A 29-year-old woman diagnosed with multiple malignant melanomas in 1996 was operated on after frontal hemorrhage due to malignant transformation of the right frontal lobe, with hematoma and resection of the vascular lesion.
That same year, a small 3 mm diameter probanded angioma was observed.
Asymptomatic patient was admitted until January 2004, when he presented headache and vomiting associated with hemihypoesthesia with paresthesia of the right hemibody and right hemiparesis 4/5.
The physical examination revealed a vertical nystagmus, a right hemiparesis 4/5 and a right hemihypoesthesia with extinction.
On admission, a cranial CT scan showed a 20 mm diameter mass protruding distal hematoma related to the already known location of the cavernoma.
1.
Brain MRI confirmed the presence of an angiocephalangeal surface of the left ventricle protruding into the trunk and the presence of perilesional hemosiderin that defined growth and bleeding of the lesion, which deformed the fourth ventricle.
1.
Given the clinical and radiological progression of the lesion it was decided to surgically intervene, using intraoperative monitoring consisting of stimulation of the surface of the rhomboid fossa to determine the location of the nuclei of the left XII cranial nerves VII and X
Intraoperative auditory potentials were also performed.
To stimulate the nuclei located in the rhomboid fossa we used the NIM-Response® System (Medtronic, XOMED) nervous monitoring system applying a monophasic rectangular voltage pulse stimulus.
The maximum intensity applied was 2 mA.
The stimulus duration was 100 μseconds and the frequency was 10 Hz.
The electromyographic reading was performed with electrodes placed with a separation of 5 mm in bipolar arrangement to cover the representative muscle area.
Electrodes for facial nerve monitoring were placed in the orbicularis oris muscles of the mouth and eye.
To record the XII cranial nerve, the electrodes were placed in the genioglossal muscle.
The recording of the X pair was performed with sensors of the vocal cords located in the anesthesia tube.
The patient was placed in prone position, performing a suboccipital craniectomy and exeresis of the posterior arch of C1.
After dural and arachnoid opening and under microscopic control, the height of the left facial colliculus was observed.
After anatomical identification of nuclei X and XII, their functionality was confirmed with intraoperative stimulation with positive electromyographic response.
The facial nucleus was located only by stimulation, finding very lateral, at the border between the angle of the rhomboid fossa and the middle cerebellar peduncle.
The nucleus was probably laterally displaced by the mass effect of the hematoma that was not visualized on the surface.
A pial incision was made, the hematoma that was evaccinated was located, as well as the cavernoma that caused it.
At the end of the resection, monitoring of the involved nuclei was repeated, obtaining an electromyographic response in all, although the intensity of the facial nerve, especially the orbicularis oris oris, had descended.
The auditory potentials were maintained with the same response as in the preoperative period.
Postoperatively, the patient developed a transient paresis of X and XII, which resolved completely at 48 hours and was suspected due to the blockade produced by repeated electrical stimulation.
He also presented persistent internuclear palsy with one and a half syndrome that has partially recovered, a nuclear paresis of the left VI nerve, as well as a nuclear facial paresis that has progressively improved.
As for long roads, no motor deficit was observed, although there was instability while walking without help, independently.
The level of consciousness is good, with preserved cognitive superior functions.
