José Géraldo Ribeiro Vaz

Surgical clipping may lead to better results than coil embolization: results from a series of 101 consecutive unruptured intracranial aneurysms.

OBJECTIVERecent reports in the literature have described a significant discrepancy in adverse outcomes between coil embolization (CE; 10%) and surgical clipping (SC; 25%) for the management of unruptured intracranial aneurysms (UIA). This discrepancy led us to analyze our experience. METHODSIn 1996, we designed a prospective study of patients with UIA in which CE was considered the treatment of choice and was performed if the interventional neuroradiologists deemed the aneurysm’s fundus-to-neck ratio accessible for CE. SC was performed only if complete CE was unlikely to be achieved or in patients in whom CE already had failed. RESULTSCE was performed in 38 patients with at least one UIA (41 UIAs, 83% in the anterior circulation). SC was performed in 39 patients with at least one UIA unsuitable for CE (59 UIAs, including 6 after failed CE, 96.5% in the anterior circulation). For CE, the total obliteration rate was 56.1%, the subtotal was 14.6%, and CE failed in 29.3%. There were transient complications in 10% of the cases and permanent complications in 7.5%. Of the 12 failed CE procedures, 7 (58%) were performed for middle cerebral artery aneurysms. For SC, the total obliteration rate was 93.2%, the subtotal was 1.7%, and SC failed (wrapping) in 5.1%. There were transient complications in 16.3% of the patients and permanent complications in 1.7%. The success rate for CE was similar to that for SC only when CE was used for aneurysms with a fundus-to-neck ratio of at least 2.5. CONCLUSIONSC can produce better results than CE in patients with UIA of the anterior circulation. CE as a first-line treatment should be reserved for patients with UIAs with a fundus-to-neck ratio of 2.5 or greater.

Intraoperative magnetic resonance imaging at 3-T using a dual independent operating room-magnetic resonance imaging suite: development, feasibility, safety, and preliminary experience.

OBJECTIVEA twin neurosurgical magnetic resonance imaging (MRI) suite with 3-T intraoperative MRI (iMRI) was developed to be available to neurosurgeons for iMRI and for independent use by radiologists. METHODSThe suite was designed with one area dedicated to neurosurgery and the other to performing MRI under surgical conditions (sterility and anesthesia). The operating table is motorized, enabling transfer of the patient into the MRI system. These two areas can function independently, allowing the MRI area to be used for nonsurgical cases. We report the findings from the first 21 patients to undergo scheduled neurosurgery with iMRI in this suite (average age, 51 ± 24 yr; intracranial tumor, 18 patients; epilepsy surgery, 3 patients). RESULTSTwenty-six iMRI examinations were performed, 3 immediately before surgical incision, 9 during surgery (operative field partially closed), and 14 immediately postsurgery (operative field fully closed but patient still anesthetized and draped). Minor technical dysfunctions prolonged 10 iMRI procedures; however, no serious iMRI-related incidents occurred. Twenty-three iMRI examinations took an average of 78 ± 20 minutes to perform. In three patients, iMRI led to further tumor resection because removable residual tumor was identified. Complete tumor resection was achieved in 15 of the 18 cases. CONCLUSIONThe layout of the new complex allows open access to the 3-T iMRI system except when it is in use under surgical conditions. Three patients benefited from the iMRI examination to achieve total resection. No permanent complications were observed. Therefore, the 3-T iMRI is feasible and appears to be a safe tool for intraoperative surgical planning and assessment.

Patients with refractory epilepsy treated using a modified multiple subpial transection technique

BACKGROUND : Multiple subpial transection (MST) is a potential surgical treatment for patients with epileptogenic foci located in cortical areas with higher functions. As neurosurgical teams have become more experienced with MST, the original technique has adapted. OBJECTIVE : To report our 6-year experience with a modified MST technique. METHODS : The population included 62 consecutive patients with medically refractory epilepsy treated by MST, with a follow-up period ranging from 2 to 9 years. MST was performed on gyri under neuronavigation and guided by intraoperative electrocorticography. We performed radiating MST from a single cortical entry point. The MST technique was described according to the number of transections performed and the Brodmann areas (BAs) involved. Any MST-related complications were registered and followed up. Clinical outcome was described in terms of seizure suppression or reduction according to the Engel modified classification. RESULTS : Twelve patients underwent MST alone (MSTa), and 50 had MST with another procedure. The main MST sites were BA 4 (61%) and 3, 1, 2 (58%); in 22% of cases, MST was performed in BA 44, 22, 39, and 40. Permanent neurological deficits were observed in 4 (6.4%) patients; 2 minor deficits were MST related (3.2%). A reduction in the seizure rate of at least 50% was seen in 79% of patients (MSTa group, 75%), and 42% became seizure free (MSTa group, 33%). CONCLUSION : This study demonstrates the efficacy and low morbidity of radiating MST performed under neuronavigation and intraoperative electrocorticography. ABBREVIATIONS : BA, Brodmann areaEEG, electroencephalogramFDG, 18-fluorodeoxyglucoseioECoG, intraoperative electrocorticographyMRE, medically refractory epilepsyMST, multiple subpial transectionMSTa, multiple subpial transection aloneMST+, multiple subpial transection with other procedures.

Nociceptive Local Field Potentials Recorded from the Human Insula Are Not Specific for Nociception

The insula, particularly its posterior portion, is often regarded as a primary cortex for pain. However, this interpretation is largely based on reverse inference, and a specific involvement of the insula in pain has never been demonstrated. Taking advantage of the high spatiotemporal resolution of direct intracerebral recordings, we investigated whether the human insula exhibits local field potentials (LFPs) specific for pain. Forty-seven insular sites were investigated. Participants received brief stimuli belonging to four different modalities (nociceptive, vibrotactile, auditory, and visual). Both nociceptive stimuli and non-nociceptive vibrotactile, auditory, and visual stimuli elicited consistent LFPs in the posterior and anterior insula, with matching spatial distributions. Furthermore, a blind source separation procedure showed that nociceptive LFPs are largely explained by multimodal neural activity also contributing to non-nociceptive LFPs. By revealing that LFPs elicited by nociceptive stimuli reflect activity unrelated to nociception and pain, our results confute the widespread assumption that these brain responses are a signature for pain perception and its modulation.

Gamma-band oscillations preferential for nociception can be recorded in the human insula

Abstract Transient nociceptive stimuli elicit robust phase‐locked local field potentials (LFPs) in the human insula. However, these responses are not preferential for nociception, as they are also elicited by transient non‐nociceptive vibrotactile, auditory, and visual stimuli. Here, we investigated whether another feature of insular activity, namely gamma‐band oscillations (GBOs), is preferentially observed in response to nociceptive stimuli. Although nociception‐evoked GBOs have never been explored in the insula, previous scalp electroencephalography and magnetoencephalography studies suggest that nociceptive stimuli elicit GBOs in other areas such as the primary somatosensory and prefrontal cortices, and that this activity could be closely related to pain perception. Furthermore, tracing studies showed that the insula is a primary target of spinothalamic input. Using depth electrodes implanted in 9 patients investigated for epilepsy, we acquired insular responses to brief thermonociceptive stimuli and similarly arousing non‐nociceptive vibrotactile, auditory, and visual stimuli (59 insular sites). As compared with non‐nociceptive stimuli, nociceptive stimuli elicited a markedly stronger enhancement of GBOs (150‐300 ms poststimulus) at all insular sites, suggesting that this feature of insular activity is preferential for thermonociception. Although this activity was also present in temporal and frontal regions, its magnitude was significantly greater in the insula as compared with these other regions.

Syndrome of the trephined, a case report.

Syndrome of the trephined also called ‘‘sinking skin flap syndrome’’ is a rare and late complication of the craniectomy. It appears in the weeks or months (3 months in average) after the surgery and is characterized by a neurological deterioration, not explained by other etiologies. This syndrome also associates various symptoms such as headaches, motor impairments, cognitive disorders, alertness disorders and also in some cases autonomic dysfunction. This clinical picture can be aggravated by orthostatism and dehydration. A characteristic neurological improvement of the patient’s neurological state after having replaced the skull bone flap will validate the diagnosis [1–5].

Post-resection electrocorticography has no added value in epilepsy surgery.

Intra-operative electrocorticography (ECoG) has been traditionally used in the surgical management of medically refractory partial epilepsies to identify the limits of the epileptogenic zone. This retrospective study had as goal to evaluate whether tailored surgery based on the presurgical evaluation completed by intra-operative post-resection ECoG improves outcome. We reviewed 94 cases of epilepsy surgery with intra-operative ECoG and determined how many had an ECoG-guided surgical procedure in addition to the initial planned surgery. We also reviewed the presence of specific recurrent ECoG patterns of interictal epileptiform discharges (IED) in the exposed cortical surface, such as: electrographic seizures, bursts, intermittent spike waves, polyspikes or fast rhythms and continuous or quasi-continuous spiking. When performing a post-resection ECoG-tailored surgery, outcome did not improve in lesional or non-lesional epilepsy. Postoperative residual IED did not correlate with a poorer outcome. In our study, the persistence of post-resection IED on ECoG is not correlated with outcome in patients with lesional or non-lesional epilepsy.

Syndrome of the trephined revealed by vertical diplopia

A 29 year-old man underwent a bi-frontal decompressive craniectomy to drain a life-threatening post-traumatic intraparenchymal hematoma. The bone flap became infected and had to be removed 13 months after the initial surgery. Seven months later, the patient complained of vertical diplopia which was more prominent in the evening and disappeared upon awakening, suggesting posture-related occurrence of symptoms. Ophthalmologic examination revealed a limitation of the upward gaze of the left eye with upbeat nystagmus, and a bilateral horizontal gaze evoked nystagmus associated with irregular dysmetric saccades. Ophthalmological examination suggested a midbrain dysfunction. MRI revealed an impingement of the mesencephalon by brain shift after craniectomy suggesting syndrome of the trephined (ST)/sinking skin flap syndrome. Cranioplasty was performed, and symptoms disappeared shortly after. A follow-up MRI 2 months later showed a normalized shape of the previously impinged mesencephalon. ST is a complication observed in 12–26 % of patients having undergone craniectomy and is featured by neurological deterioration after the removal of a large skull bone flap [1, 2]. Frequently reported symptoms are posture-related chronic arrest of rehabilitation or acute deterioration, dizziness, mental depression, sensorimotor or autonomic deficits, and cognitive impairments [3, 4]. Diplopia has been rarely described and may be the consequence of the stretching of an oculomotor nerve or, whenever clinical presentation is more complex, a midbrain lesion. The most common radiological signs are a sunken skin flap, a