Radiological Category:
Neuroradiology
Principal Modality (1): MRI
Principal Modality (2): CT
Case Report: Cerebellopontine Angle Tumor
Submitted by:
Grant Holz, MS4
Faculty reviewer: Sandra Oldham, MD
Date: 9/28/11
Case History
•
65 yo female with PMH of a left-sided cerebellopontine angle tumor resected in
1999 presented with a 2 week history of headache, dizziness, and N/V. She
went to an outside hospital where a CT scan showed a new left-sided
cerebellopontine angle mass, and she was transferred to Memorial Hermann
Hospital. She was admitted to the neurosurgery ICU and IV steroids were
started. An MRI was obtained which showed a large enhancing heterogeneous
mass, measuring 4.6 x 4.4 x 4.0 cm situated in the left cerebellopontine angle.
The patient remained at GCS 15 with no clinical signs of hydrocephalus. Her
neuro exam demonstrated left-sided weakness and left facial palsy that were
secondary to her left posterior craniotomy in 1999, and have been stable since.
Due to the large complexity of the tumor, it was decided to conservatively
manage the patient on an outpatient basis, in order to explore surgical options.
T1 Axial Pre-Contrast
T2 Axial Pre-Contrast
Enlarged Lateral Ventricles
T1 Axial Post-Contrast
Slice # 1
(Superior margin
of tumor)
T1 Axial Post-Contrast
Slice #2
T1 Axial Post-Contrast
Slice #3
T1 Axial Post-Contrast
Slice #4
T1 Axial Post-Contrast
Slice #5
T1 Axial Post-Contrast
Slice #6
T1 Axial Post-Contrast
Slice #7
(Inferior margin
of tumor)
T1 Coronal Post-Contrast
Stealth Axial – Jugular Vein Effacement
Stealth Axial – Decreased Caliber of L Jugular Vein
CT Head with Soft Tissue Window
CT Head – Bone Window
Background
Cerebellopontine angle anatomy
- Located in posterior fossa
Bounded by:
brainstem medially
petrous portion of temporal bone laterally
middle cerebellar peduncle superiorly
arachnoid tissue of lower CN inferiorly
-
-
Symptoms of Cerebellopontine angle masses
- Sensory hearing loss
- Disequilibrium or vertigo
- Hemifacial weakness or paralysis
- Decrease in sensation of the external auditory canal
- Wide based gait
- Headaches and visual loss
Study of choice = MRI w contrast
Test Your Diagnosis
Which one of the following is your choice for the appropriate diagnosis?
• Vestibular schwannoma / Acoustic neuroma
• Meningioma
• Epidermoid tumor
Findings:
Enhancing heterogeneous mass in the L CPA measuring 4.6 x 4.4 x 4 cm w
multiple areas of cystic degeneration and hemorrhage. An intracanalicular
component is noted with widening of the L internal auditory canal. Marked mass
effect upon the adjacent brainstem and cerebellum w stretching and thinning of the
L middle cerebellar peduncle and edema in the L cerebellar hemisphere. The 4th
ventricle is effaced and there is mild supratentorial hydrocephalus with
transependymal CSF flow. The mass extends into the L jugular foramen. The L
jugular vein is completely effaced in the foramen and is decreased in caliber just
below the skull base with filling via collaterals and the inferior petrosal sinus. The
mass also extends inferiorly to the foramen magnum on the left displacing the
cervical medullary junction towards the right. The L sigmoid sinus is decreased in
caliber, but enhances on the Stealth suggesting at least partial patency.
Differentials (for lesions arising within the CPA):
• Vestibular schwannoma / Acoustic neuroma
• Meningioma
• Epidermoid tumor
•Less likely: Arachnoid cyst, Non-acoustic cranial nerve schwannomas,
Vascular malformations, Dermoids, Teratomas, and Lipomas.
Discussion
•Acoustic neuromas
– Most common CPA lesion
– Middle to late decades of life
– Usually unilateral
– Benign and slow growing
– Characteristic features include:
•centered at porus acousticus
•acute angle to petrous bone
•involvement of IAC
•no dural tail
•no calcifications
•lack prominent vasculature
•never penetrate into middle cranial fossa
– Homogenous mass
– T1: isointense to brain and hyperintense to CSF
– T2: hyperintense to brain and iso/hypointense to CSF on T2
– Intense enhancement on T1 post contrast
Discussion
•Meningiomas
– 2nd most common CPA lesion
– Characteristic features:
•Obtuse angles to petrous bone
•Do not extend into IAC
•Often have dural tail
•Commonly demonstrate calcification
– May show flow voids of pial blood vessels
– Heterogeneous masses w possible central clearing
– T1: isointense to brain
– T2: between brain and CSF in intensity
– Post contrast: not as intense enhancement as acoustic neuroma
Discussion
•Epidermoid tumors
– 3rd most common CPA lesion
– Congenital lesions
– Present in adulthood
– Stratified squamous epithelium which surrounds a mass of keratin debris
– Benign and slow growing
– Facial weakness, paralysis, and spasm
– Expand into nearby structures
– Homogenous lesion
– T1: very low intensity, isointense to CSF
– T2: very bright, isointense to CSF
Diagnosis
AcousticNeuroma
References
1.
Bailey, Byron J. Head and Neck Surgery – Otolaryngology. Lippincott. New York,
NY. 2001.
2.
Brackmann, Shelton, Arriaga. Otologic Surgery. W.B. Saunders Company, New
York. 2001.
3.
Fisch, Mattox. Microsurgery of the Skull Base. Georg Thieme. New York, NY. 1988.
4.
Lang, Johannes. Clinical Anatomy of the Posterior Cranial Fossa and its
Foramina. Thieme Medical Publishers, Inc. 1991.
5.
McElveen, Dorfman. “Petroclival Tumors” Otolaryngology Clinics of North America.
2001, 34: 1219-1230.
6.
Mendenhall, et al. “Management of Acoustic Neuroma” American Journal of
Otolaryngology. 2004; 25: 38-47.
7.
Myers, et. al. Operative Otolaryngology. Head and Neck Surgery. Saunders
Company. Philadelphia, PA. 1997.
8.
Som, Curtin. Head and Neck Imaging. Mosby. St. Louis, MO. 2003.