A. Fichten

Frameless robotic stereotactic biopsies: a consecutive series of 100 cases

OBJECT Stereotactic biopsy procedures are an everyday part of neurosurgery. The procedure provides an accurate histological diagnosis with the least possible morbidity. Robotic stereotactic biopsy needs to be an accurate, safe, frameless, and rapid technique. This article reports the clinical results of a series of 100 frameless robotic biopsies using a Medtech ROSA device. METHODS The authors retrospectively analyzed their first 100 frameless stereotactic biopsies performed with the robotic ROSA device: 84 biopsies were performed by frameless robotic surface registration, 7 were performed by robotic bone fiducial marker registration, and 9 were performed by scalp fiducial marker registration. Intraoperative flat-panel CT scanning was performed concomitantly in 25 cases. The operative details of the robotic biopsies, the diagnostic yield, and mortality and morbidity data observed in this series are reported. RESULTS A histological diagnosis was established in 97 patients. No deaths or permanent morbidity related to surgery were observed. Six patients experienced transient neurological worsening. Six cases of bleeding within the lesion or along the biopsy trajectory were observed on postoperative CT scans but were associated with transient clinical symptoms in only 2 cases. Stereotactic surgery was performed with patients in the supine position in 93 cases and in the prone position in 7 cases. The use of fiducial markers was reserved for posterior fossa biopsy via a transcerebellar approach, via an occipital approach, or for pediatric biopsy. CONCLUSIONS ROSA frameless stereotactic biopsies appear to be accurate and safe robotized frameless procedures.

Perfusion MRI as a Neurosurgical Tool for Improved Targeting in Stereotactic Tumor Biopsies

Objective: Stereotactic biopsies are subject to sampling errors (essentially due to target selection). The presence of contrast enhancement is not a reliable marker of malignancy. The goal of the present study was to determine whether perfusion-weighted imaging can improve target selection in stereotactic biopsies. Methods: We studied 21 consecutive stereotactic biopsies between June 2009 and March 2010. Perfusion-weighted magnetic resonance imaging (MRI) was integrated into our neuronavigator. Perfusion-weighted imaging was used as an adjunct to conventional MRI data for target determination. Conventional MRI alone was used to determine the trajectory. Results: We found a linear correlation between regional cerebral blood volume (rCBV) and vessel density (number of vessels per mm2; R = 0.64; p < 0.001). Perfusion-weighted imaging facilitated target determination in 11 cases (52.4%), all of which were histopathologically diagnosed as glial tumors. For glial tumors, which presented with contrast enhancement, perfusion-weighted imaging identified a more precisely delimited target in 9 cases, a different target in 1 case, and exactly the same target in 1 other case. In all cases, perfusion-selected sampling provided information on cellular features and tumor grading. rCBV was significantly associated with grading (p < 0.01), endothelial proliferation (p < 0.01), and vessel density (p < 0.01). For lesions with rCBV values ≤1, perfusion-weighted MRI did not help to determine the target but was useful for surgical management. Conclusions: For stereotactic biopsies, targeting based on perfusion-weighted imaging is a feasible method for reducing the sampling error and improving target selection in the histopathological diagnosis of tumors with high rCBVs.

Correlation between tap test and CSF aqueductal stroke volume in idiopathic normal pressure hydrocephalus.

INTRODUCTION The diagnosis and management of idiopathic normal pressure hydrocephalus (INPH) remains unclear despite the development of guidelines. In addition, the role of cerebrospinal fluid (CSF) aqueductal stroke volume (ASV) remains unspecified. OBJECTIVES The aim of this study was to compare the results of the tap test (TT) and ASV in patients with possible INPH. MATERIALS AND METHODS Among 21 patients investigated with both TT and phase-contrast (PC) MRI, we identified two groups, with either (1) a positive TT (PTT) or (2) a negative one (NTT), and we compared their ASV as measured by PC-MRI. ASV cutoff value was set at 70 μL/cardiac cycle (mean value +2 standard deviations in age-matched healthy subjects). RESULTS In the PTT group (n = 9), the mean ASV was 175 ± 71 μL. Among these patients, four were shunted, and improved after surgery. In the NTT group, two patients were finally diagnosed with aqueductal stenosis and excluded. Among the remaining patients (n = 10), the mean ASV was 96 ± 93 μL (p < 0.05). However, three of these patients presented with hyperdynamic ASV, and an associated neurodegenerative disorder was diagnosed. Two patients had ventriculoperitoneal shunting despite their NTT, and improved. DISCUSSION/CONCLUSIONS In our patient population, the noninvasive measurement of hyperdynamic ASV correlated with PTT, suggesting PC-MRI could be utilized to select those patients who would benefit from shunting. ASV may therefore be an interesting supplemental diagnosis tool.

Fracture de l'odontoïde chez le sujet de plus de 70 ans: morbidité, handicap et place du traitement chirurgical. À propos d'une série de 27 patients

BACKGROUND AND PURPOSE Odontoid process fractures of the axis are frequent in elderly patients. However, the impact in terms of handicap and morbidity in this particular population are unknown. The role of surgical treatment remains controversial. METHODS We present a retrospective series of patients aged 70 years or older with odontoid fractures treated in our department between 1998 and 2006. Two cohorts were defined (surgery versus conservative) and compared. Morbidity, handicap, and radiographic fusion were analyzed. RESULTS Twenty-seven patients were treated. The mean age was 80.67 years. Five patients died early during hospitalization. Fractures were type II in 66.7% of the cases and type III in 33.3%. Orthopedic treatment was chosen in 44.4% of the cases. A non-union at the fracture site was found in 33% of the cases and morbidity in 41.7% of the cases was found after a 1-year follow-up. Surgery was performed in 40.7% of the cases. There was 18% non-union and no morbidity after 1-year of follow-up. Morbidity was statistically lower in the surgery group (p=0.037), particularly in cases of type II fracture (p=0.0063); no statistically significant difference was found for non-union at the fracture site (p=0.64) except for type II fractures (p=0.028). CONCLUSIONS Odontoid fractures in the elderly are a very frequent problem. Immediate mortality is still high but appears correlated to associated lesions. Todays treatments must preserve autonomy for these patients. For elderly patients, the treatment must be chosen in relation to the fracture analysis. In our opinion, surgical management is the treatment of choice for unstable fractures (type II). Conservative management is indicated for stable fractures.

Effect of surgery on periventricular white matter in normal pressure hydrocephalus patients: comparison of two methods of DTI analysis

Background Diffusion tensor imaging (DTI) is a useful tool for assessing changes that occur in microstructures. We have developed a novel method for region of interest (ROI) delineation in the assessment of DTI parameters in patients with normal pressure hydrocephalus (NPH). Purpose To compare the standard method and our novel method in an evaluation of the impact of surgery on periventricular white matter in patients with NPH. Material and Methods Ten patients with NPH underwent 3T magnetic resonance imaging (MRI; including 12-direction DTI sequences) before and after surgery. We recorded diffusion parameters (λi, the fractional anisotropy [FA], the apparent diffusion coefficient, and Dr) in the internal capsule (IC) and the body of the corpus callosum (BCC). Using the standard delineation technique, regions of interest (ROIs) were positioned according to anatomical and functional considerations and then filled with several sub-ROIs. The ROIs delineated with our novel technique (extracted as the six sub-ROIs with the lowest standard deviation for the FA) were arranged in two rows (medial and lateral), from the ventricle to the brain surface. Results The within-ROI homogeneity was higher with the novel method than with the conventional method (P < 10−4). When the conventional delineation method was applied to the IC data, only λ2 was found to be significantly greater after surgery; in contrast, application of our novel method evidenced a significant decrease in FA and λ1 and a significant increase in λ2 (P < 0.05). Both before and after surgery, the FA in the medial row of ROIs was greater than the FA in the lateral row (P < 0.01). In the BCC, only λ2 and Dr varied significantly (when evaluated with the novel method). Conclusion Our results show that use of a novel method of DTI data analysis may be more sensitive to local changes induced by surgical procedures. Furthermore, this novel method was able to detect the transmantle pressure gradient related to the regional stress distribution.

Non-traumatic pseudocyst of Glisson capsule complicating a ventriculoperitoneal shunt

BACKGROUND Cerebrospinal fluid pseudocysts in the peritoneal cavity following ventriculoperitoneal shunt are relatively uncommon. In these complications, perforation of solid organs is unusual. CASE DESCRIPTION A case of subcapsular hepatic pseudocyst is described. A 48-year-old man treated by ventriculoperitoneal shunt presented with abdominal pain. Laboratory examinations revealed hepatic cytolysis. The CT-scan of the abdomen demonstrated a small ovoid non-enhanced cystic collection in the subcapsular area of hepatic segment V. Percutaneous hepatic fine-needle aspiration of the cyst guided by abdominal ultrasonography showed no abnormal findings. Peritoneal reimplantation at a different site was performed. The clinicopathological features of this entity are described and treatments are discussed. CONCLUSION Reinsertion of the catheter at a different abdominal site is effective in non-infections cases. In contrast, a temporary external drainage with adequate antibiotic treatment followed by shunt reinsertion is necessary to treat a documented infection of CSF collections.

Should we fear cement leakage during kyphoplasty in percutaneous traumatic spine surgery? A single experience with 76 consecutive cases

OBJECTIVE Although kyphoplasty is widely used to repair osteoporotic and pathologic vertebral fractures, balloon kyphoplasty and vertebral body stenting are new treatment options in cases of traumatic spinal injury. To our knowledge, there are no literature data on the incidence of cement leakage whereas these two percutaneous techniques are commonly used to repair non-pathologic fractures. The aim of this study was to evaluate and compare the clinical characteristics and the incidence of cement leakage associated with balloon kyphoplasty and vertebral body stenting in the percutaneous treatment of traumatic spinal injury. METHODS A series of 76 consecutive kyphoplasties (50 with vertebral body stenting and 26 balloon kyphoplasties) were retrospectively reviewed. Preoperative and postoperative computed tomography scans were analyzed in order to detect cement leakage and grade it as minor, moderate or major. RESULTS The overall leakage rate was 50%. None of the leakages gave rise to clinical symptoms. Although balloon kyphoplasty and vertebral body stenting did not differ in terms of the leakage rate, the latter technique was associated with a lower leakage volume. The Magerl type, fracture level and use of concomitant osteosynthesis did not appear to significantly influence the leakage rate. CONCLUSION Vertebral body stenting can reduce the amount of cement leakage due to a better cohesion of the bone fragments after kyphosis correction and maintenance.

Dual, minimally invasive fixation in acute, double, thoracic spine fracture.

BACKGROUND We report on a dual percutaneous fixation in 2 patients with a double thoracic spine fracture. The advantages and limitations of this new approach for treating traumatic spinal fractures are reviewed. CLINICAL PRESENTATION A 67-year-old male was admitted following a fall from a height of 3 m. A neurological examination revealed sub-T11 motor and sensory paraparesis. There were a T6 vertical body and bi-articular fracture and a T11 vertebral burst fracture with > 75% posterior wall damage. A 40-year-old male was admitted after a suicide attempt. A neurological examination revealed sub-T11 paraplegia. There were a T7 vertebral body fracture with intact posterior wall and a T11 burst fracture with > 75% posterior wall damage. SURGICAL TECHNIQUE The same technique was used in both cases. 2 minimally invasive percutaneous fixations of the 2 fractures were performed. In a third step, we performed a T10-T12 open laminectomy. This technique helped to limit blood loss and avoid an over-long fixation. Pedicle screw targeting was optimal. 16 months later, the neurological status was normal in patient 1 and there was neurological improvement in patient 2. No secondary segmental kyphotic deformities appeared.Percutaneous fixation enables the treatment of an acute thoracic spine fracture. With appropriate presurgical planning, this technique can be applied to all thoracic vertebrae. Spinal cord injuries justify the use of laminectomy together with percutaneous fixation, in order to limit erector muscle injury and blood loss.

Tension pneumocephalus and rhinorrhea revealing spontaneous cerebrospinal fluid fistula of the anterior cranial base

Spontaneous cerebrospinal fluid fistulas (CSFFs) of the anterior skull base are extremely rare. We report a case of spontaneous CSFF of the ethmoid cribriform plate presenting with rhinorrhea and tension pneumocephalus. We discuss the physiopathology, the radiological management, and the treatment of spontaneous CSF fistulas related to the anterior skull base. A 58-year-old woman was admitted to our institution for headaches with clear rhinorrhea persisting over several days. Antecedents were unremarkable. An episode of epistaxis three days before was reported. Clinical examination showed clear rhinorrhea, headaches, and anosmia. The CT scan showed voluminous epidural and subdural pneumocephalus with mass effect on both frontal and temporal lobes. A high-resolution CT scan with bone reconstruction showed a 2-mm bony defect of the cribriform plate. Surgery consisted of epidural frontal anterior skull base repair. Postsurgery follow-up was uneventful. At one year, the patient was asymptomatic apart from the persistence of anosmia. Spontaneous CSF fistulas are uncommon and can be associated with tension pneumocephalus. The physiopathology remains unclear. Their treatment by complete exclusion of the fistula is necessary because of the lethal risk of pneumococcus meningitis.

Odontoid fracture complicating Jaffe-Lichtenstein disease. Case report.

The authors report the case of a 31-year-old man with polyostotic fibrous dysplasia who suffered a traumatic odontoid fracture in an area of a preexisting bone lesion. Conservative treatment was successfully performed. Jaffe-Lichtenstein disease is discussed along with differential diagnoses and alternative methods of treatment.