Ibrahim M. Ziyal

Natural History of Brainstem Cavernous Malformations

OBJECTIVE: To review the natural history and determine the rates of intra- and extralesional hemorrhaging of brainstem cavernous malformations (cavernomas) monitored by one neuro-ophthalmology service. METHODS: A record review of all patients with brainstem cavernomas who were evaluated by a neuroophthalmology service between 1987 and 1999 was performed. We recorded the clinical symptoms and Rankin disability grade at presentation, during the worst clinical episode, and at the last follow-up examination. Magnetic resonance imaging scans were reviewed for evidence of intralesional hemorrhage (a bleeding episode), edema, or venous anomalies, and the cavernoma size was assessed. RESULTS: Thirty-seven patients (age range, 6-73 yr; mean age at presentation, 37.5 yr) underwent a mean of 4.9 years of follow-up monitoring. At presentation, there were 27 bleeding events and 8 nonhemorrhagic events; 2 patients did not exhibit symptoms. Patients who were at least 35 years of age exhibited a lower risk of bleeding episodes (odds ratio, 0.15; 95% confidence interval, 0.1-0.4). Cavernomas of at least 10 mm were associated with a higher risk of bleeding episodes (odds ratio, 3.48; 95% confidence interval, 1.3-9.4). Thirty-nine bleeding episodes occurred in 31 patients, yielding a bleeding rate of 2.46%/yr. There were eight rebleeding episodes, yielding a rebleeding rate of 5.1%/yr. Three patients experienced extralesional bleeding episodes; all of these patients experienced rebleeding. Of the 39 follow-up magnetic resonance imaging scans, the cavernoma size was unchanged in 66.7%, smaller in 18%, and larger in 15%. At the last follow-up examination, the mean Rankin grade was 1.0 for all patients, 0.6 for the 25 nonsurgically treated patients, and 1.4 for the 12 surgically treated patients. CONCLUSION: Rebleeding is not more common among patients who first present with bleeding, and it often has little effect on the neurological status of patients. Significant morbidity attributable to a brainstem cavernoma occurred in 8% of patients during follow-up monitoring of medium duration.

Preliminary results of auditory brainstem implantation in prelingually deaf children with inner ear malformations including severe stenosis of the cochlear aperture and aplasia of the cochlear nerve.

Objective: The aim of our study is to present the results of 11 children where auditory brainstem implantation (ABI) was successfully performed to restore hearing. Study Design: Case presentation. This study was conducted at the departments of Otolaryngology and Neurosurgery at Hacettepe University Ankara, Turkey. Patients: Between July 2006 and April 2008, 11 prelingual (30-56 mo) deaf children with several cochlear malformations had ABI. Intervention: All patients were programmed and were enrolled in auditory verbal therapy sessions and family counseling programs at Hacettepe Auditory Verbal Center. The evaluation was performed at preimplant and again 1, 3, 6, 9, and 12 months post-switch on. Main Outcome Measures: The main test components composing this test battery were Ling 6 Sound Detection-Identification Test, Word Identification Test in Turkish, Meaningful Auditory Integration Scale, and Meaningful Use of Speech Scale. Results: Successful brainstem implantations were performed in all patients with retrosigmoid approach. Six children gained basic audiologic functions and were able to recognize and discriminate sounds, and many could identify environmental sounds such as a doorbell and telephone ring by the third month of ABI. Improvement in mean performance on Meaningful Auditory Integration Scale is apparent for all ABI children. Improvement in Meaningful Use of Speech Scale scores in 2 patients, demonstrating that the child using its own voice for speech performance, was observed between the baseline and 12th month. First, 5 children were able to identify Lings 6 sound by the end of 2 to 6 months, and 2 of them also started to identify words due to their pattern differences and multisyllabic word identification by 6 to 9 months. Two children with Attention Deficit Hyperactivity Disorder have made slower progress than the other children with ABIs. Conclusion: Our preliminary results show that there is adequate contribution of brainstem implants in the development of auditory-verbal skills. Additional handicaps slow the progress of the prelingually deaf children.

Microanatomy of the central myelin-peripheral myelin transition zone of the trigeminal nerve.

OBJECTIVE:The aim of this study was to evaluate the microanatomy of the central myelin-peripheral myelin transitional zone (TZ) in trigeminal nerves from cadavers. METHODS:One hundred trigeminal nerves from 50 cadaver heads were examined. The cisternal portion of the nerve (from the pons to Meckel’s cave) was measured. Horizontal sections were stained and photographed. The photomicrographs were used to measure the extent of central myelin on the medial and lateral aspects of the nerve and to classify TZ shapes. RESULTS:The cisternal portions of the specimens ranged from 8 to 15 mm long (mean, 12.3 mm; median, 11.9 mm). The data from the photomicrographs revealed that the extent of central myelin (distance from pons to TZ) on the medial aspect of the nerve (range, 0.1–2.5 mm; mean, 1.13 mm; median, 1 mm) was shorter than that on the lateral aspect (range, 0.17–6.75 mm; mean, 2.47 mm; median, 2.12 mm). CONCLUSION:The data definitively prove that the root entry zone (REZ, nerve-pons junction) and TZ of the trigeminal nerve are distinct sites and that these terms should never be used interchangeably. The measurements showed that the central myelin occupies only the initial one-fourth of the trigeminal nerve length. If trigeminal neuralgia is caused exclusively by vascular compression of the central myelin, the problem vessel would always have to be located in this region. However, it is well known that pain from trigeminal neuralgia can resolve after vascular decompression at more distal sites. This suggests that the effects of surgical decompression are caused by another mechanism.

Auditory brainstem implantation.

The use of cochlear implants for selected individuals with bilateral severe to profound sensorineural hearing loss who derive limited benefit from conventional hearing aids is well established. There are situations where cochlear implantation is contraindicated. Auditory brainstem implantation (ABI) is the only solution to restore hearing when the cochlear nerve is disrupted together with pathologies where the cochlea does not provide a suitable location for cochlear implant. Labyrinthine and cochlear aplasia and cochlear nerve aplasia constitute the congenital indications for ABI. In the present review article history and development of ABI, indications, side selection criteria, surgery and audiological outcome are presented.

A glioma with an arteriovenous malformation: an association or a different entity?

Case reportA 58-year-old male was admitted with headache to our neurosurgery clinic. His neurological examination revealed slight left hemiparesis. The radiological evaluation with contrast administred magnetic resonance imaging (MRI) scan demonstrated a right temporo-parietal ring enhancing mass lesion surrounded by edema which was resembling a typical glioma (Fig. 1). The patient was operated on via a temporo-parietal craniotomy and an arteriovenous malformation surrounded by abnormal glial tissue was observed during the exposure. A nidus supplied by several branches arising from the middle cerebral artery (MCA) was obvious. The venous drainage of the malformation was to the superficial venous system. The observed arterial feeders and the draining vein were coagulated and the nidus was macroscopically totally excised. The frozen examination from surrounding glial tissue revealed a high grade glioma. The tumor was also macroscopically totally excised. Postoperatively, the cerebral angiogram demonstrated a right temporal arteriovenous malformation with a centrally excised nidus. The remaning major feeders involved the angular gyrus and the posterior temporal arteries. The venous drainage was to the straight and sigmoid sinuses (Fig. 2). The final histopathological examination of the specimen revealed an arteriovenous malformation surrounded by a high grade glioma (Fig. 3). The patient refused a second operation for total removal of the AVM. Postoperatively, he is doing well with improvement of his left hemiparesis.

Early improvement of bilateral abducens nerve palsies following surgery of an anterior communicating artery aneurysm.

A 43-year-old male su¤ered from sudden headache, nausea and vomiting two days before admission to an emergency service. Computed tomographic (CT) showed a subarachnoid hemorrhage filling the anterior supratentorial, prepontine and perimesencephalic cisterns (Fig. 1). Next day, when admitted to our clinic, he was alert and had nuchal rigidity with a WFNS grade of 2. Neurological examination showed bilateral abducens nerve palsies (Fig. 2A). An emergency digital substraction angiography (DSA) demonstrated a sacculer aneurysm on the anterior communicating artery (Fig. 3). The patient underwent operation on the next day, via a right pterional approach. After opening the Sylvian fissure, it was observed that the basal cisterns were obstructed with clot; this was extensively removed and the aneurysm clipped. The subarachnoid space was irrigated with saline solution several times. DSA two days later demonstrated successful clipping of the anterior communicating aneurysm (Fig. 4). His bilateral abducens nerve palsies resolved on the third postoperative day (Fig. 2C and D).

Epidermoid cyst of the brain stem symptomatic in childhood

BackgroundEpidermoid cysts may remain asymptomatic for a long period of time due to their slowly growing pattern corresponding with the normal human skin turnover time and due to soft and light cyst content. They do not cause compression of neural and vascular structures initially that is why almost all of the cases in the literature are diagnosed during adulthood.MethodsWe report here an epidermoid cyst in childhood, which was located in the medulla oblongata, unusually and atypically with liquefied cyst content. The liquefaction may occur due to an intrauterine or early childhood infection. The reported case also suffered previously a severe respiratory infection. Although the cyst is located in and around a highly eloquent neural area, plasticity of the brain stem prevented neurological deterioration due to this very slow growing extraaxial mass lesion. The ordinary cyst content found in the center of the cyst cavity during the operation suggested that the same ordinary material, which was previously at the periphery, ran to get liquefied in time.ConclusionWe suggest that the symptoms of this present case appeared very early due to liquefaction of the cyst content with compression and displacement of the brain stem caudally. The recent infection process may predispose the pathological condition.

Bilateral Temporal Bone Xanthomas in Type II Hypercholesterolemia.

We present a very rare case of intracranial xanthoma with bilateral temporal bone involvement. The lesion caused destruction and remodelling in mastoid air cells. On the right side, cerebellar compression was obvious. The patient was operated on the symptomatic side and the lesion was totally removed.

Does ventricular opening promote remote cerebellar haemorrhage

Cerebellar haemorrhage after supratentorial craniotomy is a rare complication Because of its significant morbidity and mortality rates, being aware of this complication is important for early diagnosis. In a 30-year-old male with multiple intracranial cavernomas, remote cerebellar haemorrhage (RCH) was observed after removal of symptomatic left temporal lesion. The lateral wall of the temporal horn that was tightly attached to the cavernoma was also opened and excessive drainage of the CSF occurred. The haemorrhage is attributed to opening of the ventricle wall and excessive drainage of cerebrospinal fluid (CSF) during the procedure.

Spontaneous nonpulsatile aneurysm of the superficial temporal artery mimicking a subcutaneous mass lesion.

True superficial temporal artery (STA) aneurysms are extremely rare and usually atherosclerotic in origin. Here the authors report a 62-year-old man with a nonpulsatile mass lesion at the trace of the right STA that was surgically excised with a preoperative diagnosis of subcutaneous mass lesion, preoperatively and histopathologically found out to be a thrombosed true STA aneurysm. Preoperative evaluation, differential diagnosis, and management of such lesions are discussed.