Cisternotomy and fenestration of Liliequist’s membrane as surgical treatment of idiopathic intracranial hypertension (pseudotumor cerebri): a case report

Cisternotomy and fenestration of Liliequist’s membrane as surgical treatment of idiopathic intracranial hypertension (pseudotumor cerebri): a case report

Opening the basal subarachnoid cistern (cisternotomy) is used during many microsurgical operations to relax the brain by withdrawing or diverting cerebrospinal fluid (CSF). Recently, cisternotomy has been used in patients with traumatic brain injury to improve outcomes due to its ability to decrease intracranial pressure (ICP) and cerebral edema by diverting CSF. Theoretically, another condition that may benefit from cisternotomy is idiopathic intracranial hypertension (IIH), as it presents with manifestations of increased ICP, such as headache, vomiting, and papilledema. Here, we discuss the case of a 39-year-old woman with IIH who presented with headache, nausea, and papilledema in the setting of maximally tolerated medical therapy after five months of shunt removal due to infection. The patient did not want to proceed with the replacement of her derivation, so a right eyebrow craniotomy was performed for cisternotomy, fenestration of the terminal laminae and opening of Liliequist’s membrane. After the operation, her symptoms completely improved. She was completely off acetazolamide at the three-month follow-up and no longer had pseudotumor cerebri headaches. This case report demonstrates the use of cisternotomy to relieve manifestations of increased ICP and its potential as a surgical option for patients with IIH.

Introduction

Idiopathic intracranial hypertension (IIH) presents with manifestations of increased intracranial pressure (ICP), such as headache, pulsatile tinnitus, diplopia, vomiting, and papilledema. [1]. Neuroimaging is required to diagnose IIH to exclude other causes of increased ICP, such as tumors. On magnetic resonance imaging (MRI), patients with IIH have normal brain parenchyma and ventricles without hydrocephalus, mass lesions, or abnormal meningeal enhancement. [1,2]. Elevated lumbar puncture opening pressure and relief of symptoms after lumbar puncture with normal cerebrospinal fluid (CSF) composition are hallmarks of pseudotumor cerebri [1,2].

Traditional treatment for IIH patients includes weight loss and carbonic anhydrase inhibitors [3,4]. Surgical treatment of cases refractory to medical treatment involves the placement of a CSF shunt [5,6]. In theory, another potential treatment for IIH is opening of the subarachnoid basal cistern (cisternotomy). Cisternotomy is used during many microsurgical operations to relax the brain by removing or diverting cerebrospinal fluid. [7]. Recent developments indicate that CSF from the ventricles does not communicate with the parenchyma, rather CSF from the cisterns communicates with the parenchyma through the Virchow-Robin spaces via the glymphatic system. [8,9]. Based on this, it is assumed that the release of CSF through a cisternotomy increases the elimination of interstitial fluid and CSF. A review of the literature did not reveal any similar cases. This case is considered the first reported case of IIH treated with cisternotomy.

case presentation

A 39-year-old woman presented with headaches and nausea and was diagnosed with IIH on maximally tolerated medical therapy. She had no other comorbidities. Her physical examination was normal except for grade 1 papilledema. During hospitalization, imaging studies showed normal brain parenchyma and ventricles with no hydrocephalus or mass lesions on MRI (Figure 1). Furthermore, MRI or MRI venography did not show sinus venosus stenosis. The patient’s symptoms were greatly improved with a lumbar drainage test; therefore, a ventriculoperitoneal shunt was placed.

Unfortunately, five months later, the patient’s shunt had to be completely removed due to infection and acetazolamide was restarted. One month later, he had three weeks of progressive headaches and nausea. Headaches improved after a large volume lumbar puncture showing an opening pressure of 27 cmHtwoO. CSF analyzes were normal. The patient refused replacement of her shunt as the next step in management and underwent a craniotomy of the right eyebrow for cisternotomy, fenestration of the laminae terminals, and opening of Liliequist’s membrane (Figure two).

During surgery, the arachnoid was found to be exceptionally thick and required almost exclusive sharp dissection (Figure two). There were no postoperative complications and the patient experienced complete resolution of her symptoms. She was completely off acetazolamide at the three-month follow-up and she no longer had IIH headaches. Postoperative magnetic resonance imaging showed normal brain parenchyma and ventricles without hydrocephalus or mass lesions (Figure 3). The neuro-ophthalmology visit showed stable grade 1 papilledema.

Discussion

During many microsurgical operations, cisternotomy is used to relax the brain by diverting CSF. Recent developments indicate that CSF from the cisternae communicates with the brain parenchyma through the Virchow-Robin spaces via the glymphatic system. [8,9]. Allowing drainage of CSF through the cisterns by surgically opening them to atmospheric pressure may encourage drainage of CSF and interstitial fluid through the Virchow-Robin spaces, subsequently reducing ICP. [10]. Many previous clinical studies have shown that cisternotomy with decompressive craniotomy (DC) is associated with better outcomes compared to DC alone in patients with traumatic brain injury. [10,11].

In theory, other causes of increased ICP, such as IIH, may benefit from cisternotomy. In our case report, the patient’s symptoms improved after cisternotomy with opening of the Liliequist membrane and fenestration of the lamina terminalis in the postoperative period and at the three-month follow-up.

Conclusions

Cisternotomy is a safe microsurgical procedure that can effectively lower ICP and relax the brain. We present a case of IIH treated with cisternotomy, opening of Liliequist’s membrane and fenestration of the terminal lamina. This effect can be explained by the recently discovered glymphatic system. Cisternotomy with fenestration of the lamina terminalis and opening of the Liliequist membrane presents a potential novel surgical option for patients with IIH. Larger multicentre randomized trials are needed to establish the effectiveness of cisternotomy in the treatment of IIH.

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