Nikolaos Georgakoulias

Untethering of herniated left optic nerve after dopamine agonist treatment for giant prolactinoma.

Dear Editor, Reviewing the pituitary literature, secondary deterioration of the visual field due to optic chiasm herniation after dopaminergic agonist medical therapy for macroprolactinomas and giant prolactinomas is a relatively rare but not unknown entity [1–4]. The suggested treatment of this complication is gradual reduction of the medical treatment and systematic visual field evaluation. Furthermore, dopamine agonist-related morbidities (i.e. cerebrospinal fluid leakage or chiasmal herniation) are considered among the indications for late surgery of giant prolactinomas, proposed by Shrivasta et al. [5]. In June 2012, a patient presented with right-eye blindness, known for the last 3 years, and progressive deterioration of his left-eye visual field over the last 3 weeks, while being on dopamine agonist treatment for a giant prolactinoma that was diagnosed in December 2011. Expecting further tumour enlargement, a pituitary magnetic resonance imaging (MRI) scan was conducted, which, to our surprise, revealed further shrinkage of the tumour and herniation of the inferomedial portion of the right frontal lobe, optic chiasm and anterior circulation vascular complex into the enlarged sella vacated by the involuted tumour. The patient underwent craniotomy, and through a transglabelar approach with drilling of the cribriform plate, entrance into the sphenoid sinus and opening of the anterior wall of sella, the tumour was unsurprisingly recognised, extensively fibrous, with scarring and dense adhesions to the surrounding neurovascular structures. The right optic nerve was found remarkably degenerated, while the left optic nerve was identified, preserved and untethered along with the anterior communicating artery (AcomA) complex from the tumour capsule. The tumour was resected in a piecemeal fashion, except for portions with fibrous adhesions to the AcomA complex and optic chiasm. A post-operative pituitary MRI scan revealed excision of the residual tumour to a great extent and untethering of the left optic nerve and AcomA complex (Fig. 1). The left eye visual function was substantially improved and the patient was referred to the endocrinology department for further treatment. In this case, the great risk of impeding total blindness and the narrow time frame for dose reduction led us to decide upon urgent surgical management. The expected intense fibrosis and overall scarring promoted by the almost 6-month dopamine agonist treatment [6], and the inferior and leftward traction of the optic chiasm and AcomA complex into the partially emptied and enlarged sella made a transcranial approach more appropriate. Given these facts, using an endoscopic trans-sphenoidal approach the risk of neurovascular damage would be unacceptably high, while untethering the left optic nerve all the way from the optic canal to the optic chiasm would seem to be almost impossible. Furthermore, the major advantage of the craniotomy approach is that it affords a complete view of the pituitary tumour’s effect on intracranial structures, which can be safely preserved during tumour removal [7–10]. The transglabelar approach enabled the control of all neurovascular structures around the tumour, while the drilling of the cribriform plate and opening the anterior wall of sella through the sphenoid sinus gave us access to the residual prolactinoma and herniated structures of the sella, enabling the safe untethering and preservation of the left optic nerve. N. Gkekas (*) : P. Primikiris :N. Georgakoulias Department of Neurosurgery, Athens General Hospital G. Gennimatas, Mesogeion 154, Athens, Greece P.C. 11526 e-mail: nikolaosgkekasdr@yahoo.gr

The medial loop of the V2 segment of the vertebral artery and the importance of this variation in correlation with the resection safe zone and technical characteristics of spinal cages during anterior cervical approaches

Dear Editor, Reviewing the literature, the incidence of anatomic variations of the V2 segment of the vertebral artery (VA), is relatively high. Furthermore, ignoring a medial loop of the V2 segment can potentially lead to severe complications during anterior approaches to the cervical spine. We studied the course of 400 vertebral arteries on 190 magnetic resonance imaging and ten contrast-enhanced computed tomography scans from our archive between May 2011 and June 2012. In our study, patients with MRI or CT axial sections from C3 to C7 were included regardless of the underlying pathology. In nine patients (4, 5 %), the V2 segment of the vertebral artery formed a medial loop with distance to the midline 8 mm and 8 mm except in one level (one in 360 cervical levels) [4]. Furthermore, anterior cervical diskectomy 8–10 mm from the midline and width of cervical corpectomy 16–18 mm centered on the midline have been suggested in the literature as safe resection zones [3]. The width and adequacy of cervical corpectomy remains a controversial topic, especially in cases of an unusual medial loop of the V2 segment. It could be technically challenging to avoid the injury of VA and achieve an adequate anterior decompression. Careful choice of cages regarding their width is a prerequisite for anterior cervical diskectomy and corpectomy procedures. According to our study, during drilling for anterior cervical approaches, this variation is likely to be encountered at 7–11 mm depth of vertebral body or intervertebral disk space. In such cases, the application of intraoperative Doppler could be invaluable. Knowledge of the aforementioned anatomic variation of the V2 segment is important for the avoidance of inadvertent injury of the vertebral artery during anterior cervical spine approaches [2], with potentially catastrophic complications for the patient. Given the relatively high incidence of a V2 N. Gkekas (*) :N. Georgakoulias Department of Neurosurgery, Athens General Hospital, G. Gennimatas, Mesogeion 154, Athens, Greece 11526 e-mail: nikolaosgkekasdr@yahoo.gr

Hydrocephalus due to Membranous Obstruction of Magendie's Foramen

We report a case of non communicating hydrocephalus due to membranous obstruction of Magendies foramen. A 37-year-old woman presented with intracranial hypertension symptoms caused by the occlusion of Magendies foramen by a membrane probably due to arachnoiditis. As far as the patients past medical history is concerned, an Epstein-Barr virus infectious mononucleosis was described. Fundoscopic examination revealed bilateral papilledema. Brain magnetic resonance imaging demonstrated a significant ventricular dilatation of all ventricles and turbulent flow of cerebelospinal fluid (CSF) in the fourth ventricle as well as back flow of CSF through the Monros foramen to the lateral ventricles. The patient underwent a suboccipital craniotomy with C1 laminectomy. An occlusion of Magendies foramen by a thickened membrane was recognized and it was incised and removed. We confirm the existence of hydrocephalus caused by fourth ventricle outflow obstruction by a membrane. The nature of this rare entity is difficult to demonstrate because of the complex morphology of the fourth ventricle. Treatment with surgical exploration and incision of the thickened membrane proved to be a reliable method of treatment without the necessity of endoscopic third ventriculostomy or catheter placement.

Duplication of the dura as a cause of anterior thoracic spinal cord herniation. A case report

Abstract The authors report the surgical management of anterior thoracic spinal cord herniation through a defect of the inner layer of a duplicated dura mater in a 55-year-old patient presenting with a 5-year history of progressive myelopathy, addressing the possible pathogenesis and the surgical treatment options of this rare entity.

Multifocal low-grade gliomas: Adapting the optimal therapeutic management

Abstract The authors report the rare and first documented case in the literature of a surgically treated patient with multifocal low-grade glioma comprising left frontotemporoinsular ganglioglioma of World Health Organization (WHO) grade I and right temporal lobe astrocytoma of WHO grade II.

Postoperative Rhinorrhea without Intraoperative Cerebrospinal Fluid Leak After Endoscopic Transnasal Transphenoidal Surgery for Pituitary Macroadenomas

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Acute onset of trigeminal neuralgia, facial paresis and dysphagia after mild head injury

Abstract The authors report the rare and first documented case of concomitant microvascular decompression of trigeminal, facial and glossopharyngeal nerves for the management of intractable to medical therapy acute onset of trigeminal neuralgia, facial paresis and dysphagia after mild head injury.

De novo intracranial collision tumour in previously evacuated intracerebral haematoma site.

The authors report the rare and first documented case of intracranial collision tumour occurrence in a previously evacuated intracerebral haematoma site. Surgery trauma could predispose to collision tumour occurrence. Research efforts should try to reveal the possible pathogenesis of this condition.