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 17-year-old boy complained of a 2-month history of visual field defects. Two months prior to this, he experienced sudden deterioration of visual acuity on his left eye and visual field defects on the right. His symptoms remained unchanged for the next 2 months. Upon admission, his visual acuity was 0.05 in the left eye and 0.7 in the right eye. Goldmann perimetry field test showed right homonymous hemianopsia without left eye foveal sparing. Brain MR imaging showed a poorly enhanced lesion 1.9 × 1.7 × 2.1 cm in size in the posteroinferior aspect of the optic chiasm (). The mass extended to the perimesencephalic cistern with multiple stages of hemorrhage. A differential diagnosis included CM, craniopharyngioma and germ cell tumor. To decompress the mass effect around the optic chiasm and improve the patient's visual symptoms, surgical decompression via subfrontal interhemispheric approach was performed. A brownish discoloration was noted around the left side of optic chiasm and tract. A dark chocolate-colored hematoma gushed out, and a mulberry-like lesion was removed. The pathological diagnosis was consistent with the CM. The postoperative MR imaging showed partial resection of CM (). At the patient's 1-year follow-up, his visual acuity improved (1.0/0.4), although visual field defect remained unchanged. However, 2 years after the first operation, the patient complained of worsening visual acuity (0.3/finger count 10 cm). Visual field examination showed impairments in which the left eye only detected the right lower quadrant in the visual field and the right eye had nasal hemianopsia. MR imaging revealed recurrent bleeding (). The patient underwent a second operation resulting in a partial resection. Immediately following the second operation, his visual acuity (0.4/finger count 10 cm) and field improved slightly.