Carlo Efisio Marras

Presurgical Functional MR Imaging of Language and Motor Functions: Validation with Intraoperative Electrocortical Mapping

PURPOSE To prospectively determine the sensitivity and specificity of functional magnetic resonance (MR) imaging for mapping language and motor functions in patients with a focal mass adjacent to eloquent cortex, by using intraoperative electrocortical mapping (ECM) as the reference standard. MATERIALS AND METHODS The ethics committee approved the study, and patients gave written informed consent. Thirty-four consecutive patients (16 women, 18 men; mean age, 43.2 years) were included who met the following three criteria: They had a focal mass in or adjacent to eloquent cortex of the language or motor system, they had the ability to perform the functional MR imaging task, and they had to undergo surgery with intraoperative ECM. Functional MR imaging with verb generation (n = 17) or finger tapping of the contralateral hand (n = 17) was performed at 1.5 T with a block design and an echo-planar gradient-echo T2*-weighted sequence. Cortex essential for language or hand motor functions was mapped with ECM. A site-by-site comparison between functional MR imaging and ECM was performed with the aid of a neuronavigational device. Sensitivity and specificity were calculated according to task performed, histopathologic findings, and tumor grade. Exact 95% confidence intervals were calculated for each sensitivity and specificity value. RESULTS For 34 consecutive patients, there were 28 with gliomas, two with metastases, one with meningioma, and three with cavernous angiomas. A total of 251 cortical sites were tested with ECM; overall functional MR imaging sensitivity and specificity were 83% and 82%, respectively. Sensitivity (65%) was lower and specificity (93%) was higher in World Health Organization grade IV gliomas compared with grade II (sensitivity, 93%; specificity, 79%) and III (sensitivity, 93%; specificity, 76%) gliomas. At 3 months after surgery, language proficiency was unchanged in 15 patients; functionality of the contralateral arm was unchanged in 14 patients and improved in one patient. CONCLUSION Functional MR imaging is a sensitive and specific method for mapping language and motor functions.

Stimulation of the globus pallidus internus for childhood-onset dystonia

We report the results of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in 12 patients with childhood‐onset generalized dystonia refractory to medication, including 3 patients with status dystonicus. There were 8 patients who had DYT1‐negative primary dystonia, 1 had DYT1‐positive dystonia, and 3 had symptomatic dystonia. Stimulation was effective in all but 1 patient. Dystonic postures and movements of the axis and limbs responded to DBS to a greater extent than oromandibular dystonia and fixed dystonic postures. These findings provide further evidence that pallidal stimulation is an effective treatment for intractable childhood‐onset dystonia, including status dystonicus, and together with previous findings, suggest that it should be considered the treatment of choice for these conditions.

Cerebral cavernomas and seizures: a retrospective study on 163 patients who underwent pure lesionectomy.

The objective was to evaluate the outcome of microsurgical “pure” lesionectomy in patients with supratentorial cavernous angiomas presenting with seizures. For this retrospective study 163 patients with cavernoma-related epileptic seizures were selected. They all underwent surgery in a single institution between 1988 and 2003. A microsurgical frame/frameless guided minimally invasive transulcal “pure” lesionectomy was performed. The haemosiderin stained gliotic brain parenchyma that was usually found surrounding the lesion was not removed. Among the 99 patients with epilepsy and longer clinical history, 68 (68.7%) were found completely to be seizure-free, 10 (10.1%) presented sporadic and less frequent seizures and 17 (17.1%) remained unchanged. Sixty-three out of 64 (98.4%) patients who experienced only single or sporadic seizures were found to be completely seizure-free after surgery. Five patients were lost at follow-up (mean 48 months, range 0.5–14 years). Long-term morbidity was 1.8%. Mortality was null. No haemorrhagic episodes were observed during follow-up. Pure lesionectomy prevents bleeding and development of epilepsy in patients that receive early surgery after the epileptic onset. In most of the epileptic patients with a good concordance between the electroclinical data and the location of the angioma, good results can be achieved by this kind of surgery so that more invasive and costly studies to find and remove the epileptogenic cerebral parenchyma seem justified only after lesionectomy fails.

Stimulation of the Posterior Hypothalamus for Medically Intractable Impulsive and Violent Behavior

Objective: To describe the therapeutic effect of deep brain stimulation for the treatment of patients with below-average IQs who are affected by aggressive and disruptive behavior and who are resistant to any drug and/or conservative treatment (including occupational therapy). Patients and Methods: Two consecutive patients suffering from mental retardation with aggressive and disruptive behavior and resistant to any pharmacological treatment underwent deep brain stimulation electrode placement in the posteromedial hypothalamus for continuous chronic high-frequency stimulation (HFS). The stereotactic coordinates of the target were chosen according to the study by Sano et al., which involved hypothalamic stereotactic lesions. Results: HFS of the posteromedial hypothalamus demonstrated consistent improvement of disruptive behavior in both patients at the follow-up evaluation 1 year later. Conclusions: HFS of the posteromedial hypothalamus showed similar results to those obtained by Sano et al. in the 1960s with radiofrequency lesions of the same target volume. The reversibility of neurostimulation allows HFS to control disruptive behavior when conservative treatments are ineffective, and drug therapy is uneventful or causes severe side effects. In conclusion, this neuromodulation procedure improved the quality of life and the range of social relationships for both of the treated patients.

A Simple Method to Assess Accuracy of Deep Brain Stimulation Electrode Placement: Pre-Operative Stereotactic CT + Postoperative MR Image Fusion

Objective: To describe a method for the measurement of the accuracy of deep brain stimulation (DBS) electrode placement with the use of image fusion technologies. Patients and Methods: Ten consecutive patients suffering from movement disorders underwent DBS electrode placement. Postoperative MR images were fused with the pre-operative stereotactic CT. The placement error in the anteroposterior, lateral and vertical planes was calculated. Results: The anteroposterior mean error ± SD was 0.61 ± 0.22 mm (range 0.2–0.9 mm). The lateral mean error ± SD was 0.65 ± 0.27 mm (range 0.2–2.2 mm). The vertical mean error ± SD was 0.82 ± 0.31 mm (range 0.3–1.6 mm). Conclusions: This technique provides a simple and precise method for the evaluation of the accuracy of DBS electrode placement.

Deep Brain Stimulation of Two Unconventional Targets in Refractory Non-Resectable Epilepsy

Introduction: Several deep brain targets have been assessed for the treatment of unresectable refractory epileptic conditions. Adrian Upton in 1985 proposed deep brain stimulation (DBS) of the anterior nucleus of the thalamus for the treatment of seizures and psychosis [Cooper I.S., Upton A.R.: Biol Psychiatry 1985;20:811–813]. Francisco Velasco, in 1987, introduced DBS of the thalamic centromedian nucleus, proposing its employment for Lennox-Gastaut syndrome and for multifocal epilepsy. Other proposed targets are the subthalamic nucleus, caudate nucleus, Forel fields and mammillothalamic tract. We employed DBS for stimulating 2 ‘unconventional targets’, the posterior hypothalamus (pHyp) and caudal zona incerta (CZi), for the treatment of 2 patients with multifocal epilepsy and behavioural comorbidity, and 2 patients with sensorimotor focal seizures, respectively. Such patients did not meet criteria for resective surgery. Material and Methods: In our institution, between January 2003 and May 2004, we started DBS in 2 epileptic patients The former patient was affected by multifocal epilepsy, and the second one by refractory partial motor and secondary generalized seizures. The chosen targets were the pHyp in the former case and the CZi in the latter. The encouraging results obtained led us to replicate such a favourable experience in 2 more patients, 1 with focal motor epilepsy once again (resulting in status epilepticus) and the other with behavioural comorbidity and multifocal epilepsy. Results: A significant reduction in seizure frequency was observed, and the 2 patients with behavioural comorbidity also showed a dramatic improvement in their disruptive behaviour. The patient with motor focal seizures showed a 70% reduction in seizure frequency, and in the last patient remission from status epilepticus was obtained. Conclusion: Our data confirm DBSof deep brain structures modulates the functional activity of the cerebral cortex as suggested by Adrian Upton in 1985. In the reported series, deep-brain stimulation of 2 unconventional targets belonging to the reticulo-cortical system (the brainstem-diencephalon functional system including structures that act as remote controls in modulating cortical excitability) was found to be effective in controlling otherwise refractory multifocal (pHyp) and focal sensorimotor (CZi) epilepsy when resective surgery was not feasible.

Chronic motor cortex stimulation for movement disorders: A promising perspective

Abstract Five patients affected by thalamic hand and intentional myoclonus have been evaluated and selected for chronic motor cortex stimulation. A quadripolar electrode strip was placed epidurally under local anesthesia through an MR-image-guided single precentral burr hole placed following the morphologic recognition of the central sulcus. Intra-operative stimulation was used to induce muscle contraction at the affected site to confirm the correct placement of the electrode. A one-week trial period preceded the implant of an internal pace-maker under general anesthesia. A remarkable decrease in pain was reported by four patients together with the reduction of dystonia and rigidity in thalamic hand and marked decrease of intentional myoclonus. No complications or undesired side effects of electrode implant and stimulation were observed.

Huge epidural hematoma after surgery for spinal cord stimulation

SummaryObjective and importance. Spinal epidural haematoma (SEH) following implantation of an epidural spinal cord electrode is a very rare complication but one that must not be overlooked. This case is unusual because of the almost “holocord” extension of the haematoma and the excellent recovery obtained by prompt surgical treatment.Clinical presentation. A 69 years old man with normal serum coagulation parameters was submitted to spinal cord stimulation (SCS) for chronic pain syndrome. After a minimal L1 laminotomy the patient developed paraplegia due to a large haematoma at D4-L2.Intervention. Surgical removal of the entire clot by a D4-L2 laminectomy was performed immediately.Conclusion. Large epidural haematoma can result from SCS and this complication may be cured by appropriate and prompt surgery.

CyberKnife radiosurgery as a first treatment for idiopathic trigeminal neuralgia.

OBJECTIVETo report the level of effectiveness and safety, in our experience, of CyberKnife (Accuray, Inc., Sunnyvale, CA) robotic radiosurgery as a first-line treatment against pharmacologically refractory trigeminal neuralgia. METHODSWe treated 33 patients with the frameless CyberKnife system as a monotherapy. The retrogasserian portion of the trigeminal nerve (a length of 4 mm, 2–3 mm anterior to the root entry zone) was targeted. Doses of 55 to 75 Gy were prescribed to the 100% isodose line, according to a dose escalation protocol. The patients were evaluated for the level of pain control, time to pain relief, hypesthesia, and time to pain recurrence. RESULTSThe median age was 74 years. All but 2 patients (94%) achieved a successful treatment outcome. The follow-up period was 9 to 37 months (mean, 23 months). The Barrow Neurological Institute Pain Intensity Scale (BPS) score before radiosurgery was III in 2 patients (6%), IV in 8 patients (24%), and V in 23 patients (70%). The time to pain relief was 1 to 180 days (median, 30 days). No facial numbness was observed. Only 1 patient developed a transitory dysesthesia of the tongue. After treatment, the BPS score was I, II, or III in 31 patients (97%). Pain recurred in 33% (11 patients) at a mean of 9 months (range, 1–43 months). Three patients with recurrences had low pain control by medication (BPS score, IV), and 1 patient (BPS score, V) needed a radiofrequency lesioning (BPS score, I at 12 months). CONCLUSIONCyberKnife radiosurgery for trigeminal neuralgia allows pain relief at safe doses and is suggested for pharmacologically refractory trigeminal neuralgia. Higher prescribed doses were not associated with improvement in pain relief or recurrence rate.OBJECTIVE To report the level of effectiveness and safety, in our experience, of CyberKnife (Accuray, Inc., Sunnyvale, CA) robotic radiosurgery as a first-line treatment against pharmacologically refractory trigeminal neuralgia. METHODS We treated 33 patients with the frameless CyberKnife system as a monotherapy. The retrogasserian portion of the trigeminal nerve (a length of 4 mm, 2-3 mm anterior to the root entry zone) was targeted. Doses of 55 to 75 Gy were prescribed to the 100% isodose line, according to a dose escalation protocol. The patients were evaluated for the level of pain control, time to pain relief, hypesthesia, and time to pain recurrence. RESULTS The median age was 74 years. All but 2 patients (94%) achieved a successful treatment outcome. The follow-up period was 9 to 37 months (mean, 23 months). The Barrow Neurological Institute Pain Intensity Scale (BPS) score before radiosurgery was III in 2 patients (6%), IV in 8 patients (24%), and V in 23 patients (70%). The time to pain relief was 1 to 180 days (median, 30 days). No facial numbness was observed. Only 1 patient developed a transitory dysesthesia of the tongue. After treatment, the BPS score was I, II, or III in 31 patients (97%). Pain recurred in 33% (11 patients) at a mean of 9 months (range, 1-43 months). Three patients with recurrences had low pain control by medication (BPS score, IV), and 1 patient (BPS score, V) needed a radiofrequency lesioning (BPS score, I at 12 months). CONCLUSION CyberKnife radiosurgery for trigeminal neuralgia allows pain relief at safe doses and is suggested for pharmacologically refractory trigeminal neuralgia. Higher prescribed doses were not associated with improvement in pain relief or recurrence rate.

Anatomo-functional study of the temporo-parieto-occipital region: dissection, tractographic and brain mapping evidence from a neurosurgical perspective.

The temporo‐parieto‐occipital (TPO) junction is a complex brain territory heavily involved in several high‐level neurological functions, such as language, visuo‐spatial recognition, writing, reading, symbol processing, calculation, self‐processing, working memory, musical memory, and face and object recognition. Recent studies indicate that this area is covered by a thick network of white matter (WM) connections, which provide efficient and multimodal integration of information between both local and distant cortical nodes. It is important for neurosurgeons to have good knowledge of the three‐dimensional subcortical organisation of this highly connected region to minimise post‐operative permanent deficits. The aim of this dissection study was to highlight the subcortical functional anatomy from a topographical surgical perspective. Eight human hemispheres (four left, four right) obtained from four human cadavers were dissected according to Klinglers technique. Proceeding latero‐medially, the authors describe the anatomical courses of and the relationships between the main pathways crossing the TPO. The results obtained from dissection were first integrated with diffusion tensor imaging reconstructions and subsequently with functional data obtained from three surgical cases, all resection of infiltrating glial tumours using direct electrical mapping in awake patients. The subcortical limits for performing safe lesionectomies within the TPO region are as follows: within the parietal region, the anterior horizontal part of the superior longitudinal fasciculus and, more deeply, the arcuate fasciculus; dorsally, the vertical projective thalamo‐cortical fibres. For lesions located within the temporal and occipital lobes, the resection should be tailored according to the orientation of the horizontal associative pathways (the inferior fronto‐occipital fascicle, inferior longitudinal fascicle and optic radiation). The relationships between the WM tracts and the ventricle system were also examined. These results indicate that a detailed anatomo‐functional awareness of the WM architecture within the TPO area is mandatory when approaching intrinsic brain lesions to optimise surgical results and to minimise post‐operative morbidity.