalitis and suggest that chronic nonprogressive encephalitis may serve as the pathologic substrate of medically intractable temporal lobe epilepsy.

Lateralizing and localizing values of ictal onset recorded on the scalp: evidence from simultaneous recordings with intracranial foramen ovale electrodes.

PURPOSE: The value of scalp recordings to localize and lateralize seizure onset in temporal lobe epilepsy has been assessed by comparing simultaneous scalp and intracranial foramen ovale (FO) recordings during presurgical assessment. The sensitivity of scalp recordings for detecting mesial temporal ictal onset has been compared with a "gold standard" provided by simultaneous deep intracranial FO recordings from the mesial aspect of the temporal lobe. As FO electrodes are introduced via anatomic holes, they provide a unique opportunity to record simultaneously from scalp and mesial temporal structures without disrupting the conducting properties of the brain coverings by burr holes and wounds, which can otherwise make simultaneous scalp and intracranial recordings unrepresentative of the habitual EEG. METHODS: Simultaneous FO and scalp recordings from 314 seizures have been studied in 110 patients under telemetric presurgical assessment for temporal lobe epilepsy. Seizure onset was identified on scalp records while blind to recordings from FO electrodes and vice versa. RESULTS: Bilateral onset (symmetric or asymmetric) was more commonly found in scalp than in FO recordings. The contrary was true for unilateral seizure onset. In seizures with bilateral asymmetric onset on the scalp, the topography of largest-amplitude scalp changes at onset does not have localizing or lateralizing value. However, 75-76% of seizures showing unilateral scalp onset with largest amplitude at T1/T2 or T3/T4 had mesial temporal onset. This proportion dropped to 42% among all seizures with a unilateral scalp onset at other locations. Of those seizures with unilateral onset on the scalp at T1/T2, 65.2% showed an ipsilateral mesial temporal onset, and 10.9% had scalp onset incorrectly lateralized with respect to the mesial temporal onset seen on FO recordings. In seizures with a unilateral onset on the scalp at electrodes other than T1/T2, the proportions of seizures with correctly and incorrectly lateralized mesial temporal onset were 37.5 and 4.2%, respectively. Thus the ratio between incorrectly and correctly lateralized mesial temporal onsets is largely similar for seizures with unilateral scalp onset at T1/T2 (16.7%) and for seizures with unilateral scalp onset at electrodes other than T1/T2 (11.2%). The onset of scalp changes before the onset of clinical manifestations is not associated with a lower proportion of seizures with bilateral onset on the scalp, or with a higher percentage of mesial temporal seizures or of mesial temporal seizures starting ipsilateral to the side of scalp onset. In contrast, the majority (78.4%) of mesial temporal seizures showed clinical manifestations starting after ictal onset on FO recordings. CONCLUSIONS: A bilateral scalp onset (symmetric or asymmetric) is compatible with a mesial temporal onset, and should not deter further surgical assessment. Although a unilateral scalp onset at T1/T2 or T3/T4 is associated with a higher probability of mesial temporal onset, a unilateral onset at other scalp electrodes does not exclude mesial temporal onset. A unilateral scalp onset at electrodes other than T1/T2 is less likely to be associated with mesial temporal onset, but its lateralizing value is similar to that of unilateral scalp onset at T1/T2. The presence of clinical manifestations preceding scalp onset does not reduce the localizing or lateralizing values of scalp recordings.

A three-dimensional physical model of MRI noise based on current noise sources in a conductor.

Magnetic flux noise is generated by any conductor in equilibrium with a bath as a result of random fluctuating currents. A physical model of this flux noise is proposed, based on allowable current patterns in the conductor, which we describe as natural current modes. This model gives insight into the spatial characteristics of the magnetic noise which is encountered in a variety of magnetic measurements and imaging modalities such as magnetic resonance imaging (MRI).

Failed surgery for epilepsy. A study of persistence and recurrence of seizures following temporal resection.

From a series of 282 consecutive temporal resections for medically intractable epilepsy associated with mesial temporal sclerosis (MTS), dysembryoplastic neuroepithelial tumour (DNT) or non-specific pathology (NSP), 51 patients had persistent or recurrent seizures occurring at least monthly. Of these patients, 44 underwent detailed assessment of their postoperative seizures, which included clinical evaluation, interictal and ictal EEG and high-resolution MRI. Of the 20 patients with MTS in the original pathology, 14 (70%) had postoperative seizures arising in the hemisphere of the resection, the majority (12 patients) in the temporal region. Although MRI demonstrated residual hippocampus in five of these 12 patients, only one patient was considered to have seizures arising there, whilst the remainder had electroclinical evidence of seizure onset in the neocortex. In contrast, five of the MTS relapses (25%) had seizure onset exclusively in the contralateral temporal region. Among the 14 patients with non-specific pathology, relapse was also predominantly from the ipsilateral hemisphere (64%), but more relapsed from extratemporal sites compared with the MTS cases, including two with NSP who had occipital structural abnormalities. Although 70% of the 10 patients with DNT had postoperative partial seizures arising in the ipsilateral hemisphere, many (60%) had evidence of a more diffuse disorder with additional generalized seizures, cognitive and behavioural disturbance and multifocal and generalized EEG abnormalities. Nine patients (20%) had immediate postoperative seizure-free periods of at least 1 year, and seven of these had MTS in the operative specimen. Of these seven patients, four had ipsilateral temporal seizures and three had contralateral temporal seizures. Overall, few missed lesions were discovered on postoperative MRI and reoperations were performed or considered possible in a minority of cases. Despite well-defined preoperative electroclinical syndromes of temporal lobe epilepsy, many patients relapsed unexpectedly, either immediately or remotely from the time of surgery. Maturing epileptogenicity in a surgical scar was not, however, considered to be a significant primary mechanism in patients who relapsed after a seizure-free interval.

Transient ischaemic attacks: evaluation and management.

Transient ischaemic attacks (TIAs) are temporary focal cerebral or retinal deficits that resolve within 24 hours. Attention should be given to the tempo and localisation of the clinical syndrome, as multiple and hemispheric TIAs are associated with the greatest incidence of early stroke. Evaluation of TIAs depends on the clinical symptoms, physical examination and investigations. Attention should be given to clinical evidence of generalised atherosclerotic disease, as death due to the complications of ischaemic heart disease is the commonest outcome in patients with TIA. Early attention should focus on risk factor modification, with emphasis on the treatment of hypertension and smoking cessation. Antiplatelet therapy should be instituted. Aspirin is the first-line treatment but, if not tolerated, clopidogrel is effective in preventing vascular complications. Anticoagulants are generally reserved for patients with atrial fibrillation and are associated with a significant reduction of stroke risk. The use of statins is becoming more widespread, with emerging evidence of their efficacy in reducing stroke risk. The risk of stroke is greatest in the weeks following TIA and patients should be referred for carotid duplex ultrasonography. Carotid endarterectomy for symptomatic internal carotid artery high grade stenosis virtually abolishes stroke risk in that vascular territory over subsequent years. TIAs should be regarded as an emergency requiring early diagnosis and prompt referral.