Chih-Hsiang Liao

An easy adjustable method of ectatic vertebrobasilar artery transposition for microvascular decompression

BACKGROUND Microvascular decompression (MVD) of trigeminal neuralgia (TN) or hemifacial spasm (HFS) caused by an elongated, tortuous or enlarged vertebral or basilar artery has a higher rate of incomplete cure. OBJECTIVE We used an easily applied and adjustable method of vertebrobasilar artery transposition and fixation to improve the immediate surgical outcome of MVD of TN or HFS due to compression by an ectatic vertebrobasilar artery system. METHODS Vertebral or basilar artery transposition was performed using the vascular sling with a strip of unabsorbable dural tape. The vertebrobasilar artery-sling complex was then fixed to the dura over the petrous bone by aneurysm clip through the dural bridge. The direction and angle of traction on the vertebrobasilar artery was adjustable using different lengths of clip or the horizontal level of the dural bridge. RESULTS The sling and clip fixation method has been applied in 7 cases of MVD associated with vertebral or basilar artery compression. All 3 patients with TN and one with HFS had total remission of symptoms right after the procedure; one patient was completely free of spasm within 1 week after MVD and one had achieved 80% improvement of spasm in his last clinical visit 3 months after MVD. There was no major surgical complication in these 7 patients. Surprisingly, refractory hypertension was unexpectedly cured in one patient with TN following the procedure. CONCLUSION The vertebrobasilar artery transposition and fixation method used in the present study provided surgeons an easy and adjustable way to perform MVD safely and effectively.

Brainstem auditory evoked potential monitoring and neuro-endoscopy: Two tools to ensure hearing preservation and surgical success during microvascular decompression

Background: The effectiveness of microvascular decompression (MVD) has made trigeminal neuralgia (TN), hemifacial spasm (HFS), glossopharyngeal neuralgia, and other cranial nerve rhizopathy diseases treatable by surgery. To ensure hearing preservation and surgical success, we have presented our experience in the application of brainstem auditory evoked potential (BAEP) monitoring and neuro‐endoscopy during MVD. Methods: From July 2007 to October 2012, a total of 93 patients in our institution received MVD for cranial nerve rhizopathies. Among these patients, 43 had both BAEP monitoring and endoscope‐assisted microsurgery for their MVD. None of the patients had undergone previous surgical treatment. Postoperative outcomes were assessed based on the medical records and clinical follow‐up. Results: This study included 32 women and 11 men. There were 36 HFS cases and seven TN cases, and the median patient age at the time of MVD was 48 years. The median duration of symptoms before MVD was 4.2 years, and the median follow‐up duration was 3.5 years (range 1.5 months–5 years). All of the patients had either immediate or delayed complete relief from the symptoms after MVD. One TN patient underwent gamma knife radiosurgery 3 years after MVD, and two HFS cases had recurrent slight spasms, which warranted no further treatment. There was no surgical mortality. The major complications included one HFS patient with delayed and permanent hearing loss and facial palsy, which occurred 1 week after MVD. The surgical success rate was 100%, and the hearing complication rate was 2%. Conclusion: The results of this retrospective study emphasized the importance of BAEP monitoring and neuro‐endoscopy during MVD. It is well known that BAEP monitoring can preserve hearing function, and the endoscope offers neurosurgeons a second look to identify the nerve root entry zone and confirms the position of the Teflon felt. These two tools are especially useful in difficult cases.

Fluorescence-assisted visualization of facial nerve during mastoidectomy: A novel technique for preventing iatrogenic facial paralysis

OBJECTIVE Mastoidectomy can be risky due to the chance of iatrogenic facial nerve dysfunction. Avoiding injuries to the mastoid segment of the facial nerve is mandatory when drilling the bone. With advancements in intraoperative near-infrared indocyanine green (ICG) video angiography, we describe the application of a novel fluorescent guidance technique during mastoidectomies to identify the facial canal with safety. METHODS Mastoidectomies were performed as the key step in the presigmoid, petrosal or translabyrinthine approaches in 16 patients with different pathologies located at the cerebellopontine angle or petroclival region. After the facial canal was drilled to paper thin, ICG was injected via the central venous catheter. Compared with the dark bony portion, the vessels inside the vasa nervorum were highlighted as a result. The fluorescence guides the operator through the course of the facial nerve and facilitates opening of the internal auditory canal and the dissection of tumors. RESULTS All 16 facial nerves were recognized during mastoidectomies under fluorescence guidance for varied periods of enhancing time (range, 23-50s). In all, one to four attempts after repeated drilling works to enhance the facial nerve were required before these nerves could be clearly seen. The tumor resection procedure yielded the following results: grossly total removal in seven patients, near total removal in five, and subtotal removal in three. Complete obliteration of a giant vertebral artery aneurysm in one patient was seen in the follow-up angiogram. The post-mastoidectomy facial nerve function, examined by triggered EMG, was preserved in all 16 patients, and no patients had postoperative facial palsy worse than House-Brackmann grade IV after 6 months of follow-up. CONCLUSION With this novel technique, the course of the facial nerve can be confirmed during mastoidectomy, which reduces the possibility of iatrogenic facial nerve dysfunction. This fluorescence technique is especially helpful in establishing confidence and shortening the learning curve for beginners at mastoidectomies.

Primary large B-cell lymphoma of the fourth ventricle

We present a patient with an isolated primary central nervous system lymphoma (PCNSL) of the fourth ventricle. A 77-year-old man had a 1 week history of intermittent vertigo, nausea, vomiting, and progressively unsteady gait. CT scans of the brain showed a fourth ventricle tumor. MRI revealed a 2.5 cm dumbbell-shaped avidly-enhancing tumor in the fourth ventricle. Metastasis or high-grade glioma was suspected. The neuropathological findings were compatible with a diffuse large B-cell lymphoma. A slit lamp examination, bone marrow biopsy, and imaging studies for extracranial lesions were unremarkable. We suggest that PCNSL be listed in the differential diagnosis of fourth ventricle tumors with well-circumscribed margins and homogenous contrast enhancement.

Comparison of the effectiveness of using the optic strut and tuberculum sellae as radiological landmarks in diagnosing paraclinoid aneurysms with CT angiography.

OBJECTIVE The treatment of paraclinoid aneurysms remains challenging. It is important to determine the exact location of the paraclinoid aneurysm when considering treatment options. The authors herein evaluated the effectiveness of using the optic strut (OS) and tuberculum sellae (TS) as radiographic landmarks for distinguishing between intradural and extradural paraclinoid aneurysms on source images from CT angiography (CTA). METHODS Between January 2010 and September 2013, a total of 49 surgical patients with the preoperative diagnoses of paraclinoid aneurysm and 1 symptomatic cavernous-clinoid aneurysm were retrospectively identified. With the source images from CTA, the OS and the TS were used as landmarks to predict the location of the paraclinoid aneurysm and its relation to the distal dural ring (DDR). The operative findings were examined to confirm the definitive location of the paraclinoid aneurysm. Statistical analysis was performed to determine the diagnostic effectiveness of the landmarks. RESULTS Nineteen patients without preoperative CTA were excluded. The remaining 30 patients comprised the current study. The intraoperative findings confirmed 12 intradural, 12 transitional, and 6 extradural paraclinoid aneurysms, the diagnoses of which were significantly related to the type of aneurysm (p < 0.05) but not factors like sex, age, laterality of aneurysm, or relation of the aneurysm to the ophthalmic artery on digital subtraction angiography. To measure agreement with the correct diagnosis, the OS as a reference point was far superior to the TS (Cohens kappa coefficients 0.462 and 0.138 for the OS and the TS, respectively). For paraclinoid aneurysms of the medial or posterior type, using the base of the OS as a reference point tended to overestimate intradural paraclinoid aneurysms. The receiver operating characteristic curve indicated that if the aneurysmal neck traverses the axial plane 2 mm above the base of the OS, the aneurysm is most likely to grow across the DDR and present as a transitional aneurysm (sensitivity 0.806; specificity 0.792). CONCLUSIONS High-resolution thin-cut CTA is a fast and crucial tool for diagnosing paraclinoid aneurysms. The OS serves as an effective landmark in CTA source images for distinguishing between intradural and extradural paraclinoid aneurysms. The DDR is supposed to be located 2 mm above the base of the OS in axial planes.

A giant Suprasellar Rathke cleft cyst with psychiatric manifestations: Case report

Rathke cleft cyst (RCC) is a benign, cystic remnant of the cranopharyngeal duct, typically located in the sellar region [1]. Purely uprasellar RCC situated above a normal sella is rare [2]. The comon clinical presentations of symptomatic RCCs include headache, isual impairment, and endocrine disturbance. Descriptions of psyhiatric manifestations associated with RCCs were exceedingly are [2–8], and their potential neuropsychiatric significance may e underestimated. In this report, the authors presented the case f a giant suprasellar RCC with psychiatric manifestations which esolved spontaneously after surgical intervention.

Microsurgical technique of symptomatic intracavernous aneurysm.

Symptomatic intracavernous aneurysm is rare. Cranial nerves in the cavernous sinus are subjected to the mass effect of an expanding aneurysm. Microsurgical clipping is the treatment of choice to relieve compressive cranial neuropathy. In this video, the authors present a case of intracavernous aneurysm causing diplopia, ptosis, and facial numbness. The patient was operated on via a pretemporal transclinoid-transcavernous approach. The aneurysm was completely obliterated through direct clipping. There were no new-onset neurologic deficits and complications after the operation. Complete recovery of the diplopia, ptosis, and facial numbness was observed at the 6-month postoperative follow up. The video can be found here: http://youtu.be/4w5QUoNIAQM.