Cerebellopontine angle meningioma

Introduction

Cerebellopontine angle (CPA) meningiomas account only for ~1% of meningiomas; however, among posterior fossa meningiomas; they account for 50% to 60% of these lesions. Lesions in this region are typically slow-growing and reach large sizes before presenting with symptoms that include hearing loss/tinnitus, ataxia, headache, facial pain, facial numbness, and/or swallowing difficulties, among others. Surgery in this region is associated with morbidity rates that range from 40% to 60% in several series, with subtotal resection rates of 15% to 60%. As a result of these surgical risks, radiation therapy has also been offered not only postoperatively but also upfront for these lesions. In this chapter, we present a case of a patient with a left CPA meningioma.

Example case

Chief complaint: left facial twitching and weakness

History of present illness

A 57-year-old, right-handed woman with known left CPA lesion presented with increased left facial twitching and weakness. She was diagnosed with this lesion approximately 10 years prior during workup for headaches. This was followed with serial imaging without significant change in tumor size ( Fig. 51.1 ). However, she developed progressive left facial twitching and weakness over the past 2 to 3 months.

Medications : None.
Allergies : No known drug allergies.
Past medical and surgical history : Meningioma, right knee surgery.
Family history : No history of intracranial malignancies.
Social history : Nurse, no smoking, occasional alcohol.
Physical examination : Awake, alert, oriented to person, place, and time; Cranial nerves II to XII intact (including intact hearing) except left House-Brackmann 2/6; No drift, moves all extremities with full strength; Cerebellar: no finger-to-nose dysmetria.

	Gordon Li, MD, Stanford University, Palo Alto, CA, United States	Hirofumi Nakatomi, MD, PhD, University of Tokyo, Tokyo, Japan	Vicent Quilis-Quesada, MD, PhD, University of Valencia, Valencia, Spain	Jamie J. Van Gompel, MD, Mayo Clinic, Rochester, MN, United States
Preoperative
Additional tests requested	Audiogram	Audiogram (PTA, SDS) BAERs/MR for facial spasm ENT evaluation (facial function, swallowing, phonics) Cerebral angiogram	CT angiogram CT	Audiogram
Surgical approach selected	Left retrosigmoid craniotomy	Left retrosigmoid craniotomy with IAC opening	Left retrosigmoid craniotomy, IAC opening, suprameatal petrosectomy	Left retrosigmoid craniotomy, suprameatal petrosectomy
Anatomic corridor	Left retrosigmoid	Left retrosigmoid	Left retrosigmoid	Left retrosigmoid
Goal of surgery	Extensive resection, decompress brainstem, avoid cranial nerve injury, Simpson grade III	Simpson grade II, with preservation of cranial nerves	Simpson grade I	Extensive resection without neurological compromise, decompress brainstem, Simpson grade III
Perioperative
Positioning	Left supine with right rotation	Left lateral	Left park bench	Left lateral decubitus
Surgical equipment	Surgical navigation IOM (MEP, SSEP, cranial nerves) Surgical microscope Brain retractor Ultrasonic aspirator	Surgical navigation IOM (MEP, facial EMG, BAERs) Surgical microscope Ultrasonic aspirator Weck/AVM clips Microanastamosis set	IOM (MEP, SSEP, BAERs, cranial nerves V, VII–XII) Surgical microscope Ultrasonic aspirator	IOM (BAERs, cranial nerves V and VII) Surgical microscope
Medications	Steroids	Mannitol Steroids	None	Steroids
Anatomic considerations	Brainstem, cranial nerves V–XI	Cranial nerves V–XI	Sigmoid sinus, AICA, cranial nerves IV–V/VII–XII, SCA, superior petrosal vein, brainstem	Cranial nerves V, VII, and VIII
Complications feared with approach chosen	Cranial nerves, brainstem, cerebellum, sigmoid/transverse sinus injury, CSF leak	Hearing decline and facial palsy	Cranial neuropathy, vascular injury	Hearing loss, facial weakness, facial numbness
Intraoperative
Anesthesia	General	General	General	General
Skin incision	Retrosigmoid linear	Retrosigmoid lazy S	Retroauricular U-shaped	Retrosigmoid curvilinear
Bone opening	Suboccipital up to transverse sinus, lateral to sigmoid, and inferior to foramen magnum	Suboccipital, retrosigmoid with exposure of transverse-sigmoid sinuses, removal of foramen magnum and condylar drilling	Suboccipital, retrosigmoid with exposure of transverse-sigmoid sinuses	Suboccipital, retrosigmoid
Brain exposure	Cerebellum and CPA	Cerebellum and CPA	Cerebellum and CPA	Cerebellum and CPA
Method of resection	Retrosigmoid linear incision that is one-third above and two-thirds below transverse sinus extending to foramen magnum, burr hole at transverse/sigmoid sinus, suboccipital craniotomy down to foramen, dural opening, open cisterna magna and release CSF, brain retractor to move cerebellum away, identify tentorium and tumor, stimulate tumor to confirm nondorsal location of facial nerve, cut window into tumor and debulk with ultrasonic aspirator, once enough debulking find trigeminal nerve superiorly and lower cranial nerves inferiorly, continue to stimulate and debulk, peel tumor off of brainstem gently, attempt gross total resection, unless stuck to cranial nerves VII or VIII or brainstem, close dura with dural graft if necessary, cover bone defect with bone cement	Suboccipital craniotomy with foramen magnum opening and condylar drilling, Y-shaped dural opening, continuous epidural suction, dissect lateral cerebellomedullary fissure to identify foramen of Luschka and paratrigeminal cistern, electrodes to monitor cranial nerves VII and VIII, devascularize tumor from petrotentorial angle (often meningohypophyseal trunk/tentorial/ascending pharyngeal artery), debulk tumor in four quadrant division to identify cranial nerves, dissect from brainstem after enough debulking, open IAC with attention to the posterior semicircular canal and endolymphatic sac, remove IAC tumor component with curettes, secure IAC air cells with muscle and glue, dural closure, subgaleal drain insertion	Layer by layer dissection to facilitate closure, suboccipital craniotomy with exposure of transverse and sigmoid sinuses, dural opening, open cisterna magna for cerebellar relaxation, CPA and tumor exposure, tumor debulking, subarachnoid dissection, cranial nerve and vessel exposure and preservation, IAC drilling and tumor resection, suprameatal approach, tumor resection, dural removal and bone drilling, inferior part of the tumor resection from lower cranial nerves, watertight dural closure with dural graft if necessary	Suboccipital retrosigmoid craniotomy, dural opening, identify and stimulate for cranial nerves, remove as much tumor between cranial nerves as possible with ultrasonic aspirator or bipolar cautery, drill out suprameatal bone superior to the IAC to the Meckel cave to expose superior portion of tumor, remove more tumor, watertight dural closure
Complication avoidance	Decompress cisterna magna, identify superior and inferior poles, stimulate for CN VII, leave residual if adherent	Large bone opening with foramen magnum and condylar fossa, electrodes to monitor cranial nerves VII and VIII, debulking of tumor before dissecting	Large bone opening, decompress cisterna magna, debulk tumor, drilling out IAC and suprameatal approach, leave inferior tumor for last	Large bone opening, work in-between cranial nerves, suprameatal bone drilling
Postoperative
Admission	ICU	ICU	ICU	Intermediate care
Postoperative complications feared	Cranial nerve injury, CSF leak, brainstem stroke	Hearing loss, facial palsy, facial dysesthesias	Facial nerve injury, lower cranial neuropathy, vascular complications, CSF leak	Hearing loss, facial weakness, facial numbness, stroke
Follow-up testing	MRI 3–6 months after surgery	MRI/MRA/MRV within 72 hours after surgery	MRI within 48 hours after surgery	MRI within 3 months after surgery
Follow-up visits	10 days after surgery	1 month after surgery	4–6 weeks after surgery	3 months after surgery
Adjuvant therapies recommended for WHO grade	Grade I–observation Grade II–radiation Grade III–radiation	Grade I–observation Grade II–SRS Grade III–radiation	Grade I–observation Grade II–observation Grade III–observation	Grade I–observation Grade II–radiation Grade III–radiation