Intracranial hypertension following sacrifice of occipital and marginal sinuses during posterior fossa decompression for Chiari I malformation: case report

Occipital Sinus-Sparing Linear Paramedian Dural Incision: A Technical Note and Case Series for Median Suboccipital Approach

BACKGROUND

Durotomies, traditionally used during the midline suboccipital approach, involve sacrificing the occipital sinus (OS) with consequent shrinking of the dura, risk of venous complications, difficulty performing watertight closure, and a higher rate of postoperative cerebrospinal fluid (CSF) leaks. The present technical note describes the OS-sparing linear paramedian dural incision, which leads to a decrease in the risk of complications during the median suboccipital approach in our case series.

METHODS

The OS-sparing linear incision technique involves a dural incision placed 1 cm lateral to the OS. The angle of view of the microscope is frequently changed to overcome the narrowed exposure of the linear durotomy. Copious irrigation with saline prevents drying of the dura. A running watertight closure of the dura is performed. The overall results of 5 cases are reviewed.

RESULTS

The cases were 3 tumors and 2 cavernomas. The OS was preserved in all 5, and no duraplasty was needed. The average dura closure time was 16.8 minutes. No CSF leak occurred, and no wound complications were observed. A gross total resection of the lesion was achieved in all the patients. The mean follow-up was 10.2 months, and there were no late complications related to the dura closure.

CONCLUSIONS

In comparison to the types of durotomies conventionally used for the midline suboccipital approach, the OS-sparing linear paramedian dural incision entails lower risks of bleeding, venous complications, CSF leaks, and infections by avoiding duraplasty. Validation of this technical note on a larger patient cohort is needed.

Median trans-atlanto-occipital membrane microsurgical approach to the posterior cranial fossa without craniotomy

Minimally invasive approaches are becoming increasingly popular and contributing to improving the results of the surgical treatment of a wide variety of intracranial pathologies. Fifteen patients with posterior cranial fossa tumors underwent microsurgery through the atlanto-occipital membrane without resection of any bone structures. Tumors were localized in the brainstem in 8 patients and in the fourth ventricle in 7 patients. According to preoperative MRI and CT scans, the distance between the posterior arch of the atlas and the opisthion ranged from 9.9 to 16.5 mm (median 13 mm). The surgery was performed with the patient in the prone position and the head flexed. The trajectory of the surgical approach was directed from the skin incision located above the C2 spinous process 3.5-4 cm rostral along the midline. Total tumor resection was performed in 10 patients, subtotal resection in 2 patients, partial resection in 1 patient, and open biopsy in 2 patients. Surgical complications occurred in only 1 patient (meningoencephalitis). This minimally invasive trans-atlanto-occipital membrane approach for posterior cranial fossa tumors provides adequate visualization of the caudal part of the fourth ventricle and brainstem when the anthropometric parameters of the patient are suitable.

Management of a Persistent Oblique Occipital Sinus with Staged Ligation in a Case of Medulloblastoma: A Case Report

INTRODUCTION

A patent persistent occipital sinus (OS) can be seen in 10% of adults. The presence of such a dominant draining OS can present as a challenge for posterior fossa surgeries. Occlusion or division of the sinus can cause venous hypertension, causing a cerebellar bulge or increased intra-op bleeding.

CASE REPORT

A 3-and-a-half-year-old female child presented with a vermian medulloblastoma with hydrocephalus. MR venography (MRV) revealed a large patent OS draining from the torcula to the right sigmoid sinus. She underwent a left Frazier's point VP shunt followed by a midline suboccipital craniotomy for the lesion. The OS was divided during a "Y"-shaped durotomy. Following the sinus ligation, there was a significant cerebellar bulge and excessive bleeding from the lesion. We released cisternal CSF and punctured the tumor cysts to allow the brain bulge to settle. Hemostasis was secured, and surgery was deferred, an augmented duroplasty was done, and bone flap was removed to allow for intracranial pressure decompression. The patient was electively ventilated for 24 h and weaned off gradually. A repeat MRV at 7 days showed the reorganization of the venous outflow at the torcula. Reexploration with tumor resection was done on post-op day 10. The patient recovered well from the surgery and was referred for adjuvant therapy.

CONCLUSION

Surgeons should carefully analyze venous anatomy before posterior fossa surgeries. The persistent dominant OS, when present, should be taken care of while planning the durotomy. A hypoplastic but persistent transverse sinus allowed us to ligate and divide the OS. By doing a staged division of the sinus, reorganization of the venous outflow from the torcula can be allowed to occur, and the lesion can be resected.