Malpractice claims against radiologists. Analysis of the five-year period 1993-1997

OBJECTIVES: Landau-Kleffner Syndrome (LKS) is an epileptic syndrome characterised by a deficit in language comprehension and production, paroxysmal epileptiform activity in the posterior temporal leads, and by the inconsistent presence of epileptic fits. Its interest lies in the fact that it stands as a model for the study of interference of epileptiform activity on cognitive function, although the pathophysiology of the decline in language skills that follows its onset has not yet been clarified. METHODS: We have recorded spike-triggered auditory evoked responses in a group of 6 children with LKS, to investigate whether the occurrence of individual EEG paroxysms is able per se to induce a decline in the response of the auditory cortex. RESULTS: Results have indicated that left hemisphere spikes are associated with a greater reduction in amplitude and an increase in latency of the NI, than spikes occurring in the right hemisphere. No stable change in the evoked response has been detected outside of the EEG paroxysm. CONCLUSIONS: We postulate EEG interictal activity is able to induce impairment in processing auditory information and that this may play a role in the pathogenesis of language deficit in LKS.     

Epileptiform electroencephalographic patterns

Electroencephalography (EEG) is the most useful test for assessment of patients with epilepsy. It can help establish the diagnosis of epilepsy and determine the type of seizure disorder and its site of origin. Epileptiform abnormalities in the EEG tracing may be focal or generalized. The main types of focal epileptiform discharges arise from the temporal, frontal, occipital, centroparietal, centrotemporal, and midline regions of the brain. Generalized epileptiform discharges consist of the 3-Hz spike-and-wave, slow spike-and-wave, atypical spike-and-wave, paroxysmal fast activity, and hypsarrhythmic patterns. Status epilepticus is manifested by continuous epileptiform discharges or recurrent seizure activity without interim recovery, which can occur in a generalized or focal manner. Benign epileptiform variants unassociated with seizures can also be present in the EEG. Included in this category are the "14 & 6" positive bursts, small sharp spikes, wicket waves, 6-Hz spike-and-wave discharges, and rhythmic temporal theta activity. The EEG findings should be interpreted in the context of the overall clinical picture.     

Decision making in CPR: attitudes of hospital patients and healthcare professionals

The medical records of 478 SLE patients were reviewed. Ninety-five patients (19.9%) with a history of seizures were identified. EEG reports were available on 62. EEGs were interpreted as normal in 8 (12.9%) and abnormal in 54 (87.1%). Abnormal EEGs were reviewed for the presence of unilateral and bilateral abnormalities. Left hemisphere abnormalities were identified in 43 (79.6%), right hemisphere abnormalities in 4 (7.4%), and bilateral abnormalities in 7 (13.0%) patients with SLE. Abnormalities included theta and delta slowing and sharp wave activity. In 32 of the 43 (74.4%) patients with left hemisphere abnormalities, the abnormalities were localized to the left temporal leads. These findings suggest selective damage to the left temporolimbic region in patients with SLE.     

The effect of propofol on the electroencephalogram of patients with epilepsy

The effect of propofol on the electroencephalogram (EEG) in patients with epilepsy is still unclear. Case reports with electroencephalographic documentation highlight pro- and anticonvulsant effects and beta activation of the EEG. This prospective study sought to determine the effect of propofol in 17 patients undergoing cortical resection for intractable epilepsy. Each patient received 2 mg/kg of propofol intravenously and the EEG was recorded from chronically implanted subdural electrodes placed during a previous craniotomy. Frequency of interictal spikes, time to burst suppression, and appearance of beta activation were recorded. The median frequency of interictal spikes decreased significantly from 2 spikes/min before to 0 spikes/min after propofol (P = 0.001). Seizure activity did not increase after propofol. Profound burst suppression and an increase in beta activity were noted consistently. The use of propofol in patients with epilepsy seems to be safe but may interfere with the recording of EEG spikes.     

A reconsideration of bilateral language representation based on the intracarotid amobarbital procedure

Hemispheric language dominance was established for 368 epilepsy surgery candidates based on results of objective language performance during the intracarotid amobarbital procedure. Eight-three percent of patients were found to be left hemisphere dominant, while six percent were right dominant, and eleven percent demonstrated some degree of bilateral language representation. Bilateral patients were grouped according to modality-specific patterns of language performance in each hemisphere, with a majority demonstrating left hemisphere superiority in overall language processing. Variables affecting atypical language development are reviewed and results are considered in the context of previous research.     

Case of simple partial status epilepticus in occipital lobe epilepsy misdiagnosed as migraine: clinical, electrophysiological, and magnetic resonance imaging characteristics

An 31-year-old man had a unique form of occipital lobe epilepsy. Since age 13 years, he has had episodes of simple partial status epilepticus (SE) occurring twice a month. These typically consisted of elementary visual hallucinations of flashing lights obscuring his left visual field for a period of 2 days, associated with a severe frontal headache initially diagnosed as migraine. These episodes of simple partial SE then evolved to a complex partial seizure (CPS) or secondarily generalized seizure. There were unique EEG features, including: (a) the perception of a flash of light in the left visual field with a single sharp/slow wave discharge over the right occipital lobe, (b) right occipital lobe epileptiform activity during the prolonged aura, and (c) an abnormal response to photic stimulation, with occipital lobe discharges during low rates of stimulation (3-5 Hz), time-locked to the stimulus. High-resolution magnetic resonance imaging (MRI) with quantitative morphometry demonstrated that the right hemisphere and right caudate nucleus were smaller than those on the left. An abnormal gyral pattern was also noted over the right parietal region. Occasionally, distinguishing occipital lobe epilepsy from migraine may be difficult.     

Thyroid function in lead smelter workers: absence of subacute or cumulative effects with moderate lead burdens

The electroencephalographic abnormalities seen in Landau-Kleffner syndrome (LKS) (language deterioration) are non-specific, and consist of a variety of epileptiform discharge patterns including continuous slow spike-wave discharges during sleep, focal sharp waves with spikes, and centrotemporal (rolandic) spikes. Similarly, the EEG abnormalities seen in autistic epileptiform regression (language and social/behavioral deterioration) are non-specific and overlap with those seen in LKS. By contrast, distinct epilepsy syndromes in otherwise normal children occur in the EEG-defined benign focal epilepsies of childhood. Occipital spikes or spike-wave present either in the older child with visual symptoms and headache or in the younger child with autonomic symptoms followed by brief or prolonged partial motor seizures. Seven young children (five from a consecutive series of 42) presenting clinically with autism or autistic regression and possible or definite seizures, whose EEGs revealed occipital spikes or spike-wave characteristic of the benign epilepsies, are reported. Although occipital spikes are commonly seen in young children as an age-dependent EEG-defined benign focal epilepsy, their high frequency in this population with cognitive difficulties suggests a possible causal relation. The effects of the epileptiform discharge on cognitive functioning presumably reflect extension into temporal and parietal lobes, rather than occipital disturbances per se.     

"Cavernous sinus EEG": a new method for the preoperative evaluation of temporal lobe epilepsy

PURPOSE: In presurgical evaluation of temporal lobe epilepsy (TLE), invasive methods are necessary if results of various noninvasive methods are not sufficiently convergent enough to identify the epileptogenic area accurately. To detect the epileptiform discharges originating specifically from the mesial temporal lobe, we applied the cavernous sinus catheterization technique. METHODS: We placed Seeker Lite-10 guide wire electrodes into bilateral cavernous sinus through the internal jugular veins to record EEG (cavernous sinus EEG) in 6 patients with intractable TLE. Scalp EEG was simultaneously recorded in all 6 and electrocorticogram (ECoG) was also recorded in 4. RESULTS: The cavernous sinus EEG demonstrated clear epileptiform discharges, sometimes even when they were absent on the simultaneously recorded scalp EEG. The epileptiform discharges recorded from the cavernous sinus electrodes were specifically associated with those in the mesial temporal region on ECoG. Ictal EEG pattern originating from mesial temporal lobe was also clearly documented on the cavernous sinus EEG. CONCLUSIONS: This new, semi-invasive method of identifying epileptogenic areas can detect the epileptiform discharges specifically arising from the mesial temporal lobe; it is as useful as or complements the invasive techniques such as foramen ovale or depth recording.     

Surgical management of aortic regurgitation associated with ventricular septal defect

The intracarotid amobarbital procedure was carried out in 8 male and 7 female candidates to temporal lobectomy, and a female candidate to frontal lesionectomy, aged 18-50 (mean 32.5) years. Language and memory were tested after injection in each hemisphere. Both were measured by the Montreal procedure. In 9 patients language and memory were evaluated with the Seattle procedure too. In 12 patients the left hemisphere was dominant for language; three had bilateral dominance. In 1 patient the Seattle procedure demonstrated the dominant hemisphere by relatively slowness of speech during the drug effect in the left hemisphere. Memory was defined to be in the left hemisphere in 12 patients, in the right in 2, bilateral in 1 and in another lateralization was not possible. In 1 patient memory dominance was determined by the Montreal protocol alone because of lack of cooperation. These early results indicate that the methods may be complementary for determination of language and memory dominance in epilepsy surgery candidates.     

Daily variations in pineal melatonin concentrations in inbred and outbred mice

Magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT) and magnetic resonance spectroscopy (MRS) were successively recorded in a 3-year-old girl with the acute hemiplegia syndrome. She was admitted to our hospital with complaints of fever, loss of consciousness and right side dominant clonic convulsions evolving into status epilepticus, and then recovered with sequelae of aphasia and right hemiparesis. Electroencephalography showed a generalized slow rhythm at the onset, and very low activities on the left hemisphere in the follow-up records. Brain CT and MRI revealed edema of the left hemisphere initially, followed by left side dominant brain atrophy. No cerebral vascular lesion was detected by magnetic resonance angiography. N-Isopropyl-[123I]-iodoamphetamine SPECT showed marked hypoperfusion of the left hemisphere accompanied by crossed cerebellar diaschisis. MRS at the initial stage detected decreased N-acetyl-aspartic acid and increased lactic acid signals in the bilateral hemisphere, which subsequently normalized only on the right side. These findings suggested brain damage and neural cell death in the left cerebral hemisphere, caused by acute encephalopathy. SPECT and MRS are useful new techniques to study the pathophysiology of the acute hemiplegia syndrome.     

Limbic ERPs predict verbal memory after left-sided hippocampectomy

Surgical removal of the dominant medial temporal lobe regions runs a considerable risk of verbal memory deficits which may be compensated for postoperatively by corresponding regions in the non-dominant medial temporal lobe. We examined this possibility by recording event-related potentials (ERPs) to words from the medial temporal lobes of patients with left-sided temporal lobe epilepsy (TLE) undergoing presurgical evaluation. N400 amplitudes in the right anterior medial temporal lobe predicted the postoperative verbal recall performance of individual patients with surprising accuracy, indicating that intracranial recordings can be used to quantify the functional capacities of the right hemisphere that can compensate for the verbal memory deficits after loss of medial temporal lobe structures in the left hemisphere.     

EEG video recording

We analyse EEG data from video-EEG recordings of 24 patients, selected among the 63 with "pure" temporal lobe epilepsy. As to interictal EEG features, 62.5% of patients show a less regular background activity on the affected side, in 70% of patients slow waves are either localised or lobar, while in 58% are spikes. Slow waves and spikes have the same well-defined localisation in 37.5% of the patients. Ictal recordings show an initial EEG pattern with high localising value (low-voltage fast activity, flattening or slow waves interruption) in 74/121 seizures (61%). Five out of these 24 patients were operated on without invasive recordings on the basis of ictal video-EEG data. In the 19 patients left, video-EEG ictal informations were used for the planning of the stereo-EEG exploration.     

Factors associated with epileptiform EEG patterns in Nigerian epileptics

We reviewed electroencephalographic (EEG) records of 626 epileptic patients for the frequency of epileptiform patterns (EP). The purpose of this study was to determine the factors determining the occurrence of EP. Epileptiform pattern was detected in 46% of patients studied. The occurrence of EP was associated with age, seizure type, longer duration of epilepsy, and proximity of EEG examination to last attack. We found no association between seizure frequency, medication status at EEG examination and the occurrence of EP. The yield of diagnostically useful findings in the interictal EEG would be increased if the test is performed as close as possible to the last seizure.     

MRI-radiofrequency tissue tagging in patients with aortic insufficiency before and after operation

We examined the relation between language dominance and regional cerebral blood flow (rCBF) during the intracarotid amobarbital procedure (IAP). A previous report limited to three patients suggested that dominant rather than nondominant hemisphere IAP may have a differential effect on rCBF. Behavioral assessment during the IAP also suggests that dominant hemisphere injection results in a differential effect on memory and affective symptoms rather than nondominant injection. Thirteen patients were assessed using single-photon emission CT (SPECT) brain imaging during both left and right IAP. The SPECTs were coregistered with the individual's MRI. Changes in rCBF during each IAP were compared with the patient's baseline SPECT. Nine patients had left hemisphere dominance, two were right dominant, and two had bilateral speech representation. In the left dominant subjects, left-hemisphere injection had a consistently greater effect on rCBF than right-hemisphere injection in the anterior (p < 0.005) and posterior (p < 0.01) temporal neocortex. There was also a trend for greater hypoperfusion in the frontal lobe of the left hemisphere. rCBF in the ipsilateral hippocampus was not significantly different after each injection (p > 0.05). In the two patients with right hemisphere speech, the reverse pattern was seen, with greater hypoperfusion after right (dominant) hemisphere injection. There was no consistent asymmetry in the two patients with bilateral speech. Dominant hemisphere IAP results in significantly greater hypoperfusion than does nondominant injection. These data provide a physiologic basis for behavioral differences noted after dominant versus nondominant IAP.     

Molecular cloning and characterization of a recombinant Histoplasma capsulatum antigen for antibody-based diagnosis of human histoplasmosis

We recorded simultaneous multichannel electroencephalogram (EEG) and magnetoencephalogram (MEG) in four children with partial epilepsy. Sources of averaged spikes were modelled with current dipoles. Of 10 spike averages obtained, three peaked simultaneously in MEG and EEG, and in seven averages, the MEG peak preceded the main EEG peak by 9-40 ms. A small positive early EEG signal coincided with the MEG peak in six asynchronous spikes. The simultaneous MEG and EEG spikes originated within 5-23 mm, while sources of asynchronous peaks were 12-67 mm apart. We conclude that non-identical neurone currents underlie the MEG and EEG signals, and emphasize the importance of modelling early phases of EEG spikes when localizing interictal epileptic zones.     

Electroencephalographic signs of compensatory reactions following stroke with location of the focus in the right and left cerebral hemispheres

The authors studied 41 patients with acute disorders of cerebral circulation, a focus in the right hemisphere and 14 with foci in the left hemisphere. The traits of compensatory reactions were studied according to the background and functional EEG, depending upon the severity, stage, localization and lateralization of focal vascular brain lesions. The authors indicate to a rigidity of clinical and EEG changes in patients with right hemispheric localization of the focus which is explained by the authors by disturbances of the higher cortical functions in these patients.     

Transgenerational effects of abusive violence on the children of Vietnam combat veterans

The present study was aimed at the comparative assessment of electrophysiological and clinical data in persons (155 right-handed men) who took part in the Chernobyl clean-up in different periods after radiation. Dynamic evaluation of psychoneurological disorders revealed the growth of incidence and severity of cerebrovascular disturbances accompanied by the signs of organic symptoms' aggravation and encephalopathy in longer periods after radiation. The results of neuropsychological examination also showed the deterioration of patients' state manifested as growth of fatigue, cognitive defects, and emotional impairments. Analysis of the EEG parameters, including power and coherence mapping and 3-d dipole source localization analysis demonstrated the increasing number of patients with the most severe forms of EEG pathology: the "plane" type in combination with fast paroxysmal (beta-band) and slow forms of activity from 45% in 1990-92 to 63% in 1997. The "hypersynchronization" type of EEG activity was typical for the earlier period accompanied by the dominance of the pathological forms of EEG activity in mediobasal structures of the left hemisphere, and brainstem zones vs. diencephalon and the right hemisphere. The later period was characterized by decreasing coherence in symmetrical frontal and front-temporal areas of the left hemisphere, while in the early period the hypersynchronization prevailed in symmetrical central areas and in the right hemisphere. The evidence were obtained to a disconnection between the brain hemispheres. We suppose that the progressive involvement of structures of the limbic-reticular complex (especially, brainstem, mediobasal structures, and white matter) into the pathological process occurs with time in participants of clean-up of the Chernobyl disaster consequences.     

A study of visual processes in a case of interhemispheric disconnexion

A 75-year-old right-handed woman, after a probable cerebral infarct, developed an irregular constriction of the visual fields, a left-sided agraphia, and an anomia for objects in the left hand. Subsequent testing demonstrated an inability to name, though ability to recognize, letters and objects flashed in the homonymous left visual field. An inter-hemispheric disconnexion syndrome was inferred from these findings. The present publication concerns mainly the visual aspects of this disconnexion syndrome. Tasks were devised to test the abilities of the major and minor hemisphere: (a) the left hemisphere demonstrated a complete dominance for language expression and an incomplete dominance for written language comprehension; (b) the right hemisphere appeared to be dominant for some visuo-spatial tasks including number comprehension; (c) when the hemispheres were given contradictory visual informations on a non-verbal task (chimeric stimuli) there was a predominance of the right hemisphere. The right hemisphere appeared able to process complex information. Specialization of functional activities in each hemisphere is briefly discussed.     

Neuropsychology and pathology of the cerebral cortex

In all clinics we are faced with questions about certain aspects of cerebral dominance. We consider first the problem of recognition of faces where the right hemisphere plays a leading role. However, the disorders manifesting that function appear only bilateral lesions. This suggests that the left hemisphere participates in this process. The reception of language raises a problem which is analogous with the preceding: we propose the participation of both hemispheres in this activity: the left hemisphere is dominant in the analysis of phonemes and syntax, the right hemisphere seems implicated above all in the processing of prosodic aspects--in particular intonations and individual features of the voice.     

A particular type of epilepsy in patients with congenital hemiparesis associated with polymicrogyria or unilateral pachygyria

INTRODUCTION: Magnetic resonance has permitted the recognition of cortical dysplasias in patients with congenital hemiparesia and epilepsy. OBJECTIVE: To study the clinic-EEG characteristics and course of epilepsy in patients with congenital hemiparesia and unilateral polymicrogyria. METHODS AND RESULTS: We analyzed the clinical histories of 11 patients seen between 1990 and 1996. We studied 6 girls and 5 boys aged between 5 and 13 years, with a follow-up period of from 1 to 6 years. The epilepsy began at between 1 and 6 years old with partial motor seizures. On EEG there were frontotemporal spikes in 9 cases, temporooccipital in 1 and parieto-occipital in another. All 11 patients had hemiparesia, with slight mental retardation in 9 patients and moderate mental retardation in 2. The CT/MR brain scan showed unilateral polymicrogyria. At between 2 and 8 years of age, all 11 patients developed subintrant atonic crises with a pseudo-ataxic gait, absences in 7 patients and myoclonia in 3. Awake EEG showed bilateral asymmetrical spikes. During sleep 7 patients had continuous spikewave discharges and 4 had frequent asymmetrical bilateral spikes. Four patients relapsed. Five patients are free of crises, five have sporadic crises and one continues to have daily crises. CONCLUSIONS: These patients had hemiparetic cerebral paralysis, slight mental retardation and epilepsy. At about the age of 6 a peculiar electro-clinical condition developed. Response to treatment was satisfactory, although the follow-up period is still not long.