VMAT-IGRT Hypofractionated Radiotherapy for Locally Advanced Thyroid Cancer in Resource-Limited Settings: A Retrospective Report from Bolivia

PURPOSE/OBJECTIVE(S)

This study evaluated the efficacy and safety of hypofractionated external beam irradiation with VMAT-IGRT in patients with locally advanced thyroid cancer (LATC) who are ineligible for surgery or I-131 in a resource-limited setting such as Bolivia.

MATERIALS/METHODS

Thirty-three patients were treated with H-VMAT-IGRT between August 2018 and November 2022. Axial CT images were acquired every 3 mm from the base of the skull to the middle of the chest. GTV was determined based on contrast-enhanced tumor on T1 MRI or CT scans. CTV 55 Gy at 2.75 Gy was defined based on visible residual tumor and included dissected nodal stations with pathologically positive nodes. CTV 44 at 2.2 Gy for non-dissected nodal stations with low risk of recurrence, we escalated the dose up to 60 Gy at 3 Gy for small tumors up to 20 cc. PTVs were created by adding a 0.3 cm margin around CTVs, with a reduced margin of minus 3-5 mm for critical organs such as esophagus, pharynx, and brachial plexus. Equivalent dose in 2Gy (EQD2 10-3) was reported for tumor control and OAR constraints. Acute toxicity was reported according to RTOG criteria, and response to treatment was assessed at baseline, end of treatment, and every third month thereafter.

RESULTS

The mean time since last follow-up was 24 months (r: 8-40). Patients were 80% female and 20% male. The mean age was 50 years (r: 29-72). Local recurrence was treated in 52% (13) of patients and LATC in 48% (12). Papillary carcinomas accounted for 68% of patients, followed by anaplastic (24%) and follicular (8%) carcinomas. Tumors were classified according to the AJCC classification. Of the patients treated for LATC, 25% were at stage II, 25% at stage III, 16.67% at stage IVA, and 33.33% at stage IVB. Among patients treated for local recurrence, the initial stage before progression was stage I in 61.5%, stage II in 30.8%, and stage IVA in 7.7%. The median PTV was 383.8 cc (r: 51.7 - 627.3) and the median CTV55 was 189.2 cc (r: 39.6 - 519.8). Grade 1 (10%), Grade 2 (90%) dysphagia, Grade 1 (40%), Grade 2 (60%) acute pharyngeal mucositis, and no Grade 3 acute toxicity were observed. No reports of chronic upper damage GI, 30% xerostomia G2. Two-year local control was 70% and overall survival was also 70%.

CONCLUSION

We suggest that reducing treatment duration while maintaining efficacy is particularly beneficial in resource-limited areas with a shortage of trained personnel and overburdened treatment centers. We report good local control rates with no detrimental effects on quality of life with hypofractionation. No evidence of delayed damage, such as spinal cord dysfunction, mandibular osteoradionecrosis, or brachial plexopathy, was noted. We emphasize the importance of using VMAT with IGRT for reliable and accurate daily treatment of the target area, while minimizing side effects. However, these results should be confirmed with a larger sample of patients.

Effects of Cold Pressed Chia Seed Oil Intake on Hematological and Biochemical Biomarkers in Both Normal and Hypercholesterolemic Rabbits

Most of the studies on the beneficial effects of chia have been conducted with its seeds. There is less evidence about the effects of cold pressed chia seeds oil on hypercholesterolemia-induced alterations. Thus, this study investigated the effects of cold pressed chia seed oil supplementation on certain hematological and biochemical biomarkers in both normal and hypercholesterolemic rabbits. Thirty two male rabbits were assigned to four different groups and fed on: 1) a regular diet (CD), 2) CD supplemented with 10% chia oil, 3) CD supplemented with 1% cholesterol, 4) CD supplemented with 1% cholesterol and 10% chia oil. After six weeks of dietary interventions, mean arterial blood pressure and visceral fat were measured and blood samples were analyzed for lipid profiles and hematological parameters while erythrocyte membranes and retroperitoneal fat were analyzed for fatty acids composition and biochemical biomarkers. Dietary intervention with chia oil achieved control of the hypercholesterolemia-induced increase of mean arterial blood pressure, neutrophil to lymphocytes ratio, erythrocyte membrane fluidity, and improved erythrocyte morphological alterations. With regard to inflammatory biomarkers, chia oil supplementation reduced omega-6/omega-3 polyunsaturated fatty acids ratios and arachidonic/linolenic fatty acids ratios both in erythrocytes and fat from normal and hypercholesterolemic rabbits. The increase of linolenic fatty acid into the retroperitoneal fat was about 9 times higher than its respective controls. These results provide support for the potential health benefits of chia oil intake on hypercholesterolemia-associated clinical, hematological and biochemical alterations.

Oral administration of Zuccagnia punctata extract improves lipid profile, reduces oxidative stress and prevents vascular dysfunction in hypercholesterolemic rabbits

BACKGROUND

The consumption of flavonoids has been shown to prevent cardiovascular diseases including atherosclerosis. In this sense, in a recent in vitro study we demonstrated that a rich in flavonoids extract from Zuccagnia punctata has beneficial effects on vascular function in aorta from hypercholesterolemic rabbits.

PURPOSE

The aim of this study was to evaluate the ability of a hydroalcoholic extract from Z.puncata (ZpE) to prevent alterations induced by high cholesterol diet in rabbits.

METHODS

The major components of the ZpE, flavonoids, were analyzed by using a validated reversed phase HPLC method. Rabbits were separated in five groups: fed standard chow (CD); CD orally administrated 2.5 mg, 5 mg or 10 mg GAE/day ZpE (ZpE- CD); fed 1% cholesterol-enriched chow (HD); HD orally administrated 2.5 mg GAE/day ZpE (ZpE-HD); HD orally administrated 2.5 mg rosuvastatin/day (Ro-HD). All diets were administrated by 6 weeks. Body weights (BW), mean blood pressure (MAP), heart rate (HR), visceral abdominal fat (VAF), organ weight (heart, kidney, liver) and vascular morphology were determined. Total cholesterol (TC), triglycerides (TG), fasting glucose (FG), aspartate amino transferase (AST), alanine amino transferase (ALT), bilirubin, creatinine, thiobarbituric acids reactive substances (TBARS) and glutathione reduced/oxidized index were measured in serum. Abdominal aorta was excised and vascular function was assessed by acetylcholine and sodium nitroprusiate relaxation and contractile response to norepinephrine and angiotensin II.

RESULTS

The major compounds of ZpE identified were chalcones: 2',4'-dihydroxy-3'-methoxychalcone and 2',4'-dihydroxychalcone. Oral treatment with ZpE reduced MAP, TC, TG, TBARS, aortic intima/media ratio and increased glutathione reduced/oxidized index in HD rabbits. No differences were found in AST, ALT, bilirubin or creatinine. Acetylcholine relaxation was normalized and contractile response to norepinephrine and angiotensin II was reduced in ZpE-HD.

CONCLUSION

Oral administration of ZpE as natural product in the prevention of cardiovascular disease related with hypercholesterolemia and endothelial dysfunction is very promising.

Differences in globus pallidus neuronal firing rates and patterns relate to different disease biology in children with dystonia

BACKGROUND

The pathophysiology underlying different types of dystonia is not yet understood. We report microelectrode data from the globus pallidus interna (GPi) and globus pallidus externa (GPe) in children undergoing deep brain stimulation (DBS) for dystonia and investigate whether GPi and GPe firing rates differ between dystonia types.

METHODS

Single pass microelectrode data were obtained to guide electrode position in 44 children (3.3-18.1 years, median 10.7) with the following dystonia types: 14 primary, 22 secondary Static and 8 progressive secondary to neuronal brain iron accumulation (NBIA). Preoperative stereotactic MRI determined coordinates for the GPi target. Digitised spike trains were analysed offline, blind to clinical data. Electrode placement was confirmed by a postoperative stereotactic CT scan.

FINDINGS

We identified 263 GPi and 87 GPe cells. Both GPi and GPe firing frequencies differed significantly with dystonia aetiology. The median GPi firing frequency was higher in the primary group than in the secondary static group (13.5 Hz vs 9.6 Hz; p=0.002) and higher in the NBIA group than in either the primary (25 Hz vs 13.5 Hz; p=0.006) or the secondary static group (25 Hz vs 9.6 Hz; p=0.00004). The median GPe firing frequency was higher in the NBIA group than in the secondary static group (15.9 Hz vs 7 Hz; p=0.013). The NBIA group also showed a higher proportion of regularly firing GPi cells compared with the other groups (p<0.001). A higher proportion of regular GPi cells was also seen in patients with fixed/tonic dystonia compared with a phasic/dynamic dystonia phenotype (p<0.001). The GPi firing frequency showed a positive correlation with 1-year outcome from DBS measured by improvement in the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS-m) score (p=0.030). This association was stronger for the non-progressive patients (p=0.006).

INTERPRETATION

Pallidal firing rates and patterns differ significantly with dystonia aetiology and phenotype. Identification of specific firing patterns may help determine targets and patient-specific protocols for neuromodulation therapy.

FUNDING

National Institute of Health Research, Guy's and St. Thomas' Charity, Dystonia Society UK, Action Medical Research, German National Academic Foundation.

Clinical manifestations and coronary artery disease risk factors at diagnosis of systemic lupus erythematosus: data from an international inception cohort

Systemic Lupus International Collaborating Clinics (SLICC) comprises 27 centres from 11 countries. An inception cohort of 918 SLE patients has been assembled according to a standardized protocol between 2000 and 2006. Clinical features, classic coronary artery disease (CAD) risk factors, as well as other potential risk factors were collected. Of the 918 patients 89% were females, and of multi racial origin. Less than half the patients were living in a permanent relationship, 58% had post secondary education and 51% were employed. Eight percent had family history of SLE. At enrolment, with at mean age of diagnosis of 34.5 years, a significant number of patients already had CAD risk factors, such as hypertension (33%) and hypercholesterolemia (36%). Only 15% of the patients were postmenopausal, 16% were current smokers and 3.6% had diabetes at entry to the SLICC-RAS (Registry for Atherosclerosis). A number of patients in this multi-racial, multi-ethnic inception cohort of lupus patients have classic CAD risk factors within a mean of 5.4 months from diagnosis. This cohort will be increased to 1500 patients to be followed yearly for 10 years. This will provide a unique opportunity to evaluate risk factors for accelerated atherosclerosis in SLE. Lupus (2007) 16, 731—735.

[Congenital insensitivity to pain: clinical and neurophysiological study in three sisters of a Moroccan family]

Congenital insensitivity to pain is a rare hereditary sensory and autonomic neuropathy (HSAN). This disorder is an autosomal recessive condition: since 1996, mutations attributed to this entity have been found in the neurotrophin tyrosine-kinase gene receptor on chromosome 1. The authors report 3 cases of congenital insensitivity to pain. In these 3 sisters of consanguineous parents, the clinical investigation showed total absence of pain and temperature sensations with preservation of all other sensory modalities, mental retardation, but in contrast to HSAN type IV, there was no anhidrosis. The neurophysiological investigation revealed an isolated axonal sensory polyneuropathy in the 3 patients. The clinical and neurophysiological investigations were normal in both parents and the brother. The physiopathology of this entity is discussed. We suggest a particular form of HSAN type IV with preservation of transpiration or a new entity of congenital insensitivity to pain, which should be analyzed genetically.

Performance of the international classifications criteria for autoimmune hepatitis diagnosis in Mexican patients

The revised score of the International Autoimmune Hepatitis Group (R-IAIHG) and the simplified criteria (SC) are used for diagnosis of autoimmune hepatitis (AIH). Our aim is to evaluate the performance of these classifications to differentiate AIH from other autoimmune liver diseases. The frequency of diagnosis of definite AIH was similar both by the R-IAIHG and the SC systems (41% versus 40%), whereas diagnosis of probable AIH was made more commonly by the R-IAIHG than the SC (59% versus 29%), and 23 patients that have been graded as definite (n = 7) or probable (n = 16) AIH by the R-IAIHG had non-diagnostic scores by the SC system. The scoring systems rendered concordant diagnosis of definite (n = 15) and probable (n = 13) AIH in 28/73 patients (38%). Discordant diagnoses of AIH were rendered in 45/73 patients (62%). The R-IAIHG exhibited a sensitivity of 95%, specificity of 90%, and positive predictive value (PPV) and negative predictive value (NPV) of 93% for both. On the other hand, the SC had a lower sensitivity (65%) but a higher specificity (100%), PPV of 100%, and NPV of 68%. In conclusion, both international scoring systems diagnosed the same number of cases as definite AIH. The R-IAIHG showed a higher sensitivity in diagnosing AIH, whereas the SC showed a higher specificity. SC are easier to apply at the bedside and exclude more patients that could have a different etiology.

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.

Multiple subpial transection in Landau-Kleffner syndrome

We have considered multiple subpial transection (MST) as a treatment option for Landau-Kleffner syndrome (LKS) for the past 6 years. The effect of this technique on language and cognitive ability, behaviour, seizures, and EEG abnormalities is analysed here. Five children (4 males, 1 female; aged 5.5 to 10 years) underwent MST with sufficiently detailed pre- and postoperative data for analysis. Behaviour and seizure frequency improved dramatically after surgery in all children. Improvement in language also occurred in all children, although none improved to an age-appropriate level. All five had electrical status epilepticus in sleep (ESES) before surgery, which was eliminated by the procedure. One child has had an extension of his MST due to the recurrence of ESES and accompanying clinical deterioration with good effect. An attempt is made to set the effect of MST against the natural history of the condition. MST is an important treatment modality in LKS, although the timing of this intervention and its effect on final language outcome remains to be defined.

Relevance of residual histologic and electrocorticographic abnormalities for surgical outcome in frontal lobe epilepsy

PURPOSE

To estimate the significance of residual electrocorticographic and neuropathologic abnormalities on seizure control after surgery for frontal lobe epilepsy with the purpose of determining their relevance in deciding the extent of the surgical procedure.

METHODS

The presence of epileptiform discharges in intraoperative electrocorticograms (ECoGs) and the nature and extent of neuropathologic abnormalities were reviewed for 35 patients who underwent frontal lobe resections for the treatment of epilepsy at our institution. The relations between surgical outcome and presence of the following features were studied: (a) presence of abnormal tissue at the limits of the resection; (b) presence of sporadic spikes and seizure patterns in the preresection ECoG; (c) their abolition in the postresection ECoG; and (d) the topography of residual discharges with respect to the margins of the resection.

RESULTS

On neuropathologic examination, 18 patients showed focal cortical dysplasia (CD), and 17 showed other abnormalities (non-CD). Ten CD patients and 11 non-CD patients experienced a favourable outcome. Seizure patterns were significantly more common in patients with focal cortical dysplasia than in those without, with a sensitivity of 94% and a specificity of 75%. Abolition of seizure patterns was associated with a favourable surgical outcome (p = 0.031). Abolition of sporadic spikes or their presence in the postresection ECoG did not influence outcome. There was no clear relation between outcome and location of residual sporadic discharges. Seizure patterns persisted in the postresection ECoG in three CD patients, were located at the margins of the resection in all three, and these patients had a poor outcome. Incomplete removal of abnormal tissue was not associated with a poorer outcome in either patient group or in the complete sample.

CONCLUSIONS

Seizure patterns were significantly more common in patients with cortical dysplasia, and their abolition on postresection ECoG recordings was associated with a favourable surgical outcome. Persistence of sporadic ECoG spikes and incomplete removal of histologic abnormalities did not affect outcome significantly.

Sensitivity of recordings at sphenoidal electrode site for detecting seizure onset: evidence from scalp, superficial and deep foramen ovale recordings

OBJECTIVES

Some authors have recently stressed that the position of the tip of sphenoidal electrodes plays a crucial role in their efficacy in detecting ictal onset. An opportunity to test this hypothesis is provided by recordings from the most superficial contacts of foramen ovale (FO) electrode bundles because these contacts are located at the FO, in a position equivalent to that of optimally located sphenoidal electrodes. To simplify wording, recordings obtained by superficial FO electrodes will hereafter be called sphenoidal recordings, although they have not been obtained with standard sphenoidal electrodes. The sensitivities of simultaneous scalp and sphenoidal recordings for detecting ictal onset have been compared with each other, and with a 'gold standard' provided by simultaneous deep intracranial FO recordings from the mesial aspect of the temporal lobe.

METHODS

Three hundred and fourteen seizures obtained from 110 patients under telemetric presurgical assessment for temporal lobe epilepsy have been studied. Scalp electrodes included anterior temporal placements. All scalp electrodes were considered when identifying seizure onset but the anterior temporal electrodes were most frequently involved.

RESULTS

Ictal onset time at sphenoidal and scalp recordings: initial ictal changes appeared simultaneously in scalp and sphenoidal recordings in 123 seizures (39.2%). Initial changes occurred earlier in sphenoidal recordings in 63 seizures (20.1%), whereas they were seen earlier on the scalp in 76 seizures (24.2%). Artefacts prevented the comparison between sphenoidal and scalp recordings in 16 seizures (5.1%) and no ictal changes were seen on the scalp and/or sphenoidal recordings in 36 seizures (11.5%). In most of the 63 seizures where ictal changes appeared earlier in sphenoidal recordings, a delayed ipsilateral scalp onset was seen as the signal amplitude increased or scalp changes could be identified retrospectively on the scalp with an onset which appeared simultaneous and ipsilateral to the initial sphenoidal changes. Sphenoidal recordings supplied additional information when compared to scalp recordings in only 22 seizures (7%): in 5 seizures with artefacts on the scalp, in 6 seizures with no changes on the scalp and in 11 seizures with discrepant laterality at onset. Congruence in laterality with respect to deep intracraneal FO recordings: of the 61 seizures with unilateral onset on the scalp, onsets at sphenoidal recordings and deep FO electrodes were ipsilateral in most cases. In only 3 of these 61 seizures (4.9%), sphenoidal recordings lateralized ipsilateral to the deep FO electrodes in the presence of a contralateral onset on the scalp. In 14 among the 122 seizures (11.5%) with bilateral asymmetrical onset on the scalp, sphenoidal recordings lateralized seizure onset ipsilateral to the deep FO electrodes in the presence of a contralateral scalp onset. Thus, when compared with scalp EEG, sphenoidal recordings increased laterality congruence with respect to deep FO electrodes in 17 seizures (5.4%).

CONCLUSIONS

Extracranial electrodes located next to the FO at the sphenoidal electrode site yield an improvement over suitable surface electrodes in the identification of ictal onset in only 5.4-7% of seizures. Such improvement derives from the fact that the low amplitude signals often seen at seizure onset may show higher amplitude on sphenoidal than on scalp recordings.

A simple algorithm for a digital three-pole Butterworth filter of arbitrary cut-off frequency: application to digital electroencephalography

Algorithms for low-pass and high-pass three-pole recursive Butterworth filters of a given cut-off frequency have been developed. A band-pass filter can be implemented by sequential application of algorithms for low- and high-pass filters. The algorithms correspond to infinite impulse-response filters that have been designed by applying the bilinear transformation to the transfer functions of the corresponding analog filters, resulting in a recursive digital filter with seven real coefficients. Expressions for filter coefficients as a function of the cut-off frequency and the sampling period are derived. Filter performance is evaluated and discussed. As in the case of their analog counterparts, their transfer function shows marked flattening over the pass band and gradually higher attenuation can be seen at frequencies above or below the cut-off frequency, with a slope of around 60 dB/decade. There is a 3 dB attenuation at the cut-off frequency and a gradual increase in phase shift over one decade above or below the cut-off frequency. Low-pass filters show a maximum overshoot of 8% and high-pass filters show a maximum downwards overshoot of approximately 35%. The filter is mildly under-damped, with a damping factor of 0.5. On an IBM 300GL personal computer at 600 MH with 128 MB RAM, filtering time with MATLAB 5.2 running under Windows 98 is of the order of 50 ms for 60000 samples. This will be adequate for on-line electroencephalography (EEG) applications. The simplicity of the algorithm to calculate filter coefficients for an arbitrary cut-off frequency can be useful to modern EEG laboratories and software designers for electrophysiological applications.

Ictal oroalimentary automatisms with preserved consciousness: implications for the pathophysiology of automatisms and relevance to the international classification of seizures

A patient showing seizures presenting ictal automatisms with preserved consciousness is reported. A 30-year-old, right-handed man with normal development and without family history of epilepsy was referred for surgical treatment of epilepsy. At 15 he began to have seizures, starting with an epigastric aura, occasionally developing automatisms (lip-smacking, chewing), sometimes followed by tonic-clonic convulsions. At the time of referral, he averaged six convulsive seizures per year and one nonconvulsive per week. His sleep EEG showed sharpened slow activity over the right anterior quadrant magnetic resonance imaging (MRI) showed a benign lesion in the mesial aspect of the right occipital lobe. Simultaneous video monitoring and intracranial EEG with subdural strips recording from the right temporal and occipital lobes was undertaken. During one seizure, he had pronounced oroalimentary automatisms while holding a conversation with a technician, answering her questions, and explaining details of his seizures. Memory of this event was preserved. At seizure onset, spike activity was seen at the mesial occipital strips. At midseizure, high-voltage sharpened delta was seen throughout the right hemisphere. Left-sided scalp electrodes remained relatively uninvolved. The lesion, a dysembryoplastic neuroepithelial tumour was removed. Surgery was followed by abolition of seizures described. Because it is agreed that complex partial seizures require impaired consciousness, a history of automatisms with retained consciousness usually suggests nonepileptic attacks. This case suggests that automatisms in epileptic seizures can take place with minimal loss of consciousness, particularly if there is widespread but unilateral involvement. The need for a revision of the International Classification is suggested.

Interictal regional slow activity in temporal lobe epilepsy correlates with lateral temporal hypometabolism as imaged with 18FDG PET: neurophysiological and metabolic implications

OBJECTIVES

The phenomenon of interictal regional slow activity (IRSA) in temporal lobe epilepsy and its relation with cerebral glucose metabolism, clinical data, MRI, and histopathological findings was studied.

METHODS

Interictal 18F-fluorodeoxyglucose positron emission tomography (FDG PET) was performed under continuous scalp EEG monitoring in 28 patients with temporal lobe epilepsy not associated with intracranial foreign tissue lesions, all of whom subsequently underwent resective surgery. Regions of interest (ROIs) were drawn according to a standard template. IRSA was considered lateralised when showing a 4:1 or greater ratio of predominance on one side.

RESULTS

Sixteen patients (57%) had lateralised IRSA which was always ipsilateral to the resection and of maximal amplitude over the temporal areas. Its presence was significantly related to the presence of hypometabolism in the lateral temporal neocortex (p=0.0009). Logistic regression of the asymmetry indices for all measured cerebral regions confirmed a strong association between IRSA and decreased metabolism of the posterior lateral temporal neocortex only (p=0.009). No significant relation could be shown between slow activity and age at onset, duration of the epilepsy, seizure frequency, and MRI evidence for hippocampal atrophy. Furthermore, IRSA was not specifically related to mesial temporal sclerosis or any other pathology.

CONCLUSIONS

Interictal regional slowing in patients with temporal lobe epilepsy not associated with a mass lesion is topographically related to the epileptogenic area and therefore has a reliable lateralising, and possibly localising, value. Its presence is irrelevant to the severity or chronicity of the epilepsy as well as to lateral deactivation secondary to neuronal loss in the mesial temporal structures. Although slow EEG activity is generally considered as a non-specific sign of functional disturbance, interictal regional slowing in temporal lobe epilepsy should be conceptualised as a distinct electrographic phenomenon which is directly related to the epileptogenic abnormality. The strong correlation between interictal regional slowing and lateral temporal hypometabolism suggests in turn that the second may delineate a field of reduced neuronal inhibition which can receive interictal and ictal propagation.

Predictive value of interictal epileptiform discharges during non-REM sleep on scalp EEG recordings for the lateralization of epileptogenesis

PURPOSE

EEG recording during sleep is widely used in the assessment of epilepsy, particularly in candidates for surgery, yet the diagnostic value of this procedure is not well established. We evaluated the predictive reliability of interictal epileptiform discharges (IEDs) for localization in presurgical patients with temporal lobe epilepsy (TLE) during non-REM sleep.

METHODS

Preoperative scalp EEG recordings with waking and sleep states were assessed in 83 patients with TLE in whom localization of the epileptogenic zone was subsequently confirmed by successful surgical treatment (patient seizure-free >1 year).

RESULTS

The accuracy of EEG recordings for prediction of lateralization significantly changed from 51.8% during waking to 78.3% during sleep. After exclusion of patients who showed no discharges, the predictive value changed from 74.1 to 86.7%. However, in patients in whom the waking scalp EEG lateralized incorrectly, no improvement in reliability was achieved by sleep recording.

CONCLUSIONS

Our results suggest that IEDs occurring in non-REM sleep provide more accurate information for lateralization of epileptogenesis than do those occurring during waking. This gain of diagnostic information was obtained in patients who showed either bilateral or no discharges in waking records, because unilateral discharges arising de novo in sleep were always correctly lateralizing. On the other hand, in patients who showed unilateral discharges in the awake state, whether ipsilateral or contralateral to the epileptogenic zone, the findings were generally unchanged during sleep.

Origin and propagation of interictal discharges in the acute electrocorticogram. Implications for pathophysiology and surgical treatment of temporal lobe epilepsy

Although acute electrocorticography (ECoG) is routinely performed during epilepsy surgery there is little evidence that the extent of the discharging regions is a useful guide to tailoring the resection or that the findings are predictive of outcome or pathology. Patterns of discharge propagation have, however, rarely been considered in assessing the ECoG. We hypothesize that regions where discharges show earliest peaks ('leading regions') are located in the epileptogenic zone, whereas sites in which late, secondary, propagated activity occurs have less epileptogenic potential and do not need to be excised. To allow intraoperative topographic ECoG analysis, a computer program has been developed to identify leading regions and the sites showing greatest rates or amplitudes of spikes. Their topography has been compared retrospectively with pathology and seizure control in 42 consecutive patients following temporal lobe surgery. Leading regions were most often found in the hippocampus, the subtemporal cortex and the superior temporal gyrus. The most common propagation patterns were from hippocampus to subtemporal cortex and vice versa. There was no association between seizure outcome and the location of regions with greatest incidence or amplitude of spikes or location of leading regions. There was, however, a strong and significant association between poor outcome and non-removal of leading regions other than those in the posterior subtemporal cortex. All leading regions (other than posterior subtemporal) were resected in 27 patients of whom 25 had a favourable outcome. Leading regions (other than posterior subtemporal) remained in 14 patients of whom only four had a good outcome. One patient had no epileptiform activity in the ECoG and good outcome. Persistent posterior subtemporal leading regions remained in nine subjects; all had favourable outcome (Grades I or II) but only three were seizure free. These results suggest that: (i) interictal epileptiform discharges may originate from a complex interaction between separate regions, resulting in propagation and recruitment of neuronal activity along specific neural pathways; (ii) removal of all discharging areas appears unnecessary to achieve seizure control provided that leading regions (other than posterior subtemporal) are removed; and (iii) identification of such leading regions could be used to tailor resections in order to improve seizure control and reduce neurological, neuropsychological and psychiatric post-surgical morbidity.

The Maudsley Family Study, II: Endogenous event-related potentials in familial schizophrenia

Auditory event-related potentials (ERPs) were obtained from 33 schizophrenics, from 16 families multiply affected with schizophrenia, 57 of their non-schizophrenic first-degree relatives and 32 unrelated healthy controls. Transmission of schizophrenia in these families appeared unilinear with one parent only transmitting the disorder. Consequently, we were able to identify 10 presumed obligate carriers and study eight of them. Schizophrenic patients showed latency prolongation and amplitude reduction of the N100, N200 and P300 waves compared to controls. Their relatives showed similar abnormalities compared to controls. There was a trend for bimodal distribution of the P300 latency in the relatives, with 20 (35%) of them falling outside two standard deviations of the mean of the controls. These included six of the eight obligate carriers. Our results suggest that ERP abnormalities may serve as markers of genetic vulnerability in schizophrenia and may be useful in genetic linkage studies.

Power spectrum and intracranial EEG patterns at seizure onset in partial epilepsy

Intracranial electroencephalographic patterns of seizure onset during preoperative assessment with intracerebral and subdural electrodes have been correlated with surgical outcome in 15 patients with partial epilepsy assessed for surgery. The presence and topography of electrodecremental events, high frequency activity, irregular sharp waves intermixed with slow activity, spike-wave activity and rhythmic ictal transformation at seizure onset were studied in a total of 78 complex partial seizures. Raw traces from intracerebral and subdural recordings were assessed visually in conjunction with changes in the following spectral variables (calculated for consecutive 1.28 sec epochs): amplitude (sum of amplitude of all components within a frequency band), activity, mobility, and complexity. The time course of these variables during preictal and ictal periods was displayed and assessed. This technique proved effective for detecting low-amplitude high-frequency activity and subtle electrodecremental events. It was concluded that: (a) most patients (12/15) showed early electrodecremental events, generalised or local, mainly involving frequencies below 40 Hz; (b) generalised electrodecremental events at onset did not imply poor outcome; (c) localised high-frequency activity, between 20 and 80 Hz, was associated with a good outcome.

Fractal analysis of electroencephalographic signals intracerebrally recorded during 35 epileptic seizures: evaluation of a new method for synoptic visualisation of ictal events

Traditional electroencephalography (EEG) produces a large volume display of brain electrical activity, which creates problems particularly in assessment of long periods of intracranial, stereoelectroencephalographic (SEEG) recording. A method for fractal analysis that describes 100 SEEG data points in terms of a single estimate of fractal dimension (1 < FD < 2) is reported; the central processing unit time costs amount to approximately 2 min/Mbyte of input signal (using a Sun SPARCstation LX). The diagnostic sensitivity of this method, applied to quantification and synoptic visualisation of SEEG signals recorded during 35 epileptic seizures in 7 patients, is evaluated. It is found that the method consistently defines ictal onset in terms of rapid relative increase in FD across several channels. Clinically severe seizures are characterised by more intense and generalised ictal changes in FD than clinically less severe events. For all 7 patients, and for 75% of individual seizures, "fractal diagnoses" of anatomically defined ictal onset zone coincided closely with ictal onset zone independently determined by inspection of traditional EEG displays of the same data. We conclude that the method is a computationally feasible way to achieve substantial reduction in the volume of SEEG data without undue loss of diagnostically important information in the primary signal.

Intracerebral propagation of interictal activity in partial epilepsy: implications for source localisation

The hypothesis that focal scalp EEG and MEG interictal epileptiform activity can be modelled by single dipoles or by a limited number of dipoles was examined. The time course and spatial distribution of interictal activity recorded simultaneously by surface electrodes and by electrodes next to mesial temporal structures in 12 patients being assessed for epilepsy surgery have been studied to estimate the degree of confinement of neural activity present during interictal paroxysms, and the degree to which volume conduction and neural propagation take part in the diffusion of interictal activity. Also, intrapatient topographical correlations of ictal onset zone and deep interictal activity have been studied. Correlations between the amplitudes of deep and surface recordings, together with previous reports on the amplitude of scalp signals produced by artificially implanted dipoles suggest that the ratio of deep to surface activity recorded during interictal epileptiform activity on the scalp is around 1:2000. This implies that most such activity recorded on the scalp does not arise from volume conduction from deep structures but is generated in the underlying neocortex. Also, time delays of up to 220 ms recorded between interictal paroxysms at different recording sites show that interictal epileptiform activity can propagate neuronally within several milliseconds to relatively remote cortex. Large areas of archicortex and neocortex can then be simultaneously or sequentially active via three possible mechanisms: (1) by fast association fibres directly, (2) by fast association fibres that trigger local phenomena which in turn give rise to sharp/slow waves or spikes, and (3) propagation along the neocortex. The low ratio of deep-to-surface signal on the scalp and the simultaneous activation of large neocortical areas can yield spurious equivalent dipoles localised in deeper structures. Frequent interictal spike activities can also take place independently in areas other than the ictal onset zone and their interictal propagation to the surface is independent of their capacity to trigger seizures. It is concluded that: (1) the deep-to-surface ratios of electromagnetic fields from deep sources are extremely low on the scalp; (2) single dipoles or a limited number of dipoles are not adequate for surgical assessment; (3) the correct localisation of the onset of interictal activity does not necessarily imply the onset of seizures in the region or in the same hemisphere. It is suggested that, until volume conduction and neurophysiological propagation can be distinguished, semiempirical correlations between symptomatology, surgical outcome, and detailed presurgical modeling of the neocortical projection patterns by combined MEG, EEG, and MRI could be more fruitful than source localization with unrealistic source models.

MEG and EEG in epilepsy: is there a difference?

Interictal epileptiform activity recorded by scalp EEG, foramen ovale electrodes and MEG is discussed. Gross differences in waveform between the electric and magnetic records are discussed in the light of intracranial depth recordings.

A new technique for fractal analysis applied to human, intracerebrally recorded, ictal electroencephalographic signals

Application of a new method of fractal analysis to human, intracerebrally recorded, ictal electroencephalographic (EEG) signals is reported. 'Frameshift-Richardson' (FR) analysis involves estimation of fractal dimension (1 < FD < 2) of consecutive, overlapping 10-s epochs of digitised EEG data; it is suggested that this technique offers significant operational advantages over use of algorithms for FD estimation requiring preliminary reconstruction of EEG data in phase space. FR analysis was found to reduce substantially the volume of EEG data, without loss of diagnostically important information concerning onset, propagation and evolution of ictal EEG discharges. Arrhythmic EEG events were correlated with relatively increased FD; rhythmic EEG events with relatively decreased FD. It is proposed that development of this method may lead to: (i) enhanced definition and localisation of initial ictal changes in the EEG presumed due to multi-unit activity; and (ii) synoptic visualisation of long periods of EEG data.

An ASSEMBLER routine for on-line graphic display and averaging of data acquired on a personal microcomputer

An ASSEMBLER routine is described for data acquisition and "on-line" averaging, artefact rejection and graphic display of data on a personal microcomputer (IBM compatible). The user determines the number of input channels, sampling frequency, number of samples, input range, stimulation frequency (epoch frequency) and the number of epochs to be acquired and averaged. Data from each epoch are scanned in search of saturating artefacts and will be added to previous epochs if none is found. Data are then graphically displayed as voltage versus time before acquiring next epoch. Display options can be defined by the user at run time by means of the keyboard and include: display of last epoch, display of the average, storage screen and refreshing screen after every epoch. High data transfer rates and program speed allows for high stimulation rates in the presence of on line graphic display. The computer then behaves as a multichannel digital oscilloscope with access to large memory buffers, disk storage, high averaging capabilities, artefact rejection and wide potential for data analysis. Its applications to the recording of magnetic and electric evoked responses are illustrated. The program is available from the authors.

The effects of electrical stimulation of A and C visceral afferent fibres on the excitability of viscerosomatic neurones in the thoracic spinal cord of the cat

Single unit electrical activity has been recorded from viscerosomatic neurons in the lower thoracic spinal cord of decerebrate spinalized cats. The responses of the cells to electrical stimulation of afferent fibres in the splanchnic (SPLN) nerve and the effects of repetitive stimulation of somatic and visceral afferent C-fibres have been studied. Four groups of viscerosomatic neurones could be distinguished according to the type of visceral afferent input of the cells: (1) A-only cells (32.9%), driven only by stimulation of A delta afferent fibres in the SPLN nerve; (2) C-only cells (3%), driven only by stimulation of C afferent fibres in the SPLN nerve; (3) A + C cells (45.7%), driven by both A delta and C afferent fibres in the SPLN nerve; and (4) A + C? cells (18.6%), driven by A delta visceral afferents and showing signs of responsiveness to C-fibres though lacking a distinct response volley to visceral C-fibre activation. Two cells of the A + C group and located in lamina I of the dorsal horn responded to SPLN nerve stimulation in a manner consistent with the afferent fibre composition of the nerve, that is, showed evidence of strong monosynaptic links with SPLN afferent C-fibres and weaker responses to SPLN A delta afferents. Excitability changes of viscerosomatic neurones ('wind up', 'wind down' and changes in background activity) were also observed in the majority of neurones following electrical stimulation of somatic and of visceral afferent C-fibres.(ABSTRACT TRUNCATED AT 250 WORDS)

A fast data acquisition system for neurophysiological signals based on a personal microcomputer

A general purpose analog-to-digital conversion system and its interface for a low-cost personal computer (Commodore 64) are described. Special emphasis has been put on achieving a high sampling frequency rate (up to 20,000 samples/s) and a high discrimination (12 bits). It has likewise been attempted to increase the number of input channels (up to 8, by means of a multiplexer) and averaging capability since such features may be useful in a great number of neurobiological studies. Commercially available hardware elements have been employed and software has been developed in BASIC and 6510 Machine Code.