Does a Tectal Glioma Need Cancer Treatment or Fluid Bypass?

Hearing that a brain tumor like a tectal glioma is causing your blocked spinal fluid is terrifying. It is completely normal to wonder when traditional cancer treatments will begin. However, in many cases, a tectal glioma does not require immediate treatments like chemotherapy, radiation, or tumor removal surgery ^[1][2].

Instead, the immediate focus is usually on relieving the dangerous pressure in your brain by bypassing the blocked fluid ^[3][1]. Once the fluid is flowing properly, a typical tectal glioma is often managed with “active surveillance”—closely monitoring the tumor with regular MRIs to see if it grows ^[1][2]. However, the exact plan depends heavily on your specific MRI pattern, age, symptoms, and whether the tumor shows signs of progression over time.

Understanding Tectal Gliomas

The tectum is the roof of the brainstem, located right next to the aqueduct of Sylvius (the narrow channel where cerebrospinal fluid flows). A tectal glioma is a tumor that grows in this area.

While the word “tumor” or “glioma” sounds alarming, many tectal gliomas appear to be low-grade and very slow-growing (indolent) on imaging ^[1][2]. Because the aqueduct is so narrow, even a tiny, slow-growing tumor can compress it and block the flow of fluid, causing a backup called hydrocephalus ^[3]. The symptoms you are experiencing—such as severe headaches, nausea, or vision changes—are often related to this fluid buildup and pressure ^[3]. However, symptoms can sometimes reflect direct brainstem involvement, so they always require careful clinical assessment by your medical team.

Treating the Fluid First

Because the most immediate danger comes from the fluid buildup, the first step in treatment is usually a procedure to divert the cerebrospinal fluid around the blockage ^[3][4]. Attempting to surgically remove the entire tumor is rarely the first step, because operating on the brainstem carries significant risks and is usually unnecessary to fix the fluid blockage ^[5][6].

Fluid diversion is typically done through one of two procedures:

• Endoscopic Third Ventriculostomy (ETV): A surgery that creates a new bypass pathway for the fluid to flow out of the brain, bypassing the blocked aqueduct entirely ^[3][1].
• Ventriculoperitoneal (VP) Shunt: A tube placed in the brain to drain the excess fluid into the abdomen ^[3][4].

The choice between an ETV and a shunt is highly individualized based on your anatomy and clinical condition. Both procedures treat the hydrocephalus, not the tumor, and both require their own monitoring. An ETV can sometimes close or fail, and a shunt can become blocked, infected, or over-drain.

⚠️ When to Seek Emergency Care

Whether you are waiting for a procedure or recovering from an ETV or shunt, uncontrolled hydrocephalus is a medical emergency. Do not wait for your next scheduled appointment or MRI. Seek emergency care immediately if you or your loved one experience:

• Rapidly worsening or severe headache
• Repeated vomiting
• Increasing sleepiness, confusion, or difficulty waking up
• Fainting or seizures
• New weakness or trouble walking
• Sudden or worsening vision changes (like double vision or trouble looking up)
• For shunt patients: fever, or redness/drainage along the surgical incision

Active Surveillance

After the hydrocephalus is treated, many patients with typical tectal gliomas enter a phase of active surveillance (watchful waiting) ^[1][2].

This means your medical team will monitor you closely with regular MRI scans and neurological exams. The schedule is individualized; MRIs may be frequent at first, then spaced out if the tumor remains stable. Studies following both pediatric and adult patients over roughly 10-year periods show that a majority of typical tectal gliomas remain stable ^[7][8]. However, in these studies, roughly 20% to 25% of patients eventually showed radiographic progression (growth on an MRI) or required tumor-directed treatment ^[7][9][8].

When is the Plan Reassessed?

Watchful waiting is not simply ignoring the tumor. Your multidisciplinary team (neurosurgeons and neuro-oncologists) will continually reassess the plan. They may consider a biopsy, surgery, chemotherapy, or radiation if:

• The tumor shows clear, continuous growth on successive MRI scans ^[7][10].
• The tumor extends outside the tectum or further into the brainstem ^[7].
• You develop progressive neurological deficits that are caused by the tumor itself, despite the hydrocephalus being well-controlled ^[7][5].
• The MRI shows atypical features, such as new contrast enhancement (areas that light up brightly from the MRI dye). Enhancement alone does not guarantee the tumor is aggressive, but it is a feature doctors watch closely ^[7][1].
• A biopsy is taken (sometimes during the ETV) because the imaging looked unusual, and it reveals a different, more aggressive diagnosis entirely (such as a lymphoma), which requires separate, specific treatments ^[11][12].

Living with a brain tumor that isn’t being removed can cause profound anxiety. It is important to remember that by managing the fluid and monitoring the tumor closely, your medical team is balancing the control of hydrocephalus with avoiding unnecessary, risky treatments, based specifically on your findings.