Case 2: trigeminal schwannoma (post. cavernous sinus)

posted: 4/29/96

Resident: Bruce Hamilton, MD
Attending Staff: Deepak Awasthi, MD

This 38 year old woman presented to the clinic with an one year history of double vision on the right progressively worsening since December of 1995. In addition, the patient stated that approximately 4 months after the start of double vision, she started experiencing severe right facial pain (in the cheek and temporomanibular joint area). This pain would sometimes last for several hours and had no specific trigger point. Patient underwent a root canal for this facial pain- without relief. This pain was progressively replaced by numbness in the right cheek since January of 1996. Patient also complains of occasional mild to moderate frontal headache. The family noted that over the previous month the patient's right eye deviates inward at rest. Patient denies any decline in vision or hearing, or any other neurological complaints. Of note, the patient had a MRI scan of the brain (without contrast) approximately a year ago (at the time of double vision)- this was read as normal.

EXAMINATION: Patient was awake, alert and in no distress. Motor, sensory (except right face) and cerebellar examination was normal. Relexes were normal bilaterally with no pathological reflex. The gait was normal. Cranial nerves I-IV and VII-XII were normal bilaterally; all cranial nerves were normal on the left. On the right side, there was a partial VIth nerve paresis and diminished sensation to pinprick and light touch in the right V2 distribution. The corneal sensation and reflex was also diminished on the right. Remainder of the examination was normal.

Where would you localize the lesion and what would be your differential diagnosis?

Please comment: AwasBrainS@aol.com

Above images are post-contrast T1-weighted MRI scans- coronal (left) and axial (right). Above images demonstrate a homogenously enhancing mass (2x3cm) near the posterolateral edge of the right cavernous sinus and near the petrosu apex, on the floor of the middle fossa.

What is your differential diagnosis and how will you manage this lesion- what surgical approaches?

Please comment: AwasBrainS@aol.com

STEPS TAKEN AT LSU: The patient was taken to the operating room and through a "modified" right "pterional" craniotomy (combined pterional and anterior subtemporal) the antereolateral aspect of the right middle fossa was approached. The proximal Sylvian fissure as well as the carotid cistern were opened and the neurovascular structures visualized (right optic nerve, internal carotid artery and IIIrd nerve). The lesion was seen in the posterolateral edge of the cavernous just anterior to the petrous apex in middle fossa- see below:

Note the right internal carotid artery and third nerve in the left corner of the photograph (under the tentorial edge). The sylvian fissure has been split and the temporal lobe retracted posteromedially. Note the bulge (tumor) in the upper right corner of the photograph- pointed by the dissector.

The tumor was fully resected. The mass displaced the VIth nerve medially and the trigeminal nerve (V2 and V1) inferiorly. The trigeminal nerve appeared flattened.

PATHOLOGY: Schwannoma

POSTOPERATIVE COURSE: Patient did well postoperatively. She was awake and alert. She reported an improvement in the double vision. However, the right sided numbness was worse (especially in the V2 division). Corneal sensation on the right was preserved.

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