How to decrease the impact of surgical scar in the correction of sagittal synostosis

INTRODUCTION. Sagittal synostosis can be surgically corrected by a variety of surgical procedures, all of them, however, burdened by a significant cosmetic impact owing to the visibility of the surgical scar. TECHNICAL NOTE. In this note, the author describes a surgical procedure that utilizes six strategically placed short scalp incisions instead of the traditional S-shaped or biparietal scalp incisions. Though still allowing effective correction of the malformative condition, the new procedure has only a minor cosmetic impact and leads to easier intraoperative and postoperative management of the patient. The procedure can be carried out using both standard or endoscopic techniques.     

皮肤软组织扩张修复头面部外伤性缺损的早期应用

目的：常规应用植皮或单纯的皮瓣修复头面部皮肤软组织缺损从美学角度讲存在一定的缺点。总结皮肤软组织扩张器在头面部外伤性缺损早期修复中的应用情况。 方法：①对象：选择2005-09/2007-10在解放军第四军医大学西京医院整形外科住院的部分外伤性头面部皮肤软组织缺损患者15例。其中男12例，女3例；年龄5~51岁。面部缺损4例，头皮缺损7例，面部并头皮缺损4例，缺损面积3 cm×5 cm~ 7 cm×11 cm。②方法：积极改善患者全身情况，加强局部创面处理，待全身情况稳定、创面肉芽组织新鲜的情况下，行清创、刃厚植皮术，覆盖除骨外露以外所有创面。同时或延期于缺损周围正常组织下埋置一至数枚容量不等（80~450 mL）的扩张器。皮片成活并稳定后，开始扩张器注水，约两三个月注水完成后行扩张器二期术，切除骨外露周围不稳定的瘢痕组织（包括早期植皮部分），用设计的扩张皮瓣覆盖缺损，完成修复。 结果：1例头皮扩张器在扩张后期出现了外露，及时进行二期手术修复缺损。所有患者头面部皮肤软组织缺损在短期内均得到了有效修复，2例患者在二期术后出现了轻度的器官移位，术后半年症状消失，所有病例无瘢痕性秃发发生。 结论：皮肤扩张可用于头面部外伤性缺损的早期修复，合理的选择、正确的应用可以获得满意的效果。     

Mini-invasive surgical technique for sagittal craniosynostosis

Introduction

Several techniques are currently available for the surgical correction of sagittal craniosynostosis. The most recently introduced ones have been specifically designed to perform a mini-invasive approach in order to reduce the postoperative morbidity. Herein, the surgical steps of a personal, mini-invasive technique used to decrease the impact of the surgical scar are described.

Surgical technique

The traditional biparietal skull expansion is realized through two to six short skin linear incisions (2–3?cm long) strategically scattered over the scalp, which allow the surgeon to perform a wide sagittal synostectomy, linear craniectomies along the coronal and lambdoid sutures, and barrel stave osteotomies on the frontal and occipital bones, if needed. No special instruments or postoperative molding therapy is required.

Discussion

The main advantages of this technique are the poor visibility of the surgical scar, the reduction of the perioperative morbidity (blood transfusion, orbital edema, subcutaneous fluid collection), and the shortening of surgical times and postoperative hospitalization. The main limits are represented by the minor correction of the frontal bossing and the old age of children at surgery (no optimal results after 10–12?months of age).     

Effectiveness of a limited invasive scalp approach in the correction of sagittal craniosynostosis

Background Several surgical techniques have been proposed for the correction of sagittal craniosynostosis. Extensive procedures seem to ensure the most stable long-term results and are more indicated in the older age group. Mini-invasive approaches are particularly useful in the very young infant as they are associated with a minor surgical risk. Furthermore, they are weighted by a minor cosmetic impact related to a less extended surgical scar. Materials and methods Data of the last 94 consecutively operated on scaphocephalic patients have been reviewed to verify the effectiveness of a personal limited-invasive approach based on four to six short linear scalp incisions vs the traditional bicoronal skin flap. The patients have been divided in two groups: (1) the control group (2000–2002): 45 children, operated on by means of a traditional bicoronal skin incision, and (2) the study group (2002–2004): 49 children, treated through four to six linear scalp incisions. The patients’ variables were comparable. The results were evaluated in terms of duration of the surgical procedure, estimated blood loss (EBL), transfusion risk, postoperative complication rate, length of hospital stay, and postoperative cephalic index and cosmetic outcome as perceived by the patients’ families. Results No significant differences between the two groups were found about the early and the long-term surgical results; however, about one third of the subjects of the control group complained about the visibility of the surgical scar. In the study group, a significant reduction in the duration of the operation (p < 0.0001), postoperative hospital stay (p < 0.0001), EBL (p = 0.011), transfusion risk (p = 0.018), and complication rate (p = 0.016) was observed. Conclusion The current trend in the management of scaphocephaly is to favor simplified surgical procedures to be performed in the younger ages prevalently. The technique here presented allows achieving a stable long-term cranial reshaping, even when performed in the very young patient. The technique can be utilized also in older subjects with results comparable to those of more extensive surgical procedures. This less invasive technique is weighted by minor complication rates and minor impact of the surgical scar. Presented at the Consensus Conference on Pediatric Neurosurgery, Rome, 1–2 December 2006.     

Multi-modality neurophysiological monitoring during surgery for adult tethered cord syndrome

During complex microneurosurgery performed in patients with tethered cord syndrome, the conus medullaris and the roots that innervate the lower limbs, bladder and bowel are potentially exposed to damage. The aim of multimodality intraoperative monitoring (IOM) is to reduce the risk of inadvertent injury of neural tissue. We simultaneously record tibial nerve somatosensory evoked potentials (SSEPs) from the scalp and free run electromyography (EMG) of limb muscles supplied by L2 to S2 roots, anal and urethral sphincters. We also identify critical neural structures in the operative field, including the conus and exiting nerve roots, with a nerve stimulator to evoke EMG. SSEPs assess the sensory pathways mainly mediated by the S1 roots. Continuous EMG provides the surgeon with immediate auditory feedback resulting from irritative discharges triggered by manipulation of nerve fibres. Microstimulation can distinguish the filum terminale, scar tissue and invasive tumors from functional neural tissue, thus minimizing the risk of iatrogenic injury. Overall multimodality IOM proves a valuable adjunct to microneurosurgery of the lumbosacral spine.     

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.     

Simultaneously recorded intracranial and scalp high frequency oscillations help identify patients with poor postsurgical seizure outcome

ObjectiveHigh frequency oscillations (HFO) between 80–500 Hz are markers of epileptic areas in intracranial and maybe also scalp EEG. We investigate simultaneous recordings of scalp and intracranial EEG and hypothesize that scalp HFOs provide important additional clinical information in the presurgical setting.MethodsSpikes and HFOs were visually identified in all intracranial scalp EEG channels. Analysis of correlation of event location between intracranial and scalp EEG as well as relationship between events and the SOZ and zone of surgical removal was performed.Results24 patients could be included, 23 showed spikes and 19 HFOs on scalp recordings. In 15/19 patients highest scalp HFO rate was located over the implantation side, with 13 patients having the highest scalp and intracranial HFO rate over the same region. 17 patients underwent surgery, 7 became seizure free. Patients with poor post-operative outcome showed significantly more regions with HFO than those with seizure free outcome.ConclusionsScalp HFOs are mostly located over the SOZ. Widespread scalp HFOs are indicative of a larger epileptic network and associated with poor postsurgical outcome.SignificanceAnalysis of scalp HFO add clinically important information about the extent of epileptic areas during presurgical simultaneous scalp and intracranial EEG recordings.     

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.     

Scalp arteriovenous malformations

AIMS: We discuss our experience with the surgical management of scalp vascular malformation and review the literature on the subject. SETTINGS AND DESIGN: A prospective case-control study of eight patients with scalp vascular malformations admitted to our hospital between 1997 and 2002. METHODS AND MATERIALS: All the patients were investigated with selective internal and external carotid angiography. Depending upon the origin of feeding arteries, the scalp vascular malformations were classified into two categories: Group I: the primary scalp arteriovenous malformations and Group II: secondary venous dilatations. Six patients belonged to Group I and two patients were in Group II. RESULTS: Five patients belonging to Group I underwent successful excision of the arteriovenous malformation. There was no recurrence in this group. Of the two patients in Group II, one patient who had scalp vascular dilatation simulating a primary scalp vascular malformation underwent excision of the lesion. This patient developed severe postoperative brain edema and died. CONCLUSIONS: Primary scalp vascular malformation can be excised safely. However, excision of secondary scalp venous dilatation without treatment of the intracranial component can be dangerous.     

Selective scalp block decreases short term post-operative pain scores and opioid use after craniotomy: A case series

There is no consensus on the management of post-craniotomy pain. Several randomized controlled trials have examined the use of a regional scalp block for post-craniotomy pain. We aim to investigate whether scalp block affected short or long-term pain levels and opioid use after craniotomy. This study prospectively administered selective scalp blocks (lesser occipital, preauricular nerve block + pin site block) in 20 consecutive patients undergoing craniotomy for semicircular canal dehiscence. Anesthesia, pain, and opioid outcomes in these patients were compared to 40 consecutive historic controls. There was no significant difference in patient demographics between the two groups and no complications related to selective scalp block. The time between the end of procedure and end of anesthesia decreased in the scalp block group (16 vs 21 min, P = 0.047). Pain scores were significantly less in the scalp block group for the first 4 h, after which there was no statistically significant difference. Time to opioid rescue was longer in the scalp block group (3.6 vs 1.8 h, HR 0.487, P = 0.0361) and opioid use in the first 7 h was significantly less in the scalp block group. Total opioid use, outpatient opioid use, and length of stay did not differ. Selective scalp block is a safe and effective tool for short-term management of postoperative pain after craniotomy and decreases the medication requirement during emergence and recovery. Selective scalp block can speed up OR turnover but is not efficacious in the treatment of postoperative pain beyond this point.     

Cortical contribution to scalp EEG gamma rhythms associated with epileptic spasms

The cortical contribution for the generation of gamma rhythms detected from scalp ictal EEG was studied in unique cases of epileptic spasms and a review of the related literature was conducted. Ictal scalp gamma rhythms were investigated through time–frequency analysis in two cases with a combination of focal seizures and spasms and another case with spasms associated with cortical dysplasia. In the two patients with combined seizures, the scalp distribution of ictal gamma rhythms was related to that of focal seizure activity. In the third patient, an asymmetric distribution of the ictal scalp gamma rhythms was transiently revealed in correspondence to the dysplasic cortex during hormonal treatment. Therefore, the dominant region of scalp gamma rhythms may correspond to the epileptogenic cortical area. The current findings have reinforced the possibility of the cortical generation of ictal scalp gamma rhythms associated with spasms. The detection of high frequencies through scalp EEG is a technical challenge, however, and the clinical significance of scalp gamma rhythms may not be the same as that of invasively recorded high frequencies. Further studies on the pathophysiological mechanisms related to the generation of spasms involving high frequencies are necessary in the future, and the development of animal models of spasms will play an important role in this regard.     

互动式头针治疗脑卒中恢复期患者步态的康复疗效评价

目的 :观察互动式头针对脑卒中恢复期患者偏瘫步态及移动能力的治疗作用。方法 :将连续纳入研究的90例符合病例选择标准的脑卒中恢复期伴偏瘫步态的患者随机分入互动式头针组(30例,头针治疗同时进行康复训练)、传统头针组(30例,头针治疗后进行康复训练)和对照组(30例,仅康复训练),连续治疗3个月。采用5 m折返行走试验评估治疗后的步态质量改善情况,采用改良Barthel指数评估移动能力改善对整体康复疗效的影响。结果 :治疗后,3组患者的5 m折返行走时间和改良Barthel指数均较治疗前显著改善(P值均0.01)。互动式头针组治疗前后5 m折返行走时间的差值显著大于传统头针组(P0.05)和对照组(P0.01);治疗前后改良Barthel指数的差值显著大于对照组(P0.05),亦高于传统头针组,但差异无统计学意义(P0.05)。结论 :互动式头针治疗有助于脑卒中恢复期患者偏瘫步态的改善,从而提高其移动能力。     

Localizing value of scalp EEG spikes: a simultaneous scalp and intracranial study.

OBJECTIVE: To determine the relationship between cortical origins of interictal and ictal EEG discharges in patients with temporal lobe epilepsy. METHODS: Simultaneous cortical and scalp EEG recordings were obtained from six patients with temporal lobe epilepsy. Subdural electrode contacts active at seizure onset and when scalp ictal rhythms became evident were identified. Similarly, cortical substrates of scalp EEG spikes were identified at spike peak and at the initial rising phase of the potential. RESULTS: Intracranial seizure onsets were commonly focal and involved only a few electrode contacts, as opposed to scalp ictal rhythms, which required synchronous activation of multiple electrode contacts. At the peak of scalp spikes, multiple electrode contacts were similarly active. However, at spike onset, cortical substrates were more discrete and commonly involved electrodes similar to that of seizure onsets. CONCLUSIONS: Scalp EEG ictal rhythms and the peak of a scalp spike may poorly localize the epileptogenic focus because of propagation. Cortical source area at scalp spike onset is more discrete, however, and the seizure onset zone often lies within this area. SIGNIFICANCE: Analysis of scalp spikes, such as source modeling, at their initial rising phase might provide useful localizing information about seizure origins in the same patient.     

Characteristics of scalp electrical fields associated with deep medial temporal epileptiform discharges.

OBJECTIVE: To determine scalp characteristics of epileptiform discharges arising from medial temporal structures (MT). METHODS: Signal-to-noise ratio was increased by averaging simultaneous recordings from intracranial and scalp electrodes synchronised on discharges recorded by foramen ovale (FO) electrodes. The topography, amplitude and distribution of averaged scalp signals were analysed. RESULTS: Four thousand three hundred and twenty-seven discharges from 20 patients were averaged into 77 patterns. Before averaging, only 9% of discharges were detectable on the scalp without the need of simultaneous FO recordings (SED). A further 72.3% of discharges fell into averaged patterns that could be detected on the scalp as small transients before or after averaging (STBA or STAA). In 18.7% of discharges, no scalp signal was seen after averaging. Whereas most SED patterns had largest amplitude on the scalp at anterior temporal electrodes, STBA and STAA patterns showed greater variability and more widespread scalp fields, suggesting a deeper source. Dipole source localisation modelled the majority of SED patterns as radial dipoles located just behind the eye. In contrast, dipoles corresponding to STBA or STAA patterns showed greater variability in location and orientation and tended to be located at MT. CONCLUSIONS: SED patterns seem to arise from widespread subtemporal and/or superficial neocortical activation, generating EEG fields that are distorted by the high electrical conductivity of anterior cranial foramina. In contrast, STBA and STAA patterns represent electrical fields from neuronal activity more restricted to MT, that reach the scalp highly attenuated by volume-conduction and less distorted by cranial foramina. SIGNIFICANCE: Low amplitude scalp signals can be related to MT activity and must be taken into consideration for the diagnosis of temporal lobe epilepsy, pre-surgical assessment and for valid modelling of deep sources from the scalp EEG and magnetoencephalogram.     

Focal magnetoencephalographic spikes in the superior temporal plane undetected by scalp EEG.

Temporal lobe spikes were detected by magnetoencephalography (MEG), but not by standard scalp electroencephalography (EEG), in a patient with intractable complex partial seizures. Simultaneous recording of scalp EEG and MEG revealed 2 different types of spike discharges: sporadic single spikes detected by both EEG and MEG which were localised diffusely in the right temporal lobe; and rhythmic MEG spike discharges that were not detected by scalp EEG, focally localised in the posterior part of the superior temporal plane. The tangential current orientation to the scalp may explain the different sensitivity of scalp EEG and MEG to rhythmic discharges. This study shows the unique sensitivity of MEG to epileptic activity in the superior temporal plane.     

婴幼儿头皮血肿及合并症的处理

目的 探讨婴幼儿头皮血肿及合并症的处理.方法 2004年1月至2006年6月诊治99例婴幼儿头皮血肿及合并症,均经头颅CT扣描证实.头皮血肿白行吸收16例,穿刺44例,血肿机化硬块切除39例.结果 44例头皮血肿穿刺和39例机化硬块术后,无一例感染和再出血,并恢复正常头颅外形.颅内合并症经综合治疗后,恢复良好.结论 婴幼儿头皮血肿及合并症应早期诊断和治疗,效果佳.     

The impact of cerebral source area and synchrony on recording scalp electroencephalography ictal patterns

PURPOSE: To determine the cerebral electroencephalography (EEG) substrates of scalp EEG seizure patterns, such as source area and synchrony, and in so doing assess the limitations of scalp seizure recording in the localization of seizure onset zones in patients with temporal lobe epilepsy. METHODS: We recorded simultaneously 26 channels of scalp EEG with subtemporal supplementary electrodes and 46-98 channels of intracranial EEG in presurgical candidates with temporal lobe epilepsy. We correlated intracranial EEG source area and synchrony at seizure onset with the corresponding scalp EEG. Eighty-six simultaneous intracranial- and scalp-recorded seizures from 23 patients were evaluated. RESULTS: Thirty-four intracranial ictal discharges (40%) from 9 patients (39%) had sufficient cortical source area (namely > 10 cm(2)) and synchrony at seizure onset to produce a simultaneous or nearly simultaneous focal scalp EEG ictal pattern. Forty-one intracranial ictal discharges (48%) from 10 patients (43%) gradually achieved the necessary source area and synchrony over several seconds to generate a scalp EEG ictal pattern. These scalp rhythms were lateralized, but not localizable as to seizure origin. Eleven intracranial ictal discharges (13%) from 4 patients (17%) recruited the necessary source area, but lacked sufficient synchrony to result in a clearly localized or lateralized scalp ictal pattern. CONCLUSIONS: Sufficient source area and synchrony are mandatory cerebral EEG requirements for generating scalp-recordable ictal EEG patterns. The dynamic interaction of cortical source area and synchrony at the onset and during a seizure is a primary reason for heterogeneous scalp ictal EEG patterns.     

颞叶癫痫放电在颅内外传播模式的研究

目的探索颞叶癫痫放电在颅内外的传播方式。方法对无法通过无创手段定侧、定位而高度怀疑为难治性颞叶癫痫的病人行双颞钻孔颅内电极植入术,同步记录10-20头皮脑电和双侧蝶骨电极。对最终确诊的颞叶癫痫病人,分析其同步记录脑电图,测量颅内癫痫起源传播到颅内外各个电极点的时间间隔。研究发作期放电的颅内外传播方式。结果颞下、海马、颞极和颞叶外侧各部位起源的癫痫在颅内外传播有各自的方式：①颞下→对侧海马或颞下→同侧蝶骨→对侧蝶骨→同侧前或中颞头皮→对侧前或中颞头皮;②海马→同侧蝶骨→对侧海马或颞下→对侧蝶骨→同侧前或中颞头皮→对侧前或中颞头皮;③颞极→对侧海马或颞下→同侧蝶骨→同侧前或中颞头皮→对侧蝶骨→对侧前或中颞头皮;④颞叶外侧→同侧中颞头皮→同侧蝶骨→对侧前颞或颞下→对侧蝶骨→对侧前或中颞头皮。结论了解各部位颞叶癫痫放电的颅内外传播顺序有助于癫痫灶的定侧、定位。     

Fast periodic visual stimulation to highlight the relationship between human intracerebral recordings and scalp electroencephalography

Despite being of primary importance for fundamental research and clinical studies, the relationship between local neural population activity and scalp electroencephalography (EEG) in humans remains largely unknown. Here we report simultaneous scalp and intracerebral EEG responses to face stimuli in a unique epileptic patient implanted with 27 intracerebral recording contacts in the right occipitotemporal cortex. The patient was shown images of faces appearing at a frequency of 6 Hz, which elicits neural responses at this exact frequency. Response quantification at this frequency allowed to objectively relate the neural activity measured inside and outside the brain. The patient exhibited typical 6 Hz responses on the scalp at the right occipitotemporal sites. Moreover, there was a clear spatial correspondence between these scalp responses and intracerebral signals in the right lateral inferior occipital gyrus, both in amplitude and in phase. Nevertheless, the signal measured on the scalp and inside the brain at nearby locations showed a 10‐fold difference in amplitude due to electrical insulation from the head. To further quantify the relationship between the scalp and intracerebral recordings, we used an approach correlating time‐varying signals at the stimulation frequency across scalp and intracerebral channels. This analysis revealed a focused and right‐lateralized correspondence between the scalp and intracerebral recordings that were specific to the face stimulation is more broadly distributed in various control situations. These results demonstrate the interest of a frequency tagging approach in characterizing the electrical propagation from brain sources to scalp EEG sensors and in identifying the cortical sources of brain functions from these recordings.     

Intracranial EEG substrates of scalp EEG interictal spikes

PURPOSE: To determine the area of cortical generators of scalp EEG interictal spikes, such as those in the temporal lobe epilepsy. METHODS: We recorded simultaneously 26 channels of scalp EEG with subtemporal supplementary electrodes and 46 to 98 channels of intracranial EEG in 16 surgery candidates with temporal lobe epilepsy. Cerebral discharges with and without scalp EEG correlates were identified, and the area of cortical sources was estimated from the number of electrode contacts demonstrating concurrent depolarization. RESULTS: We reviewed approximately 600 interictal spikes recorded with intracranial EEG. Only a very few of these cortical spikes were associated with scalp recognizable potentials; 90% of cortical spikes with a source area of >10 cm(2) produced scalp EEG spikes, whereas only 10% of cortical spikes having <10 cm(2) of source area produced scalp potentials. Intracranial spikes with <6 cm(2) of area were never associated with scalp EEG spikes. CONCLUSIONS: Cerebral sources of scalp EEG spikes are larger than commonly thought. Synchronous or at least temporally overlapping activation of 10-20 cm(2) of gyral cortex is common. The attenuating property of the skull may actually serve a useful role in filtering out all but the most significant interictal discharges that can recruit substantial surrounding cortex.