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 16-year-old boy presented progressive visual disturbance that started 5 months prior with headache. The headache had subsided; however, the visual symptoms persisted. His visual acuity was 0.02 in his left eye and 0.3 in his right eye. The Goldmann perimetry field test revealed a large central scotoma of his left eye field and a temporal hemianopsia of his right eye field (). Brain MR imaging showed a heterogeneous hemorrhagic mass in the optic chiasm, extending posteriorly along the bilateral optic tracts with no definitive contrast enhancement (). The presumptive diagnosis was an unusual CM involving the optic pathway. Following left pterional craniotomy and sylvian dissection, the optic chiasm, which was mottled with dark dots, was visualized. A small window was made on the lateral side of the optic chiasm. Chocolate-colored tissue mixed with old blood was partially evacuated (). The pathology report confirmed the diagnosis of CM. Following surgery, the patient's visual acuity in his left eye slightly improved (0.03/0.3). The central scotoma of his left eye field had resolved; however, he subsequently acquired a nasal hemianopsia in his left eye field. At the patient's 2-year follow-up, there were no episodes of headache, visual change, or documented bleeding on serial MR imaging ().