Neurovascular Cases

What’s the diagnosis?

There is a homogenously enhancing right frontal tumor with vasogenic edema, mass effect and right-to-left midline shift. This tumor is the most likely cause of the patient’s first-ever seizure. The tumor is highly vascular and the right internal and bilateral external carotid arteries provide arterial inflow to the tumor.

Note the prominent flow voids, or vessels, along the periphery of the tumor

Distal right middle cerebral artery branches provide arterial inflow into the tumor. Note the vascular tumor blush that lasts late into the venous phase on these angiographic runs.

Middle meningeal and superficial temporal arteries provide arterial inflow into the tumor.

An hypertrophied left middle meningeal artery crosses over to the contralateral side to provide arterial inflow into the tumor.

Differential Diagnosis

  1. Meningioma
  2. Hemangiopericytoma

Background

  • Patients with large intracranial lesions that cause mass effect on the normal brain may benefit from steroids, which → ↓ vasogenic edema.
  • Patients with a newly identified brain tumor who have a seizure should be started on anti-epileptic medications to prevent further seizures.
  • Blood supply to extra-axial brain tumors typically arises from external carotid artery branches and from dural branches of the internal carotid arteries. However, highly vascular tumors can recruit substantial arterial inflow from the internal carotid artery and also from trans-osseous scalp arteries that travel through the bony skull to feed the tumor.

What's your treatment plan?

  • Large, symptomatic extra-axial brain tumors should be resected.
  • Preoperative, adjunctive endovascular embolization of highly vascular extra-axial brain tumors may devascularize the tumor before open surgery. Embolization may → ↓ intraoperative blood loss. Devascularizing the tumor may also improve the ease of microsurgical tumor resection.
  • Adjunctive endovascular embolization may → ↑ tumoral edema and ↑ mass effect in the short term. For this reason, the timing of microsurgical tumor resection is usually performed shortly after embolization.
  • There are many different embolic materials that can be used to sacrifice an artery. Microspheres are tiny porous beads suspended in contrast (so that they are visible when injected). Microspheres that are too small (i.e., <100 micrometers (μm)) → ↑ risk of embolization through tiny anastomoses and put cranial nerves at risk. Microspheres between 100-700 μm are more commonly used for tumor penetration.
  • It is important to be aware of potentially dangerous anastomoses, or connections, between the traditional internal and external carotid artery territories when performing an embolization. For example, a common anatomical variant includes an external carotid artery → middle meningeal artery → ophthalmic artery → central retinal artery. In such a case, embolizing the middle meningeal artery could put the patient’s vision at risk.
  • In addition to scrutinizing pre-embolization angiographic anatomy, neurological examinations should be performed before, during, and after the embolization to immediately identify any changes in vision or cranial neuropathy.

In this case, the patient underwent adjunctive endovascular embolization of right external carotid feeding arteries with microsphere particles and coils. The next day a right-sided craniotomy was performed with resection of the tumor and excision of the involved dura mater. Final tissue diagnosis was meningioma (World Health Organization Grade 1).

A microcatheter was advanced as distally as possible into the middle meningeal artery branches that were providing arterial inflow into the tumor. Microspheres were slowly injected until flow stagnation or any reflux along the microcatheter were noted.

Once the distal middle meningeal artery feeders were satisfactorily embolized, coils were used to embolize the more proximal middle meningeal artery trunk.