Osteological studies of skull base neurovascular area in reference to infratemporal approach to skull basec

Surgical approaches to the lateral skull base often lead to tearing of vessels and piecemeal removal of the tumour. This study is aimed to delineate exact relationship of the various foramina at the lateral skull base. The coronal dimensions of the jugular foramina are larger as compared to sagittal with right sided dominance also noticed in the case of carotid canal. The width of “Keel” separating the carotid and jugular foramina normally varies from 0.4 to1.4 centimetres and may not always suggest the erosion of the foramen of skull base scans, unless the erosion is associated with irregularity or demineralization the thickness of this keel really depends upon relative size of the vessels and location of foramina. Area between stylomastoid foramen, carotid canal and jugular foramen is roughly wedge shaped. The angle subtended by carotid and jugular at the stylomastoid foramen is about 36.84whereas the location of stylomastoid foramen and internal carotid axis pose an angle of 83:16. The angle subtended by stylomastoid and jugular at carotid on an average 59:31. The space between these structures is measured to be 0.642centimetres which can be verified on tomograms. By using these measurements, the precise location of the upper end of the vessels could be predicted, whereas the superior stump could be clamped with minimal exposure of the skull base and identification and location of the last four cranial nerves is found out. This could avoid injuries and subsequent morbidity while carrying out surgery in this region.

Repair of a large primary subtemporal encephalocele in a 3-year-old child: case report

Primary encephaloceles (PEs) present only rarely in the temporal region; in the rare instance that they project through the floor of the middle fossa they are secondary. In this case report the authors report on the management of a giant PE extending through the floor of the middle fossa.An 8-month-old boy presented to the authors’ service with a large PE projecting into his neck through a missing left middle fossa floor; the lesion was causing significant meta-, dys-, and hypoplasia of the structures of the anterolateral neck on that side. Surgical goals for this patient included the following: 1) removal of potentially epileptogenic and dysfunctional tissue; 2) preservation of cranial nerves; 3) prevention of cognitive decline or iatrogenic deficit; 4) prevention of CSF leak; 5) reconstruction of skull base; 6) prevention of airway and swallowing compromise; and 7) cosmesis. After a multidisciplinary evaluation with ENT, plastic surgery, and neurology, an operation was performed using a preauricular infratemporal approach when the patient was 3 years old. Gliotic tissue was resected and amygdala, hippocampus, and middle cerebral artery were preserved.The immediate results of the operation showed good immediate outcome. Seizure freedom and neurodevelopment outcomes remain to be seen at follow-up.

Microsurgical and Endoscopic Anatomy of the Extended Retrosigmoid Inframeatal Infratemporal Approach

BACKGROUNDDifferent and often complex routes are available to deal with jugular foramen tumors with extracranial extension.OBJECTIVETo describe a novel extension of the retrosigmoid approach useful to expose the extracranial area abutting the posterior fossa skull base.METHODSA navigation-guided, endoscope-assisted retrosigmoid inframeatal approach was performed on 6 cadaveric heads in the semisitting position, displaying an area from the internal acoustic meatus to the lower cranial nerves and exposing the intrapetrous internal carotid artery. We then continued removing the temporal bone located between the sigmoid sinus and the hearing apparatus, reaching the infratemporal area just lateral to the jugular fossa. This drilling, which we refer to as posterolateral inframeatal drilling, has not previously been described. Drilling of the horizontal segment of the occipital squama allowed good visualization of the uppermost cervical internal carotid artery, internal jugular vein, and lower extracranial cranial nerves.RESULTSWe were able to provide excellent exposure of the inframeatal area and of the posterior infratemporal fossa from different operative angles, preserving the neurovascular structures and the labyrinth in all specimens. The intradural operative window on the extracranial compartment was limited by the venous sinuses and the hearing apparatus and presented a mean width of 8.52 mm. Sigmoid sinus transection led to better visualization of the lateral half of the jugular foramen and of the uppermost cervical internal carotid artery.CONCLUSIONThe navigation-guided endoscope-assisted extended retrosigmoid inframeatal infratemporal approach provides an efficient and versatile route for resection of jugular foramen tumors with extracranial extension.