Cisternal Segment Research Articles

Isolated Oculomotor Nerve Palsy Following Minor Head Trauma : Case Illustration and Literature Review

Isolated oculomotor nerve palsy (ONP) attributable to mild closed head trauma is a distinct rarity. Its diagnosis places high demands on the radiologist and the clinician. The authors describe this condition in a 36-year-old woman who slipped while walking and struck her face. Initial computed tomography did not reveal any causative cerebral and vascular lesions or orbital and cranial fractures. Enhancement and swelling of the cisternal segment of the oculomotor nerve was seen during the subacute phase on thin-sectioned contrast-enhanced magnetic resonance images. The current case received corticosteroid therapy, and then recovered fully in 13 months after injury. Possible mechanism of ONP from minor head injury is proposed and previous reports in the literature are reviewed.

Histopathological effects of radiosurgery on a human trigeminal nerve

Background:Radiosurgery is a well-established treatment modality for medically refractory trigeminal neuralgia. The exact mechanism of pain relief after radiosurgery is not clearly understood. Histopathology examination of the trigeminal nerve in humans after radiosurgery is rarely performed and has produced controversial results.Case Description:We report on a 45-year-old female who received radiosurgery treatment for trigeminal neuralgia by Cyberknife. A 6-mm portion of the cisternal segment of trigeminal nerve received a dose of 60 Gy. The clinical benefit started 10 days after therapy and continued for 8 months prior to a recurrence of her previous symptoms associated with mild background pain. She underwent microvascular decompression and partial sensory root sectioning. Atrophied trigeminal nerve rootlets were grossly noted intraoperatively under surgical microscope associated with changes in trigeminal nerve color to gray. A biopsy from the inferolateral surface of the nerve proximal to the midcisternal segment showed histological changes in the form of fibrosis and axonal degeneration.Conclusion:This case study supports the evidence of histological damage of the trigeminal nerve fibers after radiosurgery therapy. Whether or not the presence and degree of nerve damage correlate with the degree of clinical benefit and side effects are not revealed by this study and need to be explored in future studies.

Transcranial magnetic resonance–guided focused ultrasound surgery for trigeminal neuralgia: a cadaveric and laboratory feasibility study

Transcranial MR-guided focused ultrasound surgery (MRgFUS) is evolving as a treatment modality in neurosurgery. Until now, the trigeminal nerve was believed to be beyond the treatment envelope of existing high-frequency transcranial MRgFUS systems. In this study, the authors explore the feasibility of targeting the trigeminal nerve in a cadaveric model with temperature assessments using computer simulations and an in vitro skull phantom model fitted with thermocouples. Six trigeminal nerves from 4 unpreserved cadavers were targeted in the first experiment. Preprocedural CT scanning of the head was performed to allow for a skull correction algorithm. Three-Tesla, volumetric, FIESTA MRI sequences were performed to delineate the trigeminal nerve and any vascular structures of the cisternal segment. The cadaver was positioned in a focused ultrasound transducer (650-kHz system, ExAblate Neuro, InSightec) so that the focus of the transducer was centered at the proximal trigeminal nerve, allowing for targeting of the root entry zone (REZ) and the cisternal segment. Real-time, 2D thermometry was performed during the 10- to 30-second sonication procedures. Post hoc MR thermometry was performed on a computer workstation at the conclusion of the procedure to analyze temperature effects at neuroanatomical areas of interest. Finally, the region of the trigeminal nerve was targeted in a gel phantom encased within a human cranium, and temperature changes in regions of interest in the skull base were measured using thermocouples. The trigeminal nerves were clearly identified in all cadavers for accurate targeting. Sequential sonications of 25-1500 W for 10-30 seconds were successfully performed along the length of the trigeminal nerve starting at the REZ. Real-time MR thermometry confirmed the temperature increase as a narrow focus of heating by a mean of 10°C. Postprocedural thermometry calculations and thermocouple experiments in a phantom skull were performed and confirmed minimal heating of adjacent structures including the skull base, cranial nerves, and cerebral vessels. For targeting, inclusion of no-pass regions through the petrous bone decreased collateral heating in the internal acoustic canal from 16.7°C without blocking to 5.7°C with blocking. Temperature at the REZ target decreased by 3.7°C with blocking. Similarly, for midcisternal targeting, collateral heating at the internal acoustic canal was improved from a 16.3°C increase to a 4.9°C increase. Blocking decreased the target temperature increase by 4.4°C for the same power settings. This study demonstrates focal heating of up to 18°C in a cadaveric trigeminal nerve at the REZ and along the cisternal segment with transcranial MRgFUS. Significant heating of the skull base and surrounding neural structures did not occur with implementation of no-pass regions. However, in vivo studies are necessary to confirm the safety and efficacy of this potentially new, noninvasive treatment.

Three-dimensional microsurgical anatomy of cerebellar peduncles

The microsurgical anatomy of cerebellar peduncles and their relationships with neighbouring fasciculi were investigated by using a fibre dissection technique. As the dissection progressed, photographs of each progressive layer were obtained and stereoscopic images were created using the 3D anaglyphic method. These findings provided the anatomical basis for a conceptual division of cerebellar peduncles into segments. The middle cerebellar peduncle (MCP) was divided into two segments: cisternal and intracerebellar segments. The inferior cerebellar peduncle (ICP) was divided into three segments: cisternal, ventricular and intracerebellar segments. The superior cerebellar peduncle (SCP) was divided into three segments: intracerebellar, intermediate and intrategmental segments. The fibre dissection technique disclosed a constant course of peduncular fibres inside the white core of the cerebellum. The pontocerebellar fibres of the MCP pass over and laterally to the bundles of the ICP and SCP. The centripetal fibres of the ICP wrap around the radiation of the SCP and the dentate nucleus, directed towards the cortex of the vermis. The centrifugal bundle of the SCP ascends towards the mesencephalon where it sinks passing below the fibres the lateral lemniscus. The knowledge gained by studying the intrinsic anatomy of the cerebellum is useful to accomplish appropriate surgical planning and, ultimately, to understand the repercussions of surgical procedures on the white matter tracts in this region.

The nervus intermedius as a variable landmark and critical structure in cerebellopontine angle surgery: an anatomical study and classification

An understanding of the normal topography during cerebellopontine angle surgery is necessary to obviate the anatomical distortions caused by tumors. The aim of this study was to analyze the morphological features of the nervus intermedius (NI) and its related structures in the cerebellopontine angle (CPA). Forty-three isolated human brainstems were examined to collect comprehensive morphometric and topographical data of the NI in its course from the brainstem to the ganglion geniculi, and discover its anatomical relationship with the other neurovascular structures in the CPA as well as within the meatus acusticus internus. A total of 84 NI were analyzed. The number of bundles comprising the NI varied from one to five. The mean length of the cisternal segment of the NI was 11.47 mm. In most cases, a vein between the root entry/exit zones of the facial and the vestibulocochlear nerve (VN) was documented. In all cases the NI joined the facial nerve, typically (85 %) distally to the the porus within the meatus acusticus internus. The entry/exit zone of the NI can be categorized into four types: in type A, they arise directly from the brainstem; in type B, they arise solely from the facial nerve; in type C solely from the VN; and in type D, where the bundle or bundles arise from both the brainstem and the VN or the facial nerve. The anatomical features of the NI can provide an additional variable landmark and critical structure during cerebellopontine microsurgery. Our study of the nerve's anatomy and topographical relations may contribute to preventing intraoperative nerve injuries.

MRI assesment of internal acoustic canal variations using 3D-FIESTA sequences

Magnetic resonance imaging (MRI) of the internal acoustic canal is the standard diagnostic tool for a wide range of indications in patients. This study aims to investigate the vascular variations and compression of the cranial nerves (CNs) VII and VIII at the cerebellopontine angle in patients with neuro-otologic symptoms using 3D-fast imaging employing steady-state acquisition (FIESTA) MR imaging. One hundred and eighty-seven patients (374 temporal bones) were examined on a 1.5-T MRI. In addition to conventional MR sequences, a 3D-FIESTA MR imaging was acquired. Magnetic resonance images thus obtained were evaluated with special regard to the presence of vascular contact to the CNs VII and VIII, as well as the presence of the vascular variations of the anterior inferior cerebellar artery (AICA) causing the compression of CNs. The Chi-squared test was used for statistical analysis. No statistically significant differences were found between the presence and absence of the AICA loop and/or vascular contact for the clinical symptoms of patients (P > 0.05). The cisternal and canalicular segments of CNs VII and VIII and adjacent vascular variations are well identified using 3D-FIESTA, especially by determining the relationship of the AICA variations between CNs.

Microvascular decompression on patients with trigeminal neuralgia caused by ectatic vertebrobasilar artery complex: technique notes

Due to its anatomical features, the vertebrobasilar artery complex (VBA) seldom contributes to the neurovascular conflict in patient with trigeminal neuralgia (TN). However, once it offends the trigeminal root, this large artery is really difficult to manipulate during microvascular decompression (MVD) surgery. Therefore, the surgical strategy for such cases needs to be detailed in order to obtain a satisfactory outcome. From 2009 through 2011, 475 consecutive TN patients underwent MVDs in our department. Among them, ten were found in which an ipsilateral deviating ectatic vertebrobasilar artery complex (VBA) offended the trigeminal nerve. Those cases were focused on in this study and each operation was analyzed retrospectively. During the operation, the vertebral artery was regarded as the direct culprit in six (60 %) patients, while the basilar artery in four (40 %). As companions, some smaller vessels were also observed to be close to the nerve, including the superior cerebellar artery (SCA) in five, veins in two and anterior inferior cerebellar artery (AICA) in two. The neurovascular conflict was discovered in the cisternal segment of the trigeminal root in eight, while in the root entry zone (REZ) in two. In six out of the ten cases, the affected nerves were demonstrated to be squeezed towards the tentorium by the ectatic VBA. Postoperatively, the symptom of pain totally disappeared immediately in eight (80 %) patients, while it was relieved apparently in two (20 %). During the follow-up period of 3-30 months, no recurrence or complication was found, except for one patient who had numbness of the face. With a proper strategy, MVD is probably the most effective therapy for the TN cases caused by ectatic vertebrobasilar artery complex. The substance of the surgery is to withdraw the proximal vertebral artery caudally via a lateroinferior cerebellar approach.

Facial Schwannomas: Various Presentations and their Management with Literature Review

Facial schwannomas or neuromas are rare entity. They often are confused with vestibular schwannomas on imaging, especially if they are limited to the cisternal segment of the facial nerve. Awareness regarding this entity is paramount for the early diagnosis and correct management which may differ from patient to patient. We share the different clinical presentations of this rare benign tumour and discuss their management strategies in light of the affected segment of the nerve. The results were analyzed along with review of literature. Three cases of facial schwannomas were analyzed retrospectively during last 4years and their presentation, imaging, preferred surgical approaches, intra-operative findings and post grafting results are discussed. All three patients underwent surgical excision with sural nerve cable grafting and have no recurrence till date. However, the facial paresis remained the same in one of the cases while improvement was observed in two patients. The improvement was delayed in one patient as documented by electromyography of facial muscles. Facial schwannomas are slow growing tumours with low incidence. Usual presentations can sometimes be masked. Appropriate management decision needs to be arrived after considering three determinants i.e. the patient's age, hearing status and the severity of facial paresis (House-Brackmann grading). Nerve reconstruction after excision should be performed in each case and sometimes the results may be delayed. It is thus important to keep a close surviellance during the follow up and to perform the electrophysiological tests frequently so as to detect the earliest signs of regeneration (which can be delayed up to 18months).

Endoscopic endonasal approach for a tuberculum sellae meningioma.

The authors present the technical and anatomical nuances needed to perform an endoscopic endonasal removal of a tuberculum sellae meningioma. The patient is a 47-year-old female with headaches and an incidental finding of a small tuberculum sellae meningioma with no vascular encasement, no optic canal invasion, but mild inferior to superior compression of the cisternal segment of the left optic nerve. Neuroophthalmology assessment revealed no visual defects. Treatment options included clinical observation with imaging follow-up studies, radiosurgery, and resection. The patient elected to undergo surgical removal and an endonasal endoscopic approach was the preferred surgical option. Preoperative radiological studies showed the presence of an osseous ring between the left middle and anterior clinoids, the so-called carotico-clinoidal ring. The surgical implications of this finding and its management are illustrated. The surgical anatomy of the suprasellar region is reviewed, including concepts such as the chiasmatic sulcus and limbus sphenoidale, medial and lateral optico-carotid recesses, and the paraclinoidal and supraclinoidal segments of the internal carotid artery. Emphasis is made in the importance of exposing the distal dural ring of the internal carotid artery and the precanalicular segment of the optic nerve for adequate intradural dissection. The endonasal route allows for early coagulation of the tumor meningeal supply and extensive resection of dural attachments, and importantly, provides an inferior to superior access to the infrachiasmatic region that facilitates complete tumor removal without any manipulation of the optic nerve. The lateral limit of dural removal is formed by the distal dural ring, which is gently coagulated after the tumor is resected. A 45° scope is used to inspect for any residual tumor, in particular at the entrance of the optic nerve into the optic canal and at the most anterior margin of the exposure (limbus sphenoidale). The steps for reconstruction are detailed and include intradural placement of dural substitute and extradural placement of the nasoseptal flap. The nuances for proper harvesting, positioning, and reinforcement of the flap are described. No lumbar drain was used. The patient had an uneventful recovery with no CSF leak or any other complications. Imaging follow-up at 6 months showed complete removal of the tumor. The patient had no sinonasal or neurological symptoms, and olfaction was fully preserved. The video can be found here: http://youtu.be/kkuV-yyEHMg .

The central myelin–peripheral myelin transitional zone of the nervus intermedius and its implications for microsurgery in the cerebellopontine angle

The central myelin-peripheral myelin transitional zone, also referred to as the "Obersteiner-Redlich zone (ORZ)" or "glial/Schwann junction" of the nervus intermedius, is thought to play a role in the pathophysiology of nervus intermedius neuralgia (NIN). To evaluate the location and histological features of the ORZ of the nervus intermedius (NI), 10 NI specimens from five fresh cadavers were microscopically analyzed for structural differences between their central and peripheral myelin segments. The ORZ was analyzed under a light microscope, and the exact location of the ORZ was confirmed by immunohistochemical staining using an oligodendroglial antibody. The total diameter of the NI showed a mean of 0.62 mm. The cisternal segment of the NI from the brain stem to the porus acusticus internus had a mean length of 13.97 mm. The mean extent of central myelin was 0.5 mm from the brain stem on the medial side and 0.33 mm on the lateral side. Moreover, the mean length of the ORZ was 0.279 mm on the medial side and 0.134 mm on the lateral side. The distance between the brain stem and the most distal point of central myelin that could be detected was 0.67 mm. Accordingly, the ORZ of the NI appears closer to the brain stem compared to the other cranial nerves. The exact location of the ORZ may play a role in diagnostic preoperative imaging, in the planning of surgical procedures for NIN, and may offer suitable landmarks for surgeons performing microvascular decompression in NIN treatment.

Apport de l’IRM dans le syndrome de Stilling-Duane : résultats préliminaires

Duane retraction syndrome (DRS) is a congenital ocular motility disorder with innervational dysgenesis. MRI improves our understanding of this disease by providing in vivo access to nerves and oculomotor muscles. The goal of this prospective study (2000-2008) was to analyze DRS clinically and neuroradiologically. Twenty-four patients (27 eyes) received a complete ophthalmologic evaluation and a brain-orbital MRI. The average age was 6.1 years. MRI was performed with 3D T2 CISS-weighted images through the brainstem to visualize the cisternal segments of the cranial nerves and the orbit (lateral and medial recti muscles). MRI anomalies were classified according to type I, II, and III and depending on their condition in the posterior fossa (absence, hypoplasia) and in the orbit (muscle anomalies). Of 27 eyes, 70% were type I, 19% type II, and 11% type III. MRI showed abducens nerve abnormalities in 93% of the cases (78% absence) and muscle abnormalities in 57.5% of the cases. A detailed description showed 100% abducens nerve abnormalities and 58% abnormal lateral rectus muscle in type I, 60% abducens nerve abnormalities and 60% abnormal lateral rectus muscle in type II, and 100% abducens nerve abnormalities and 66% abnormal lateral rectus in type III. This study presents two major findings: detection of abducens nerve abnormalities in most cases of DRS whatever the type, associated with muscle abnormalities, and the confirmation that this absence may exist in type II (2/5). Thus MRI proved to be a valuable tool for investigating these patients, improving the comprehension of the physiopathogenics of this disease.

Lung cancer presenting with trigeminal neuropathy

The purpose of this case report is to describe MR imaging and CT findings of a patient in whom the first clinical and neuroradiological manifestation of a metastatic lung adenocarcinoma was unilateral trigeminal neuropathy caused by a presumed metastasis involving cisternal and Meckel's cave segments of ipsilateral trigeminal nerve. MR imaging and CT scan differential diagnosis of expansive lesions of the intracranial trigeminal nerve must include metastases. Physicians and neuroradiologists must be aware of metastases as an uncommon cause of trigeminal neuropathy, even as the presenting condition of cancer.

Cavernous Malformation of the Trochlear Nerve: Case Report and Review of the Literature on Cranial Nerve Cavernomas

Cavernous malformations (CMs) arising intrinsically to the cisternal segment of the trochlear nerve are extremely rare. This case of a trochlear nerve cavernous angioma is the third to be reported in the neurosurgical literature and the first to be resected by a middle fossa approach. The authors present a case of a 31-year-old woman with progressive left-sided headache and left hemisensory symptoms, whose magnetic resonance imaging showed a solid enhancing tumor in the left ambient cistern at the level of the midbrain-pontine junction causing significant brainstem compression. Intraoperatively, a left trochlear nerve cavernous angioma circumferentially enveloping the nerve was visualized. The angioma was microsurgically resected by a middle fossa approach under frameless stereotactic guidance. Gross total resection of the intrinsic trochlear nerve lesion was achieved, although the trochlear nerve could not be preserved intact. CMs should be considered in a possible differential diagnosis of cisternal trochlear nerve tumors. Surgical resection remains the standard of care, and is indicated for relief of compressive symptoms and prevention of future bleeds. Postoperative diplopia often persists; however, resolution of diplopia reported in the literature can be attributed to either regeneration after direct surgical repair of the sacrificed nerve or a spontaneous adaptation over time.

Aberrant course of the intracranial facial nerve in cases of atresia of the internal auditory canal (IAC)

The aim of this study is to describe the morphology of the rare malformation that is atresia of the internal auditory canal (IAC) and determine the course of the facial nerve in cases of normal facial nerve function. Index cases were retrospectively selected from our electronic database in which all inner ear malformations presenting to a tertiary referral center between 1995 and 2010 are collected. Computed tomography (CT) data and magnetic resonance (MR) images were reviewed by two neuroradiologists. An otolaryngologist analyzed the patients' clinical data. Nine ears of six patients (three bilateral, three unilateral) with atresia of the IAC were identified. All patients presented with sensory neural hearing loss. Two of these unilaterally affected patients had facial nerve palsy. In the other seven cases of complete atresia of the IAC, the facial nerve was dislocated in its cisternal segment close to the trigeminal nerve. Where the nerve fibers enter the Gasserian ganglion, the facial nerve takes a sharp lateral turn and enters a minute canal by which it reaches the geniculate ganglion. In the two ears with facial nerve palsy, this pathway could not be identified. In atresia of the IAC, the facial nerve takes a ventral and superior course, with its own canal starting at the point where the trigeminal nerve enters the Gasserian ganglion. Facial nerve palsy points to absence of this aberrant temporal facial nerve canal.

Middle Skull Base Approach With Posterolateral Mobilization of the Geniculate Ganglion to Access the Clival Regions

Clival lesions remain one of the most challenging intracranial tumors to treat surgically. Many skull base approaches have been described to improve resection and to decrease patient morbidity. To describe a middle skull base approach with posterolateral mobilization of the geniculate ganglion of the facial nerve to access the clival regions. Three patients with petroclival chordoma and 1 patient with petroclival meningioma underwent surgical resection of lesions with our new procedure. Surgical techniques consisted of temporal craniotomy and exposure of the facial nerve from the tympanic segment to the labyrinthine segment, keeping the fundus of the internal auditory canal intact. The geniculate ganglion was mobilized posterolaterally, followed by drilling of the cochlea and exposure of the Dorello canal. Four lesions were successfully removed with complete preservation of facial nerve function. This approach is a modification of the Goel procedure in which the facial nerve from the tympanic segment to the cisternal segment was totally mobilized. Our procedure carries less risk to the facial nerve function than the Goel procedure and provides sufficiently wide exposure of clival lesions.

Trigeminal Neuralgia due to Neurovascular Compression: High-Spatial-Resolution Diffusion-Tensor Imaging Reveals Microstructural Neural Changes

To preoperatively detect, by using diffusion-tensor imaging coregistered with anatomic magnetic resonance (MR) imaging, suspected microstructural tissue changes of the trigeminal nerves in patients with trigeminal neuralgia (TN) resulting from neurovascular compression. The study was approved by the institutional review board, and written informed consent was obtained from all patients. Twenty patients (mean age, 51.3 years) with TN and evidence of neurovascular contact were examined with use of a 3.0-T MR unit combined with an eight-channel head coil before undergoing surgical decompression. A single-shot diffusion-tensor echo-planar sequence was used along 15 different diffusion directions, with a b value of 1000 sec/mm(2) and a section thickness of 2 mm. For anatomic correlation, 0.6-mm isotropic three-dimensional fast imaging employing steady-state images were acquired for coregistration with the functional diffusion-tensor maps. After region of interest placement, mean fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were calculated for each nerve by using the paired-sample two-tailed t test (with P < .005 indicating significance) and compared with surgical findings. FA was significantly lower (P = .004) on the trigeminal neuralgia-affected side (mean FA, 0.203) than on the contralateral side (mean FA, 0.239). ADCs were nearly identical between the normal and TN-affected nerve tissues. These findings suggest that diffusion-tensor imaging enables the identification and quantification of anisotropic changes between normal nerve tissue and TN-affected trigeminal nerves. Coregistration of anatomic three-dimensional fast imaging employing steady-state imaging and diffusion-tensor imaging facilitates excellent delineation of the cisternal segments of the trigeminal nerves.

“Far-Medial” Expanded Endonasal Approach to the Inferior Third of the Clivus

The endoscopic endonasal transclival approach is a valid alternative for treatment of lesions in the clivus. The major limitation of this approach is a significant lateral extension of the tumor. We aim to identify a safe corridor through the occipital condyle to provide more lateral exposure of the foramen magnum. Sixteen parameters were measured in 25 adult skulls to analyze the exact extension of a safe corridor through the condyle. Endonasal endoscopic anatomic dissections were carried out in nine colored latex-injected heads. Drilling at the lateral inferior clival area exposed two compartments divided by the hypoglossal canal: the jugular tubercle (superior) and the condylar (inferior). Completion of a unilateral ventromedial condyle resection opens a 3.5 mm (transverse length) * 10 mm (vertical length) lateral surgical corridor, facilitating direct access to the vertebral artery at its dural entry point into the posterior fossa. The supracondylar groove is a reliable landmark for locating the hypoglossal canal in relation to the condyle. The hypoglossal canal is used as the posterior limit of the condyle removal to preserve more than half of the condylar mass. The transjugular tubercle approach is accomplished by drilling above the hypoglossal canal, and increases the vertical length of the lateral surgical corridor by 8 mm, allowing for visualization of the distal cisternal segment of the lower cranial nerves. The transcondylar and transjugular tubercle "far medial" expansions of the endoscopic endonasal approach to the inferior third of the clivus provide a unique surgical corridor to the ventrolateral surface of the ponto- and cervicomedullary junctions.

Imaging the hypoglossal nerve

The hypoglossal nerve is a pure motor nerve. It provides motor control to the intrinsic and extrinsic tongue muscles thus being essential for normal tongue movement and coordination. In order to design a useful imaging approach and a working differential diagnosis in cases of hypoglossal nerve damage one has to have a good knowledge of the normal anatomy of the nerve trunk and its main branches. A successful imaging evaluation to hypoglossal diseases always requires high resolution studies due to the small size of the structures being studied. MRI is the preferred modality to directly visualize the nerve, while CT is superior in displaying the bony anatomy of the neurovascular foramina of the skull base. Also, while CT is only able to detect nerve pathology by indirect signs, such as bony expansion of the hypoglossal canal, MRI is able to visualize directly the causative pathological process as in the case of small tumors, or infectious/inflammatory processes affecting the nerve. The easiest way to approach the study of the hypoglossal nerve is to divide it in its main segments: intra-axial, cisternal, skull base and extracranial segment, tailoring the imaging technique to each anatomical area while bearing in mind the main disease entities affecting each segment.

Ruptured Aneurysm Arising from the Anterior Choroidal Artery's Cisternal Segment

Ruptured Aneurysm Arising from the Anterior Choroidal Artery's Cisternal Segment

Application of the Willis Covered Stent in the Treatment of Aneurysm in the Cisternal Segment of the Internal Carotid Artery: A Pilot Comparative Study With Midterm Follow-up

To compare the use of the Willis stent-graft versus coil embolization for complicated aneurysms in the cisternal segment of the internal carotid artery (ICA). Thirty-four patients (19 women; mean age 46.7+/-16.8 years, range 3-79) with 36 complicated aneurysms were treated either by Willis covered stents (n = 19) or by coil embolization (n = 17). Follow-up angiography was performed to investigate aneurysm recurrence, endoleak, and parent artery stenosis. Kaplan-Meier curves were constructed to compare the freedom from recurrence and parent artery stenosis rates in both groups. Clinical follow-up data were retrospectively analyzed and categorized as fully recovered, improved, unchanged, or worsened. In the covered stent group, total exclusion was immediately achieved in 13 aneurysms; there were 5 minor endoleaks and 1 delivery failure. In the patients treated with coil embolization, total/near-total occlusion was achieved in 7 aneurysms, subtotal in 8, and partial in 2. Acute thrombosis occurred in 1 patient in each group, while 1 patient experienced recurrent hemorrhage after embolotherapy. Follow-up angiography (mean 14.3+/-9.4, range 3-31) revealed that 16 aneurysms were completely isolated in the stent-graft group, with only 2 mild in-stent stenoses. Eighteen months after the procedure, Kaplan-Meier analysis showed recurrence-free rates of 93.3% and 50% for the stent-graft versus coil groups, respectively; freedom from parent artery stenosis was 87.5% and 100%. Symptoms were fully eliminated in 9 patients in each group; they were improved in 3 and 5, unchanged in 2 and 2, and worsened in 1 and 0, respectively, at the end of the follow-up period. Willis stent-graft application is an alternative to treat complicated aneurysms in the cisternal segment of the ICA. In the case of a tortuous parent artery or potential side branch coverage, however, it is still not a first choice therapy.