A 21-year-old man was admitted to our clinic with a sudden and progressive headache and binocular diplopia. His symptoms had appeared 2 months before his first visit to the clinic. He had also experienced a similar attack 6 months earlier, but he was in a good general condition. The neurological examination revealed right-sided abducens nerve palsy. A brain computed tomography (CT) scan was acquired, which showed a suspected lesion in the cerebellopontine angle. Brain CT angiography was also performed, which did not reveal any prominent findings. The brain MRI showed an extra-axial pontomedullary lesion with the classic appearance of a CM, that is, a reticulated salt-and-pepper core, surrounded by a halo rim []. With the diagnosis of brain stem CM with a history of multiple hemorrhages, progressive neurological deficit, and pial presentation of the CM, the patient was enlisted for the surgical resection of the lesion.\nThe patient underwent surgery using the suboccipital retrosigmoid approach with intraoperative neuromonitoring. The procedure was performed through general anesthesia as the patient laid in a lateral position, and his head was fixed in a three-pin Mayfield headrest. After opening the dura, a CM was detected, arising from the sixth cranial nerve, with no invasion to the brainstem or the surrounding tissues. Since the lesion could not be separated from the nerve and its integrity was unclear, we resected the CM by cutting the proximal and distal portions (before the Dorello’s canal) of the sixth cranial nerve []. Intraoperative monitoring was used to detect changes in the function of the nervous structure. Motor and somatosensory evoked potentials were normal during the surgery. Direct nerve stimulation of the sixth nerve was also performed during the surgery. The response to stimulation was normal when stimulating distal to the lesion and weak proximal to the lesion.\nThe greater auricular nerve (>3 cm) was harvested as an interposition nerve graft. An anastomosis was performed using a fibrin glue sealant, as end-to-end suture was impossible. One day after surgery, the patient showed complete sixth nerve palsy. He was discharged on the 4th postoperative day, without any neurological deficit, except for the right abducens nerve palsy. In the 5-month follow-up visit, he showed complete recovery of the cranial deficit and diplopia. The histopathological examination of the lesion demonstrated typical characteristics of a CM []. To determine the origin of the lesion, immunohistochemistry staining for the S100 marker was carried out, and the results showed the intraneural origin of the lesion []. The follow-up imaging was normal after 2 years, and the patient was symptom free during this period.
A 26-year-old man was admitted for recurrent headaches, loss of vision in his left eye, and elevated blood pressure. His loss of sight had been gradual, manifesting for over six months before hospitalization. He also exhibited episodes of inadequate behavior with some aggression. The patient was conscious at admission, and no other meningeal or focal neurological symptoms were found. The patient consented to publication of his protected health information.\nHis right and left eyes had logarithm of the minimum angle of resolution visual acuities of 1.0 and 0.2, respectively. T1-weighted magnetic resonance imaging (MRI) showed a hyperintense signal mass lesion occupying his chiasm and left ON (Figure ). These findings led to a diagnosis of high-grade glioma of the chiasm and left ON, or CM.\nSurgery was performed with the patient in the supine position, with his head slightly elevated and turned to the right side about 30 degrees. A left frontolateral craniotomy was performed to optimize the approach to the chiasm and left ON. Fenestration of the basal cistern and aspiration of cerebrospinal fluid yielded a relaxed brain with satisfactory gravity retraction. The left optic canal was unroofed, and several blood clots at different stages of resorption were evacuated through the longitudinal dissection of the ON. Minimal coagulation currents were applied to occlude the feeding vessels with their sharp sections. Resection was estimated to be gross total (Video ).\nThere were no surgical complications, and MRI performed six months later showed no signs of CM recurrence (Figure ). The patient was discharged after seven days, and his vision returned to normal three months later. He is still in touch with us and has reported no signs of visual deterioration or recurrent bleeding.\nThe microscopic structure of the resected CM with heterochromous thromboses is shown in Figure .