The M-Point A Novel Landmark in Middle Fossa Surgery: A Cadaveric Morphometric Study.

BACKGROUND: The arcuate eminence (AE) is an anatomically consistent bony protrusion located on the upper surface of the petrous bone that has been previously studied as a reference for lateral skull base approaches. There is a paucity of information in the neurosurgical literature seeking to improve the safety of the extended middle cranial fossa (MCF) approach using detailed morphometric analysis of the AE. OBJECTIVE: To evaluate the use of the AE as an anatomical landmark to help with early identification of the internal acoustic canal (IAC) in MCF approaches by means of a cadaveric study, using a new morphometric reference termed the "M-point." METHODS: A total of 40 dry temporal bones and 2 formalin-preserved, latex-injected cadaveric heads were used. The M-point was established as a new anatomic reference by identifying the intersection of a line perpendicular to the alignment of the petrous ridge (PR), originating from the midpoint of the AE, with the PR itself. Subsequent anatomical measurements were performed to measure the distance between M-point and IAC. Additional distances, including PR length and the anteroposterior and lateral AE surfaces, were also measured. RESULTS: The mean distance between the M-point and the center of the IAC was 14.9 mm (SD ± 2.09), offering a safe drilling area during an MCF approach. CONCLUSIONS: This study provides novel information on identification of a new anatomic reference point known as the M-point that that can be used to improve early surgical identification of the IAC.

Anatomical Basis of the Zygomatic-Transmandibular Approach: Operative Video.

Tumor growth in infratemporal fossa (ITF) and parapharyngeal space (PPS) is generally slow and generates very few clinical manifestations, so it is not uncommon for tumors to reach large dimensions at the time of diagnosis, making necessary to perform ample approaches. In zygomatic-transmandibular approach (ZTMA), the access of the ITF and PPS is obtained by a combination of a pterional craniotomy plus a zygomatic-mandibular osteotomy. Tumor excision is achieved by its initial dissection from all of the neurovascular structures of the middle fossa by the neurosurgical team and the final resection by the head and neck team from below. In the first part of this video, we present a brief anatomical-surgical description of the ITF and PPS and in the second part, we show case of a trigeminal schwannoma that could be successfully removed through a ZTMA. Using this approach, an ample and safe exposure of the ITF and PPS is achieved, without affecting the chewing or facial nerve function and with excellent cosmetic results, so it can be considered as a reliable surgical option, particularly in cases of giant tumors that affect these regions ( Figs. 1 and 2 ). The link to the video can be found at: https://youtu.be/oxVFhzT8HsQ .

Extradural Devascularization for Resection of a Lesser Sphenoid Wing Meningioma: 2-Dimensional Operative Video.

We describe the case of a 42-yr-old female patient with a 2-yr history of headache that has progressively worsened. Physical examination revealed no neurological deficit. Magnetic resonance imaging showed a large tumor of the left lesser sphenoid wing that enhanced with gadolinium and produced displacement of the midline and the Sylvian fissure. A thorough analysis of the origin of the tumor was done to establish the surgical strategy. With the patient positioned supine with the head slightly turned to the right side, fixed in a 3-pin head clamp, a pterional craniotomy was performed. Since the origin of the tumor is in the lesser wing an early extradural devascularization of the tumor was done with drilling out all the hyperostotic bone of the lesser sphenoid wing, including the lateral base of the anterior clinoid process. Intradural debulking and resection showed the effect of extradural devascularization with an important decrease in bleeding, allowing the total resection of the tumor. An immediate postop magnetic resonance showed a complete removal of the tumor. The patient presented a paresis of the oculomotor nerve that completely resolved in the 3-mo follow-up. In the following video illustration, we narrate this operative case and highlight the nuances of this approach.1 The patient has given assent and written consent for videos, images, or clinical or genetic information to be published.

Bobble-head doll syndrome in an 80-year-old man, associated with a giant arachnoid cyst of the lamina quadrigemina, treated with endoscopic ventriculocystocisternotomy and cystoperitoneal shunt.

Bobble-head doll syndrome (BHDS) is a rare entity, characterized by antero-posterior head bobbing, which is of the type "yes-yes." Less frequently, having a head movement of the type "no-no" is described. We report an unusual case of an 80-year-old man with a cystic mass of the lamina quadrigemina, extending to the posterior fossa. We conclude that ventriculocystocisternotomy associated with a cystoperitoneal shunt is an effective treatment for a symptomatic giant arachnoid cyst in the lamina quadrigemina.

[Deep brain stimulation in Parkinson's disease. Preliminary outcomes]. / Estimulación cerebral profunda en la enfermedad de Parkinson. Resultados preliminares.

BACKGROUND: Parkinson's disease justifies the use of deep brain stimulation (DBS) in certain patients who suffer from this condition. We present mid-term and long-term post-surgical outcomes in a cohort of 60 patients, who underwent DBS in the Hospital de Especialidades at Centro Médico Nacional Siglo XXI, in Mexico City. METHODS: Patients underwent conventional stereotactic surgery with FrameLink software (Medtronics Inc). This technique consisted in the presurgical evaluation, the placement of stereotactic frame, imaging studies, preoperative planning procedure, microrecording, macrostimulation, as well as the placement of electrodes and generators in two phases. The variables were included in a data platform for Excel management. It was also included a variety of measurement instruments for data comparison. As a standard measure, it was used the Unified Parkinson Disease Rating Scale (UPDRS) before the surgery and at 3, 12, and 36 months. RESULTS: 60 patients underwent surgery: 41 men and 19 women, with an average age of 56.5 years (39-70). There were good results in the majority of patients with preoperative UPDRS and at 3, 12 and 36 months of 79.57, 66.85, 65.29 and 58.75, respectively (p < 0.0001). There were complications in nine patients (15 %) and they were managed in a conservative manner. CONCLUSIONS: Postsurgical outcomes were from good to excellent in the majority of patients. Complications were minimal and conservatively managed. We propose the use of this procedure in a selected group of Parkinson's patients.

Introducción: la enfermedad de Parkinson puede justificar un procedimiento quirúrgico que consiste en la estimulación cerebral profunda. Se presentan resultados a mediano y largo plazo de una cohorte de 60 pacientes del Hospital de Especialidades del Centro Médico Nacional Siglo XXI. Métodos: los pacientes fueron operados con una metodología estereotáctica convencional a través del protocolo FrameLink (Medtronics Inc.). La técnica consistió en la evaluación preoperatoria de los pacientes, la colocación de marco estereotáctico, la realización de estudios de imagen, la planeación preoperatoria, el microrregistro, la macroestimulación y la colocación de implantes, que estuvo conformada por electrodos y generador en dos fases. La escala unificada para la evaluación de la enfermedad de Parkinson (UPDRS) preoperatoria, a tres, 12, y 36 meses fue utilizada como medida estándar. Se analizaron los resultados y las complicaciones como variables de interés. Resultados: se operaron 60 pacientes (41 hombres y 19 mujeres), con edad promedio de 56.5 años (rango de 39-70). Se obtuvieron de buenos a excelentes resultados en la mayoría de los pacientes con UPDRS promedio en periodo preoperatorio, a 3, 12 y 36 meses de 79.57, 66.85, 65.29 y 58.75, respectivamente (p < 0.0001). Las complicaciones se presentaron en forma mínima (en nueve pacientes: 15 %) y fueron manejadas de forma conservadora. Conclusiones: hubo una mejoría progresiva en el UPDRS durante los 36 meses de seguimiento.