Roger Neves Mathias

Computed tomography evaluation of the normal craniocervical junction craniometry in 100 asymptomatic patients

OBJECT Most of the craniometric relationships of the normal craniocervical junction (CCJ), especially those related to angular craniometry, are still poorly studied and based on measurements taken from simple plain radiographs. In this study, the authors performed a craniometric evaluation of the CCJ in a population without known CCJ anomalies. The purpose of the study was to evaluate the normal CCJ craniometry based on measurements obtained from CT scans. METHOD The authors analyzed 100 consecutive CCJ CT scans obtained in adult patients who were admitted at their tertiary hospital for treatment of non-CCJ conditions between 2010 and 2012. A total of 17 craniometrical measurements were performed, including the relation of the odontoid with the cranial base, the atlantodental interval (ADI), the clivus length, the clivus-canal angle (CCA)-the angle formed by the clivus and the upper cervical spine, and the basal angle. RESULTS The mean age of the 100 patients was 50.6 years, and the group included 52 men (52%) and 48 women (48%). In 5 patients (5%), the tip of the odontoid process was more than 2 mm above the Chamberlain line, and in one of these 5 patients (1% of the study group). it was more than 5 mm above it. One patient had a Grabb-Oakes measurement above 9 mm (suggesting ventral cervicomedullary encroachment). The mean ADI value was 1.1 mm. The thickness of the external occipital protuberance ranged from 7.42 to 22.36 mm. The mean clivus length was 44.74 mm, the mean CCA was 153.68° (range 132.32°-173.95°), and the mean basal angle was 113.73° (ranging from 97.06°-133.26°). CONCLUSIONS The data obtained in this study can be useful for evaluating anomalies of the CCJ in comparison with normal parameters, potentially improving the diagnostic criteria of these anomalies. When evaluating CCJ malformations, one should take into account the normal ranges based on CT scans, with more precise bone landmarks, instead of those obtained from simple plain radiographs.

Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study

A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI). Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlains line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU), the mean distance of the tip of the odontoid process above the Chamberlains line was 12 mm versus 1.2 mm in the control (CO) group (p<0.0001). The number of patients with BI according to the threshold used (2, 5 or 6.6 mm) in the SU group was respectively 19 (95%), 16 (80%) and 15 (75%) and in the CO group it was 15 (37%), 4 (10%) and 2 (5%).

Superior sagittal sinus thrombosis as a treatment complication of nonsyndromic Kleeblattschädel.

A patient with nonsyndromic Kleeblattschädel, who underwent a craniotomy involving a constricting calvarial ring and frontal calvarial remodeling, developed a superior sagittal sinus thrombosis. The superior sagittal sinus venous outflow was obstructed as a consequence of the rapid brain expansion, along with a conflict of a remaining posterior bone crest. A successful second operation was performed to remove the posterior bone crest and facilitate the venous outflow. Meticulous preoperative planning should be carried out before addressing this complex craniofacial deformity.

Rare complication of ventriculoperitoneal shunt: Catheter protrusion to subcutaneous tissue - Case report

Background: Ventriculoperitoneal (VP) shunt is a day-to-day procedure performed by a neurosurgeon. The most frequent associated complications are obstructive and infectious. Although rare, there are well-reported complications related to the poor positioning of the distal catheter, with perforation of organs and tissues. Still rarer are the complications related to the migration of this catheter. Case Description: We describe an atypical case of VP shunt postoperative by normal pressure hydrocephalus. After well-documented proper positioning of the distal catheter into the intraperitoneal cavity, it protruded into the subcutaneous space. Even on a new documented satisfactory abdominal tomography, this catheter migrated back again to the subcutaneous tissue. Conclusion: We did not find plausible explanation for this rare event.

Is there a right time for surgery in paraplegic patients secondary to non traumatic spinal cord compression

Paraplegia is a well-defined state of complete motor deficit in lower limbs, regardless of sensory involvement. The cause of paraplegia usually guides treatment, however, some controversies remain about the time and benefits for spinal cord decompression in nontraumatic paraplegic patients, especially after 48 hours of the onset of paraplegia. The objective of this study was to evaluate the benefits of spinal cord decompression in such patients. We describe three patients with paraplegia secondary to non-traumatic spinal cord compression without sensory deficits, and who were surgically treated after more than 48 hours of the onset of symptoms. All patients, even those with paraplegia during more than 48 hours, had benefits from spinal cord decompression like recovery of gait ability. The duration of paraplegia, which influences prognosis, is not a contra-indication for surgery. The preservation of sensitivity in this group of patients should be considered as a positive prognostic factor when surgery is taken into account.

Fully Endoscopic Minimally Invasive Transrectus Capitis Posterior Muscle Triangle Approach to the Posterolateral Condyle and Jugular Tubercle

Background We evaluated a transrectus capitis posterior muscle triangle approach to the posterolateral foramen magnum, occipital condyles, jugular tubercle, and the fourth ventricle. We also assessed factors that affect the amount of bone removal required. Objective To evaluate if the proposed approach is as effective as standard open approaches to expose the lateral portion of the foramen magnum. Methods The proposed minimally invasive fully endoscopic approach was performed in 15 cadaveric specimens using 4‐mm (0‐ and 45‐degree) endoscopes. Results Using a 5‐cm straight paramedian incision, the rectus capitis posterior minor and major muscles were partially removed unilaterally, providing a corridor through the muscles to reach the foramen magnum region. After meticulous soft tissue dissection, key anatomical landmarks can be identified such as the greater occipital nerve, the vertebral artery that wraps around the atlanto‐occipital joint, and the bony protuberance that heralds the occipital condyle. A suboccipital craniotomy associated with the transcondylar, supracondylar or paracondylar approach is performed depending on the amount of bone removal desired to maximize the surgical view. By doing so, the jugular foramen can be exposed laterally as well as the fourth ventricle medially. Conclusion The proposed endoscopic approach can provide access through the transrectus capitis posterior muscle triangle leading directly to the occipital condyle. A stepwise approach is critical to gain a surgical corridor to the inferolateral petroclival region and the fourth ventricle.

3-D simulation of posterior fossa reduction in Chiari I

We proposed a 3D model to evaluate the role of platybasia and clivus length in the development of Chiari I (CI). Using a computer aided design software, two DICOM files of a normal CT scan and MR were used to simulate different clivus lengths (CL) and also different basal angles (BA). The final posterior fossa volume (PFV) was obtained for each variation and the percentage of the volumetric change was acquired with the same method. The initial normal values of CL and BA were 35.65 mm and 112.66º respectively, with a total PFV of 209 ml. Ranging the CL from 34.65 to 29.65 - 24.65 - 19.65, there was a PFV decrease of 0.47% - 1.12% - 1.69%, respectively. Ranging the BA from 122.66º to 127.66º - 142.66º, the PFV decreased 0.69% - 3.23%, respectively. Our model highlights the importance of the basal angle and clivus length to the development of CI.