Ependymoma

Introduction

Ependymomas are relatively rare intracranial tumors that account for 1% to 5% of central nervous system tumors and arise from ependymal lining of the ventricular system or spinal canal. They account for 5% of central nervous system tumors in children and adolescents, but only 1.9% in adults. The overall 10-year survival rate for all patients with ependymomas is 79.2%; however, these tumors can occur anywhere along the neuroaxis, and therefore prognosis is different for different locations. Among ependymomas, a relatively common location is within the fourth ventricle, in which increasing extent of resection is associated with better overall and progression-free survival. ^, However, surgical morbidity remains relatively high and ranges from 10% to 30% in several series, in which the most significant morbidity is owing to injury of cranial nerve nuclei along the fourth ventricular floor. ^, In this chapter, we present a case of a patient with a fourth ventricular ependymoma.

Example case

Chief complaint: headaches, nausea, vomiting

History of present illness

A 38-year-old, right-handed woman with a history of asthma presented with headaches, nausea, and vomiting. Over the past 2 to 3 days, she complained of increasing bifrontal headaches that were recently accompanied by nausea and vomiting. She was seen by her primary care physician in which imaging revealed a brain lesion ( Fig. 77.1 ).

Medications : Albuterol inhaler.
Allergies : No known drug allergies.
Past medical and surgical history : Asthma.
Family history : No history of intracranial malignancies.
Social history : Engineer, no smoking, no alcohol.
Physical examination : Awake, alert, oriented to person, place, time; Cranial nerves II to XII intact; No drift, moves all extremities with good strength; No finger-to-nose dysmetria.
Spinal imaging : No evidence of drop metastases.

	William T. Couldwell, MD, PhD, University of Utah, Salt Lake City, UT, United States	Evandro de Oliveira, MD, PhD, Joao Paulo Almeida, MD, Institute of Neurological Sciences, São Paulo, SP, Brazil	James Rutka, MD, PhD, University of Toronto Sick Kids, Toronto, Canada	Reid C. Thompson, MD, Vanderbilt University, Nashville, TN, United States
Preoperative
Additional tests requested	Swallowing evaluation	Transesophageal echocardiogram Anesthesia evaluation	Neuroophthalmology evaluation Neuropsychological assessment Complete MRI brain and spine	Swallow evaluation
Surgical approach selected	Midline suboccipital craniotomy	Midline suboccipital craniotomy, C1 laminectomy	Midline suboccipital craniotomy	Midline suboccipital craniotomy, C1 laminectomy
Anatomic corridor	Telovelar	Telovelar	Telovelar	Telovelar
Goal of surgery	GTR	GTR, preservation of neurovascular structures	GTR	GTR, preservation of neurologic function
Perioperative
Positioning	Prone	Semisitting	Prone	Prone
Surgical equipment	Surgical navigation IOM (SSEP, MEP low cranial nerve EMG) Ultrasonic aspirator	Semisitting equipment Surgical navigation Precordial Doppler IOM (SSEP/MEP, EMG of cranial nerves V–XII) Brain retractors	Surgical microscope IOM Ultrasonic aspiratorBrain stimulator	Surgical microscope Weck vascular clips
Medications	Steroids Mannitol	Steroids	None	Steroids Mannitol
Anatomic considerations	Brainstem, PICA	Occipital bone and foramen magnum, posterior arch of C1, cerebellar hemisphere, tonsils, cerebellomedullary fissure, inferior medullary velum, tela choroidea, PICA, floor of fourth ventricle, upper spinal cord	Obex, floor of fourth ventricle, brainstem (medulla)	Medulla, lower cranial nerves, obex, PICA
Complications feared with approach chosen	Brainstem injury	Cerebellar/brainstem injury, floor of fourth ventricle damage, PICA stroke	Brainstem injury, cranial nerve injury (IX–XII), cerebellar injury	Brainstem injury, swallowing dysfunction, CSF leak, hydrocephalus
Intraoperative
Anesthesia	General	General	General	General
Skin incision	Linear	Linear from 2 cm above inion to C4	Linear	Linear from inion to C3
Bone opening	Midline suboccipital	Midline suboccipital and C1 laminectomy	Midline suboccipital +/– C1 laminectomy	Midline suboccipital and C1 laminectomy
Brain exposure	Cerebellar hemispheres, cervicomedullary junction	Cerebellar hemispheres, cervicomedullary junction	Cerebellar hemispheres, cervicomedullary junction	Cerebellar hemispheres, cervicomedullary junction
Method of resection	3 x 3 cm lower suboccipital craniotomy with foramen magnum, Y-shaped dural opening, drain CSF from cisterna magna, open tela choroidea at cerebellomedullary fissure, identify tumor and PICA, dissect tumor from roof of ventricle and PICA branches, avoid damage to brainstem floor, watertight dural closure with Alloderm	Semisitting position with precordial Doppler, expose fascia, Y-shaped muscle cuff above superior nuchal line, midline incision through avascular plane, muscle retraction, suboccipital craniotomy with removing lip of foramen magnum and C1 lamina, Y-shaped dural opening, drain CSF from cisterna magna, open tela choroidea at cerebellomedullary fissure, identify tumor and PICA, dissect tumor from roof of ventricle and PICA branches, attempted en bloc resection with preservation of ventricular floor, watertight dural closure with interposed muscle	Midline scalp incision from inion to C2, craniotomy of occipital bone +/– C1 laminectomy, Y-shaped dural opening, identify tumor below tonsils, dissect around tumor laterally, debulk with ultrasonic aspirator, identify floor of fourth ventricle and leave tumor if transgresses floor, remove tumor up to aqueduct, dural closure with graft, supplement with Tisseel	Midline incision, subperiosteal exposure of posterior fossa to foramen magnum and C1 lamina, keep musculature on C2 intact, posterior fossa craniotomy with inclusion of foramen magnum, drill laterally to widen exposure, palpate for vertebral arteries along C1 and laminectomy medially, Y-shaped dural opening to C1 with Weck vascular clips if circular venous sinus encountered, establish planes between tumor and brainstem with microscopic visualization, devascularize tumor capsule and internally debulk, mobilize tumor from cerebellar tonsils with protection of PICA, determine feasibility of removal if component stuck to brainstem, watertight dural closure with dural substitute
Complication avoidance	Dissect tumor from roof, preserve floor of fourth ventricle	Semisitting position, dissect tumor from roof, protect floor of fourth ventricle	Identify floor of fourth ventricle, do not transgress floor, dissect around lateral edges	Identify floor of fourth ventricle, intraoperative decision to remove completely based on adherence to the brainstem and plane of separation
Postoperative
Admission	ICU	ICU	ICU	ICU, keep intubated over night
Postoperative complications feared	Brainstem injury, swallowing dysfunction	Hydrocephalus, injury to floor of fourth ventricle (lower cranial nerve deficits, motor/sensory deficits, decreased consciousness)	CSF leak, hydrocephalus, brainstem injury, cranial nerve nuclei injury	Brainstem injury, swallowing dysfunction, CSF leak, hydrocephalus
Follow-up testing	MRI within 24 hours after surgery	MRI within 24 hours after surgery	MRI within 24 hours after surgery	MRI night of surgery Complete spine MRI Swallowing evaluation 1 day after surgery
Follow-up visits	1 month after surgery	15 days after surgery 6 months after surgery	4–6 weeks after surgery	14 days after surgery 6 weeks after surgery
Adjuvant therapies recommended	GTR–radiation STR–radiation	GTR–observation STR–reoperation, radiation if repeat surgery does not achieve GTR Grade III–radiation	GTR–observation vs. focal radiation therapy STR–possible repeat surgery if possible or radiation therapy	GTR–radiation therapy STR–possible repeat surgery if possible or radiation therapy