Dural arteriovenous fistula following translabyrinthine resection of cerebellopontine angle tumors: report of two cases

Iatrogenic intracranial venous hypertension treated with intracranial venous stenting: illustrative case

BACKGROUND

Venous sinus injury resulting in thrombosis is a possible complication of skull base surgery and neck dissection. Although usually asymptomatic, sinus thrombosis can obstruct the dominant cranial venous outflow pathways, leading to a cycle of increased intracranial pressure secondary to venous congestion, which further compresses the remaining sinuses in a positive feedback loop. This can present with symptoms resembling idiopathic intracranial hypertension.

OBSERVATIONS

A patient underwent a left mastoidectomy for chronic mastoiditis, complicated by injury of the ipsilateral dominant sigmoid sinus, with subsequent thrombosis. The patient developed chronic severe headaches, papilledema, visual blurring, and tinnitus. Angiography revealed a contralateral arachnoid granulation causing stenosis of the remaining venous outflow tract with a pressure gradient of 18 mm Hg. Transverse sinus stenting led to normalization of the gradient and resolution of symptoms.

LESSONS

Injury of a dominant cranial venous outflow pathway led to a feedback loop that caused increased intracranial pressures and worsening contralateral transverse sinus stenosis, which was successfully treated using transverse sinus stenting. Venous congestive physiology leading to intracranial hypertension is underrecognized as a complication of venous injury in skull base surgery and responds to stenting if the patient's symptoms are refractory to conservative management or anticoagulation. https://thejns.org/doi/10.3171/CASE24781.

Acquired progressive torcular dural arteriovenous fistula after subtotal resection of peritorcular meningioma

A woman in her mid-50s who had undergone a subtotal resection of a peritorcular meningioma 3 years earlier presented with symptoms suggestive of increased intracranial pressure. A delayed diagnosis of a torcular dural arteriovenous fistula (dAVF) diagnosis was made on MRI. Digital subtraction angiography confirmed a torcular dAVF (Borden type II). Staged 3 rounds of transarterial (TA) embolisation were performed using n-butyl cyanoacrylate, ethylene vinyl alcohol copolymer and coils of the complex torcular dAVF, which significantly reduced the flow and corresponded with improved symptoms of pulsatile tinnitus, vision and headache. We reviewed previously reported cases of dAVFs that developed after craniotomy for meningioma resection. Despite its rarity, a torcular dAVF can develop after craniotomy and progress from low to high grade due to its location. Diagnosis requires a thorough understanding of subtle imaging findings, which may be present in follow-up studies obtained for tumour surveillance.

Functional Outcomes and Postoperative Cerebral Venous Sinus Thrombosis after Translabyrinthine Approach for Vestibular Schwannoma Resection: A Radiographic Demonstration of Anatomic Predictors

Introduction While regarded as an effective surgical approach to vestibular schwannoma (VS) resection, the translabyrinthine (TL) approach is not without complications. It has been postulated that postoperative cerebral venous sinus thrombosis (pCVST) may occur as a result of injury and manipulation during surgery. Our objective was to identify radiologic, surgical, and patient-specific risk factors that may be associated with pCVST.

Methods The Institutional Review Board (IRB) approval was obtained and the medical records of adult patients with VS who underwent TL craniectomy at University Hospitals Cleveland Medical Center between 2009 and 2019 were reviewed. Demographic data, radiographic measurements, and tumor characteristics were collected. Outcomes assessed included pCVST and the modified Rankin score (mRS).

Results Sixty-one patients ultimately met inclusion criteria for the study. Ten patients demonstrated radiographic evidence of thrombus. Patients who developed pCVST demonstrated shorter internal auditory canal (IAC) to sinus distance (mean: 22.5 vs. 25.0 mm, p = 0.044) and significantly smaller petrous angles (mean: 26.3 vs. 32.7 degrees, p = 0.0045). Patients with good mRS scores (<3) appeared also to have higher mean petrous angles (32.5 vs. 26.8, p = 0.016). Koos' grading and tumor size, in our study, were not associated with thrombosis.

Conclusion More acute petrous angle and shorter IAC to sinus distance are objective anatomic variables associated with pCVST in TL surgical approaches.

Venous sinus compromise after pre-sigmoid, transpetrosal approach for skull base tumors: A study on the asymptomatic incidence and report of a rare dural arteriovenous fistula as symptomatic manifestation

The sigmoid sinus is routinely exposed and manipulated during pre-sigmoid, transpetrosal approaches to the skull base, but there is scant data available on the incidence of venous sinus compromise after surgery. We encountered a dural arteriovenous fistula as a result of sigmoid sinus occlusion and examined the incidence of venous sinus thrombosis or narrowing after transpetrosal surgeries. We performed a retrospective analysis of a series of patients treated by the senior surgeons (WCJ, MH, HJK), who underwent either a posterior petrosectomy or translabyrinthine approach for various skull base tumors. All available clinical and radiographic data were thoroughly examined in each patient to determine the post-operative fate of the venous sinuses. Of the 52 available patients, five patients were discovered post-operatively to have a narrowed or constricted sigmoid sinus ipsilateral to the surgery, whereas another five patients were diagnosed with asymptomatic sinus thrombosis either in the transverse or sigmoid or both. None of these patients experienced symptoms, nor were there any instance of ischemic or hemorrhagic complications. However, there was one additional patient who presented with pulsatile tinnitus 2years after surgery. His angiogram showed an occlusion of the ipsilateral sigmoid sinus and a posterior fossa dural arteriovenous fistula. A two-stage transvenous and transarterial embolization was successful in eliminating the fistula. Technical considerations to avoid sinus injuries during pre-sigmoid, transpetrosal surgery are discussed.