Patterns of Failure After Linear Accelerator Radiosurgery for Cerebral Arteriovenous Malformations.

BACKGROUND: Numerous studies have assessed the predictive factors for the arteriovenous malformation (AVM) response to stereotactic radiosurgery (SRS). However, only a few have discussed the causes of failure. The aim of the present study was to evaluate the patterns of failure in patients with AVM who had undergone linear accelerator SRS. METHODS: We performed a retrospective analysis of 288 patients who had undergone linear accelerator SRS in our institution from 1995 to 2011. Failure was defined from the findings of the follow-up angiogram at 5 years, with failure identified in 44 patients. The distribution of causes was estimated using a descriptive analysis of literature-based causes, including a minimal margin dose of <18 Gy, a residual nidus outside the initial targeted volume, previous embolization, recanalization, and the size of the target volume. We also analyzed the associations among the causes. RESULTS: Incomplete nidus identification (41%) and previous embolization (77%) were the most frequently observed conditions in patients with failure. Patients who had undergone previous embolization, for whom the cause of failure had always been identified (P = 0.001), were younger (P = 0.004) and had had a larger nidus volume (P = 0.025). Recanalization was rare (5 of 34 patients) and had occurred exclusively in women (P = 0.048). Larger nidus volumes were less frequent (mean, 2.18 ± 2.2 cm3; range, 0.13-10.8 cm3) and had been observed mainly in women when >2 cm3 (P = 0.012). An insufficient dose was observed in 9 patients and had occurred in the case of a larger volume (P = 0.031), which had resulted in dosimetry constraints in 3 patients and treatment in the vicinity of eloquent zones in 6 patients. No known cause was found in 5 patients, 4 of whom had had a low Spetzler-Martin grade (I and II; P = 0.003), suggestive of radioresistance. CONCLUSION: The results of our detailed analysis have highlighted the distribution of the causes of failure and the potential role of radioresistance in treatment failure.

CT-scan contouring technique allows for direct and reliable measurements of the cochlear duct length: implication in cochlear implantation with straight electrode-arrays.

OBJECTIVES: The advent of hybrid electro-acoustic implants requires precise positioning of the electrode-array (EA) within the cochlea. The cochlea size, that is, the length of the cochlear scala tympani, is often indirectly estimated from distance A by Escudé's method. This technique has been confirmed by anatomical studies, in a bunch of cadaveric specimens, but it is not yet widely established in the field of computed tomography (CT). We compared cochlear duct length obtained by Escudé's method to those directly acquired on CT images. MATERIALS AND METHODS: The lengths of cochlear scala tympani were directly measured on CT scans by contouring the external cochlear wall (contouring technique-CoT). In fifteen patients implanted with a straight EA, the length of the EA and the measured length of the cochlea by the CoT were compared, to check the reliability of the CoT. Then, in 200 CT-scans, the length of the cochlear duct was measured by the CoT then compared to Escudé's method. RESULTS: In the 200 CT-scans which served for cochlear length measurements, a significant variability between the cochleae were observed, as expected. At 360°, the correlation between the measurements of the length of the cochlear scala tympani between the two techniques differed, with a difference of 0.2 ± 0.7 mm at 360° (extreme: 2 mm; p < 0.001) and 2.2 ± 1.2 mm at 540° (extreme: 5.6 mm; p < 0.001). CONCLUSION: The CoT can predict with accuracy the length of EA-insertion depth, more precisely than estimation methods such as Escudé's.

Deep brain stimulation in five patients with severe disorders of consciousness.

OBJECTIVE: The efficacy of deep brain stimulation in disorders of consciousness remains inconclusive. We investigated bilateral 30-Hz low-frequency stimulation designed to overdrive neuronal activity by dual pallido-thalamic targeting, using the Coma Recovery Scale Revised (CRS-R) to assess conscious behavior. METHODS: We conducted a prospective, single center, observational 11-month pilot study comprising four phases: baseline (2 months); surgery and titration (1 month); blind, random, crossover, 1.5-month ON and OFF periods; and unblinded, 5-month stimulation ON. Five adult patients were included: one unresponsive-wakefulness-syndrome male (traumatic brain injury); and four patients in a minimally conscious state, one male (traumatic brain injury) and three females (two hemorrhagic strokes and one traumatic brain injury). Primary outcome measures focused on CRS-R scores. Secondary outcome measures focused notably on baseline brain metabolism and variation in activity (stimulation ON - baseline) using normalized fluorodeoxyglucose positron emission tomography maps. Statistical analysis used random-effect models. RESULTS: The two male patients (one minimally conscious and one unresponsive wakefulness syndrome) showed improved mean CRS-R scores (stimulation ON vs. baseline), in auditory, visual and oromotor/verbal subscores, and visual subscores respectively. The metabolism of the medial cortices (low at baseline in all five patients) increased specifically in the two responders. INTERPRETATION: Our findings show there were robust but limited individual clinical benefits, mainly in visual and auditory processes. Overall modifications seem linked to the modulation of thalamo-cortico-basal and tegmental loops activating default mode network cortices. Specifically, in the two responders there was an increase in medial cortex activity related to internal awareness.

Subthalamus stimulation in Parkinson disease: Accounting for the bilaterality of contacts.

BACKGROUND: Deep brain stimulation (DBS) in Parkinson's disease uses bi-hemispheric high-frequency stimulation within the subthalamus, however, the specific impacts of bilaterality of DBS are still not clear. Thus, we aimed to study the individual-level clinical impact of locations of right-left contact pair-up accounting for each subthalamic nucleus (STN) anatomy. METHODS: Contact locations and effects at 1 year were studied retrospectively in an unselected series of 53 patients operated between 2004 and 2010. Location of contacts was defined relatively to the main axis of STN used to map longitudinal and transversal positions, and STN membership (out meaning out-of-STN). Contact pairings were described via three methods: (i) Unified contact location (UCL) collapsing DBS into an all-in-one contact; (ii) balance of contact pair-up (BCPU), defined as symmetric or asymmetric regardless of laterality; (iii) hemisphere-wise most frequent contact pair-up (MFCP) regardless of BCPU. Clinical data were: mean levodopa equivalent dose, Unified Parkinson's Disease Rating Scale (UPDRS) motor score III without medication, UPDRS II and III speech sub-scores, UPDRS II freezing sub-score, 1 year versus preoperative values, with and without levodopa. Ad-hoc two-sided tests were used for statistical analysis. RESULTS: Worsening speech, was more frequent for UCL_out patients and when the left MFCP contact was rear and/or superolateral, however, it less frequent for BCPU-asymmetric patients. Worsening freezing was more frequent when the right MFCP contact was rear and superolateral. CONCLUSIONS: These results point to strategies for minimizing dysarthria and freezing as adverse effects of DBS.

Validation of a noninvasive test routinely used in otology for the diagnosis of cerebrospinal fluid shunt malfunction in patients with normal pressure hydrocephalus.

OBJECTIVE: Ventriculoperitoneal shunting is the first-line treatment for normal pressure hydrocephalus. Noninvasive auditory tests based on recorded otoacoustic emissions were assessed, as currently used for universal neonatal hearing screenings, for the diagnosis of cerebrospinal fluid shunt malfunction. The test was designed based on previous works, which demonstrated that an intracranial pressure change induces a proportional, characteristic, otoacoustic-emission phase shift. METHODS: Forty-four patients with normal pressure hydrocephalus (23 idiopathic and 21 secondary cases) were included in this prospective observational study. The male:female sex ratio was 1.44, the age range was 21-87 years (mean age 64.3 years), and the range of the follow-up period was 1-3 years (mean 20 months). Patients were implanted with a Sophy SU8 adjustable-pressure valve as the ventriculoperitoneal shunt. The phase shifts of otoacoustic emissions in response to body tilt were measured preoperatively, immediately postoperatively, and at 3-6 months, 7-15 months, 16-24 months, and more than 24 months postoperatively. Three groups were enrolled: Group 1, 19 patients who required no valve opening-pressure adjustment; Group 2, 18 patients who required valve opening-pressure adjustments; and Group 3, 7 patients who required valve replacement. RESULTS: In Group 1, phase shift, which was positive before surgery, became steadily negative after surgery and during the follow-up. In Group 2, phase shift, which was positive before surgery, became negative immediately after surgery and increasingly negative after a decrease in the valve-opening pressure. In Group 3, phase shift was positive in 6 cases and slightly negative in 1 case before revision, but after revision phase shift became significantly negative in all cases. CONCLUSIONS: Otoacoustic emissions noninvasively reflect cerebrospinal fluid shunt function and are impacted by valve-opening pressure adjustments. Otoacoustic emissions consistently diagnosed shunt malfunction and predicted the need for surgical revision. The authors' diagnostic test, which can be repeated without risk or discomfort by an unskilled operator, may address the crucial need of detecting valve dysfunction in patients with poor clinical outcome after shunt surgery.

The value of a rapid contrast-enhanced angio-MRI protocol in the detection of head and neck paragangliomas in SDHx mutations carriers: a retrospective study on behalf of the PGL.EVA investigators.

OBJECTIVES: To assess the performance of a simplified MRI protocol consisting of a contrast-enhanced three-dimensional MR angiography (CE-MRA) in association with a post-contrast T1-weighted sequence (T1WIV) for the detection of HNPGLs in SDHx mutation carriers. METHODS: This retrospective sub-study is based on the multicenter PGL.EVA cohort, which prospectively enrolled SDHx mutation carriers from 2005 to 2009; 157 index cases or relatives were included. CE-MRA and the T1WIV images were read solely with knowledge of the clinical data but blind to the diagnosis. Sensitivity, specificity and likelihood ratios for the simplified MRI protocol were compared to the full MRI protocol reading results and to the gold standard status obtained through the consensus of an expert committee. RESULTS: The sensitivity and specificity of the readings of the simplified MRI protocol were, respectively, 88.7 % (95 % CI = 78.1-95.3) and 93.7 % (95 % CI = 86.8-97.7) versus 80.7 % (95 % CI = 68.6-89.6) and 94.7 % (95 % CI = 88.1-98.3) for the readings of the full MRI protocol. CONCLUSIONS: The simplified post-contrast MRI with shorter duration (5 to 10 minutes) showed no performance difference compared to the lengthy standard full MRI and can be proposed for the detection of head and neck paragangliomas (HNPGLs) in SDHx mutation carriers. KEY POINTS: • Rapid angio-MRI protocol and the usual lengthy protocol show equal diagnostic performance. • The CE-MRA is the key sequence for the detection of HNPGLs. • The T1WIV sequence assists in localizing HNPGLs.

Cochlear implantation through the round window with a straight slotted electrode array: optimizing the surgical procedure.

The question addressed here is how optimizing the quality of insertion through the round window with the lower morbidity, when using a straight and slotted electrode array of regular length. This retrospective analysis includes all cases implanted with a cochlear implant Digisonic SP (Neurelec-Oticon Medical) since 2004. We checked the operative charts, the depth of insertion, and the follow-up. For comparisons, contingency tables were used and a Chi-square test was performed. A p value <0.05 was considered significant. 126 cases of patients with non-malformed cochleas were implanted through the round window. The mean age was 53.8 ± 16.2 for adults and 3.6 ± 2.6 for children (24 cases). The mean follow-up was 33 ± 22 months. The straight electrode array had either a square or a soft pointed tip (n = 84). Full insertion was achieved in 79 out of 84 cases with a soft tip vs. 18 out of 42 square tips (χ (2) = 41.41, DOF = 1, p < 0.0001). Two cases were stuck at the round window niche by a prominent crista fenestrae. In all cases but one, the chorda tympany was preserved. In one case, a misrouting to the vestibule required a revision surgery. Implantation through the round window with a straight and slotted electrode array with a soft tip (Digisonic SP, Neurelec-Oticon Medical) can lead to a full insertion in 94 % of cases. Drilling out a prominent crista fenestrae is recommended.

Anatomy of the Spinal Meninges.

BACKGROUND: The spinal meninges have received less attention than the cranial meninges in the literature, although several points remain debatable and poorly understood, like their phylogenesis, their development, and their interactions with the spinal cord. Their constancy among the chordates shows their crucial importance in central nervous system homeostasis and suggests a role far beyond mechanical protection of the neuraxis. OBJECTIVE: This work provides an extensive study of the spinal meninges, from an overview of their phylogenesis and embryology to a descriptive and topographic anatomy with clinical implications. It examines their involvement in spinal cord development, functioning, and repair. METHODS: This work is a review of the literature using PubMed as a search engine on Medline. RESULTS: The stages followed by the meninges along the phylogenesis could not be easily compared with their development in vertebrates for methodological aspects and convergence processes throughout evolution. The distinction between arachnoid and pia mater appeared controversial. Several points of descriptive anatomy remain debatable: the functional organization of the arterial network, and the venous and lymphatic drainages, considered differently by classical anatomic and neuroradiological approaches. Spinal meninges are involved in neurodevelopment and neurorepair producing neural stem cells and morphogens, in cerebrospinal fluid dynamics and neuraxis functioning by the synthesis of active molecules, and the elimination of waste products of central nervous system metabolism. CONCLUSION: The spinal meninges should be considered as dynamic functional formations evolving over a lifetime, with ultrastructural features and functional interactions with the neuraxis remaining not fully understood.

Use of a prototype radioprotection cabin in vascular neuroradiology: Dosimetry and ergonomics.

OBJECTIVES: The aim of this work was to compare the performance of a prototype radioprotection cabin in interventional neuroradiology, and to assess its suitability for routine use. MATERIALS AND METHODS: The radioprotection cabin was a prototype derived from the CATHPAX AF(®) model. Three operators carried out 21 procedures (19 brain arteriographies and 2 embolizations) using the radioprotection cabin and not wearing the usual lead individual protection equipment (IPE), and 17 procedures (16 brain arteriographies and 1 embolization) wearing the standard lead IPE (vest, skirt, thyroid shield and goggles), and not using the radioprotection cabin. In all cases, thermoluminescent dosimeters (TLDs) were positioned at head, trunk, pelvic region, and upper and lower limbs to measure the dose equivalent for Hp(0.07) or Hp(3) that they received, attenuated by either the cabin or the lead IPE. Parallel to these dosimetric measurements, the ergonomics of the protection cabin were appraised by each radiologist after each procedure. RESULTS AND CONCLUSION: The cabin procured an overall reduction of 74% of the dose received on the whole body with Hp(0.07)=0.04 mSv ± 0.01 (CL=95%) against Hp(0.07)=0.12 mSv ± 0.04 (CL=95%) for the IPE. Body protection with the cabin was near complete, and close to 100% for the regions not protected by the usual IPE (e.g. the head). We also showed that design weaknesses noted by the operators that hampered procedures (light reflections, reduced hand mobility, awkward access to radioscopy pedal) could be remedied by maker's improvements to the prototype and minor changes in work habits.

Interest of local intra-arterial fibrinolysis in acute central retinal artery occlusion: Clinical experience in 16 patients.

OBJECTIVE: Central retinal artery occlusion (CRAO) is a rare disease with poor visual prognosis. We evaluated clinical effectiveness of in situ fibrinolysis with original angiographic scores describing the aspect of carotid siphon, proximal ophthalmic artery, and choroid blush. METHODS: Retrospective study of 16 consecutive cases of CRAO between 2007 and 2013. Fourteen underwent in situ fibrinolysis, two were excluded due to pre-occlusive internal carotid stenosis on pre-procedural diagnostic angio-CT. Fibrinolysis was performed with rt-PA (average injected dose: 35 mg), with an average onset delay of 8hours (4-17h). We reported angiographic scores pre- and post-fibrinolysis, visual acuity (VA) before and after treatment, and VA improvement evaluated by ophthalmologist 6 to 12 months after thrombolysis. RESULTS: Six patients (43%) recovered post-fibrinolysis VA significally improved, superior or equal to 1/10 (1/10 to 8/10). An irregular carotid siphon (2 cases) appeared as a predictive factor of failure. Fibrinolysis procedure led to a significant improvement of angiographic permeability of proximal ophthalmic artery (P=0.0498), but this result was not accompanied by any VA improvement. The aspect of choroid blush showed no correlation with the management of thrombolysis. CONCLUSION: In situ fibrinolysis was more effective than medical treatments or natural evolution of CRAO (VA improvement was respectively 40% and 20%). However, the benefit/risk ratio must be discussed, and an angio-CT of supra-aortic trunks could be systematically performed before thrombolysis, to assess the potential VA recovery compared with complications such as ischemic stroke.

Vasospasm of labyrinthine artery in cerebellopontine angle surgery: evidence brought by distortion-product otoacoustic emissions.

In cerebellopontine angle (CPA) surgery, postoperative deafness can be due to alteration of cochlear blood flow that is supplied by the labyrinthine artery (LA). In particular, vasospasm is likely to occur and, if so, can be reversed. This work attempted to track down vascular events occurring during CPA surgery. Twenty consecutive patients with vestibular schwannoma were tested with useful preoperative hearing and presence of otoacoustic emissions (OAEs). Distortion-product otoacoustic emissions (DPOAEs), well-known to react within seconds to cochlear ischemia, were used intraoperatively to indirectly monitor cochlear blood flow. Continuous intraoperative monitoring of DPOAEs revealed three different time patterns associated with distinct auditory outcomes. Pattern P1-acute (n = 4) happened when the LA was severed: DPOAEs immediately and irreversibly foundered and led to postoperative deafness. Pattern P2-protracted (n = 7) revealed a progressive deterioration of DPOAEs from the beginning of tumor debulking, likely due to a steady decrease of cochlear blood flow, with postoperative deafness. Pattern P3-unstable (n = 5) corresponded to large DPOAE oscillations between their normal level and noise floor. It was due to acute LA vasospasm that could be reversed in three cases by topical nimodipin. Last, four patients had uneventful cochlear monitoring. In conclusion, cochlear ischemia can occur in vestibular schwannoma surgery, giving three different patterns among which vasospasm can be reversed if detected early.

Maps of the adult human hypothalamus.

The human hypothalamus is a small deeply located region placed at the crossroad of neurovegetative, neuroendocrine, limbic, and optic systems. Although deep brain stimulation techniques have proven that it could be feasible to modulate these systems, targeting the hypothalamus and in particular specific nuclei and white bundles, is still challenging. Our goal was to make a synthesis of relevant topographical data of the human hypothalamus, under the form of magnetic resonance imaging maps useful for mastering its elaborated structure as well as its neighborhood. As from 1.5 Tesla, Inversion-Recovery sequence allows locating the hypothalamus and most of its components. Spotting hypothalamic compartments is possible according to specific landmarks: the anterior commissure, the mammillary bodies, the preoptic recess, the infundibular recess, the crest between the preoptic and the infundibular recesses, the optical tract, the fornix, and the mammillo-thalamic bundle. The identification of hypothalamus and most of its components could be useful to allow the quantification of local pathological processes and to target specific circuitry to alleviate severe symptoms, using physical or biological agents.

Direct stereotactic targeting of the ventrointermediate nucleus of the thalamus based on anatomic 1.5-T MRI mapping with a white matter attenuated inversion recovery (WAIR) sequence.

BACKGROUND: The ventrointermediate nucleus (Vim) of the thalamus is still considered "invisible" on current magnetic resonance imaging (MRI), requiring indirect methods based on stereotactic atlases for estimation of its location. Direct visualization of Vim is desirable to improve targeting. OBJECTIVE: To evaluate the ability of Inversion-Recovery 1.5-T MR images to produce high-resolution, anatomical depiction of the thalamus suitable for direct Vim targeting. METHODS: Twenty patients with essential tremor or tremor associated with Parkinson's disease received Vim deep brain stimulation (DBS). Fahn-Tolosa-Marin and Unified Parkinson's Disease Rating Scale (UPDRS) tremor scores were assessed pre- and postoperatively. Preoperative stereotactic 1.5-T MR images of the thalamus were acquired using a White Matter Attenuated Inversion Recovery (WAIR) sequence. Thalamic nuclei were manually contoured on the basis of spontaneous MRI contrasts; labeling relied on 3D identification from stereotactic books and in-house ex vivo 4.7-T microscopic MRI atlas. Vim was then directly probed for electrophysiological confirmation and determination of the optimal site for electrode placement. RESULTS: The shape, spatial orientation, and signal contrast of Vim as depicted on our WAIR images were similar to those observed on the Schaltenbrand and Bailey atlas, as well as in our high-field MRI atlas. These images were successfully used for pure direct Vim targeting: at the last follow-up (median = 46.3 months), the average tremor score improved from 3.80 preoperatively to 0.50 postoperatively (on stimulation; P < 0.01). CONCLUSION: 1.5-T MRI with WAIR sequence provides high-quality images of Vim suitable in DBS surgery, for accurate preoperative planning, direct targeting and anatomic analysis.

Acute abscess of the base of the tongue: a rare but important emergency.

BACKGROUND: Acute posterior lingual abscess is rare, but may potentially compromise the airway acutely. OBJECTIVE: Lingual abscesses call for prompt and aggressive management because they are potentially life-threatening infections. Anterior lingual abscess (the most common) and posterior third lingual abscess must be differentiated. CASE REPORT: A young man who experienced the beginnings of dyspnea and total aphagia presented to the Emergency Department. A posterior lingual abscess was identified on computed tomography scan. DISCUSSION: Multi-antimicrobial therapy is the cornerstone of treatment. Surgical drainage is also of critical importance for preventing deeper spread of the infection. CONCLUSION: We present this case to increase awareness among emergency physicians and head and neck surgeons of the clinical findings of acute abscess of the base of the tongue, which can be difficult to diagnose clinically. Imaging of the oral cavity and pharynx is the key to the diagnosis, and the key to choosing the best surgical strategy.

Anatomy of the human thalamus based on spontaneous contrast and microscopic voxels in high-field magnetic resonance imaging.

BACKGROUND: Since the pioneering studies of human thalamic anatomy based on histology and binding techniques, little new work has been done to bring this knowledge into clinical practice. OBJECTIVE: With the advent of magnetic resonance imaging (MRI) we hypothesized that it was possible, in vitro, to make use of high spontaneous MRI contrasts between white and grey matter to directly identify the subcompartmentalisation of the thalamus. METHODS: An anatomic specimen was imaged at high field (4.7 T) (basal ganglia plus thalamus block; 3-dimensional (3D) T1-weighted spin echo sequence; matrix, 256 x 256 x 256; isotropic voxel, 0.250 mm/edge; total acquisition time, 14 hours 30 minutes). Nuclei were manually contoured on the basis of spontaneous contrasted structures; labeling relied on 3D identification from classic knowledge; stereotactic location of centers of nuclei was computed. RESULTS: Almost all intrathalamic substructures, nuclei, and white matter laminae were identified. Using 3D analysis, a simplified classification of intrathalamic nuclei into 9 groups was proposed, based on topographic MRI anatomy, designed for clinical practice: anterior (oral), posterior, dorsal, intermediate, ventral, medial, laminar, superficial, and related (epi and metathalamus). The overall 4.7-T anatomy matches that presented in the atlases of Schaltenbrand and Bailey (1959), Talairach et al (1957), and Morel et al (1997). CONCLUSION: It seems possible to identify the subcompartments of the thalamus by spontaneous MRI contrast, allowing a tissue architectural approach. In addition, the MRI tissue architecture matches the earlier subcompartmentalization based on cyto- and chemoarchitecture. This true 3D anatomic study of the thalamus may be useful in clinical neuroscience and neurosurgical applications.

Subthalamic nucleus location: relationships between stereotactic AC-PC-based diagrams and MRI anatomy-based contours.

Subthalamic nucleus (STN) targeting is classically performed based on AC-PC probabilistic position. Nevertheless, MRI allows direct visualization and targeting. We aimed to compare the position localized on MR images with standard stereotactic diagrams. The STN was manually contoured on MR images (22 Parkinson's disease patients); boundaries were simplified in a schematic polygonal form. Front and lateral stereotactic diagrams were constructed according to Talairach and Benabid. We compared x, y and z coordinates of the geometrical center of MRI-based polygons and stereotactic diagrams (Wilcoxon matched-pairs tests). There was significant discordance between MRI-based polygons and AC-PC-based images. MRI shows the STN as more posterior, medial and slightly inferior.

Contact position analysis of deep brain stimulation electrodes on post-operative CT images.

PURPOSE: Groups performing deep brain stimulation advocate post-operative imaging [magnetic resonance imaging (MRI) or computer tomography (CT)] to analyse the position of each electrode contact. The artefact of the Activa 3389 electrode had been described for MRI but not for CT. We undertook an electrode artefact analysis for CT imaging to obtain information on the artefact dimensions and related electrode contact positions. METHODS: The electrode was fixed on a phantom in a set position and six acquisitions were run (in-vitro study). The artefacts were compared with the real electrode position. Ten post-operative acquisitions were analysed (in-vivo analysis). We measured: H (height of the lateral black artefact), D (distance between the beginning of the white and the lateral black artefacts) and W (maximal artefact width), representing respectively the lengths of the four contacts and the electrode tip and width of the contact zone. A Student t-test compared the results: in vivo vs in vitro and coronal vs sagittal reconstructions along the electrode. RESULTS: The limits of the lateral black artefact around the electrode contacts corresponded to the final electrode position. There was no significant difference for D (in vivo, 1.1 +/- 0.1 mm; in vitro, 1.2 +/- 0.2 mm; p = 0.213), while W and H differed slightly (in vivo, W = 3.3 +/- 0.2 mm, H = 7.7 +/- 0.2 mm; in vitro, W = 3.1 +/- 0.1 mm, H = 7.5 +/- 0.2 mm). Results obtained with sagittal and coronal reconstructions were similar (p > 0.6). CONCLUSIONS: Precise three-dimensional (3D) localisation of the four-contact zone of the electrode can be obtained by CT identification of the limits of the lateral black artefact. The relative position of the four contacts is deduced from the size of the contacts and the inter-contact distance. Sagittal and coronal reconstructions along the electrode direction should be considered for the identification of the four electrode contacts. CT offers a useful alternative to post-operative MRI.

Brain mapping in stereotactic surgery: a brief overview from the probabilistic targeting to the patient-based anatomic mapping.

In this article, we briefly review the concept of brain mapping in stereotactic surgery taking into account recent advances in stereotactic imaging. The gold standard continues to rely on probabilistic and indirect targeting, relative to a stereotactic reference, i.e., mostly the anterior (AC) and the posterior (PC) commissures. The theoretical position of a target defined on an atlas is transposed into the stereotactic space of a patient's brain; final positioning depends on electrophysiological analysis. The method is also used to analyze final electrode or lesion position for a patient or group of patients, by projection on an atlas. Limitations are precision of definition of the AC-PC line, probabilistic location and reliability of the electrophysiological guidance. Advances in MR imaging, as from 1.5-T machines, make stereotactic references no longer mandatory and allow an anatomic mapping based on an individual patient's brain. Direct targeting is enabled by high-quality images, an advanced anatomic knowledge and dedicated surgical software. Labeling associated with manual segmentation can help for the position analysis along non-conventional, interpolated planes. Analysis of final electrode or lesion position, for a patient or group of patients, could benefit from the concept of membership, the attribution of a weighted membership degree to a contact or a structure according to its level of involvement. In the future, more powerful MRI machines, diffusion tensor imaging, tractography and computational modeling will further the understanding of anatomy and deep brain stimulation effects.

Rapidly developing leptomeningeal carcinomatosis following anterior skull base surgery: a case report.

Leptomeningeal carcinomatosis is rare in evolution of head and neck cancers. Prognosis is poor and treatment is through supportive care. We report an atypical rapid post-operative leptomeningeal carcinomatosis after skull base resection for an ethmoidal adenocarcinoma. The anterior skull base resection was near-total and we suspect a seeding of subarachnoid space either before surgery, either during surgical extirpation or from the residual intracranial nodule. It is the first description of rapid LMC after surgery (less than 1 month). Post-operative MRI diagnosed the LMC through the detection of contrast enhancing leptomeningeal nodules at bilateral second and eighth cranial nerves and at bilateral interpedoncular area. A strong index of suspicion along with clinical and radiological correlation is essential to arrive at a correct diagnosis. Otolaryngologists should be aware of the possibility of leptomeningeal carcinomatosis, before or after surgery, in a patient presents with an appropriate constellation of neurologic symptoms and a history of cancer.

A multicenter study of 705 ruptured intracranial aneurysms treated with Guglielmi detachable coils.

BACKGROUND AND PURPOSE: The long-term durability of Guglielmi detachable coil (GDC) embolization of cerebral aneurysms is still unknown. The purpose of this study was to evaluate the stability of anatomic occlusion of aneurysms treated with GDCs and assess the rate of recanalization and re-treatment. METHODS: A multicenter study involving 650 patients with 705 ruptured aneurysms treated with GDCs between January 1998 to May 2003 was conducted. During this period, 63% of ruptured aneurysms were treated by the endovascular technique. The morbidity and mortality associated with this technique, procedural feasibility, acute angiographic occlusion results, and long-term angiographic follow-up were assessed. RESULTS: Overall technical feasibility of GDC treatment was 96.9%. Upon admission, 25% of patients were Hunt and Hess grade IV or V. Acute angiographic results in 683 aneurysms demonstrated total occlusion in 496 cases (72.6%), subtotal occlusion in 171 cases (25.%), and incomplete occlusion in 16 cases (2.4%). All patients were controlled by angiography and MR imaging at 3 months, 1 year, and subsequent yearly examinations post-treatment. A second treatment was performed in 27 cases (recanalization, 4.7%). Long-term follow-up angiograms (mean, 36 months) were obtained in 571 aneurysms (95%). Of them, 422 aneurysms (73.9%) demonstrated complete occlusion, 148 aneurysms (25.9%) demonstrated subtotal occlusion, and only 1 aneurysm was incompletely occluded. Overall mortality was 11.4% for all patients, with procedural mortality evaluated at 1.4%. Overall morbidity was calculated at 8.6%. Only one rebleeding occurred in our study, with a second procedure performed without vital consequences for the patient. CONCLUSION: Our multicenter study confirms the stability of aneurysm embolization with GDC, with only 4.7% of aneurysms requiring re-treatment.