Intracranial Course Research Articles

The Course of the Trochlear Nerve Presented via a 3-Dimensional Photorealistic Anatomic Model

Several factors contribute to the anatomical complexity of the trochlear nerve, including small diameter, complex and longest intracranial course, deep location, and numerous neurovascular relationships. A 3-dimensional (3D) photorealistic model of the cranial nerves provides a detailed and immersive representation of the anatomy, enabling one to improve surgical planning, advanced surgical research, and training. The purpose of this work is to present a 3D photogrammetric study for a more intuitive and interactive way to explore and describe the entire course of trochlear nerve. Two injected-fixed head human specimens (4 sides) were examined. The dissection protocol was divided into the following steps: 1) brain hemisphere exposure; 2) hemispherectomy dissecting all cranial nerves and partial removal of the free edge of the tentorium; 3) middle fossa and lateral wall of cavernous sinus exposure; and 4) orbital exposure. A detailed 3D photogrammetric model was generated for each dissection step. Four main volumetric models were generated during a step-by-step layered dissection of the entire nerve pathway highlighting its different segments. Finally, a full and integrated model of the entire course of the nerve was created. The models are available for visualization on monoscopic display, virtual, and augmented reality environment. The present photogrammetric model provides a more comprehensive understanding of the nerve's anatomy in its different segments, allows for customizable views thus simulating different perspectives, and can be a valuable alternative to traditional dissections. It is an advanced tool for surgical planning and surgical simulation as well as virtual reality representation of the anatomy.

Assessment of prevalence of vascular contact of the facial nerve in asymptomatic patients using three-dimensional constructive interference in steady-state (3D CISS) MRI acquisition.

To evaluate the prevalence of vascular contact of the facial nerve in patients without hemifacial spasm or facial palsy using magnetic resonance imaging (MRI). Our radiology database was accessed to find a series of consecutive adult patients who underwent MRI of the brain during the study period, excluding those with a history of hemifacial spasm (HFS), facial palsy, traumatic brain injury, intracranial tumour, intracranial surgery, trigeminal neuro-vascular compression, brain radiation therapy, and studies with poor image quality. A total of 112 (224 sides) MRIs of the posterior fossa were independently reviewed by 2 radiologists for neurovascular contact involving the facial nerve. The presence of neuro-vascular contact, the number of points of contact, the location of contact along the intracranial course of the facial nerve, the culprit vessel, and the severity of compression were recorded in the CISS MRI sequence in the cohort of patients without HFS and facial palsy. The prevalence of neurovascular contact involving the facial nerve can be as high as 51% in patients asymptomatic for HFS and facial palsy. It is frequently caused by the anterior inferior cerebellar artery and commonly involves the cisternal portion with mild to moderate severity. In asymptomatic patients, the pulsatile neurovascular contact of the intracranial segment of the facial nerve typically occurs at one point, involving the distal portion with milder severity in contrast to patients with HFS. These results in the asymptomatic cohort should be considered when evaluating the candidacy of HFS patients for microvascular decompression.

Simplified Easy-Accessible Smartphone-Based Photogrammetry for 3-Dimensional Anatomy Presentation Exemplified With a Photorealistic Cadaver-Based Model of the Intracranial and Extracranial Course of the Facial Nerve.

Smartphone-based photogrammetry (SMPhP) was recently presented as a practical and simple algorithm to create photorealistic 3-dimensional (3D) models that benefit from volumetric presentation of real anatomic dissections. Subsequently, there is a need to adapt the techniques for realistic depiction of layered anatomic structures, such as the course of cranial nerves and deep intracranial structures; the feasibility must be tested empirically. This study sought to adapt and test the technique for visualization of the combined intracranial and extracranial course of the facial nerve's complex anatomy and analyze feasibility and limitations. We dissected 1 latex-injected cadaver head to depict the facial nerve from the meatal to the extracranial portion. A smartphone camera alone was used to photograph the specimen, and dynamic lighting was applied to improve presentation of deep anatomic structures. Three-dimensional models were created with a cloud-based photogrammetry application. Four 3D models were generated. Two models showed the extracranial portions of the facial nerve before and after removal of the parotid gland; 1 model showed the facial nerve in the fallopian canal after mastoidectomy, and 1 model showed the intratemporal segments. Relevant anatomic structures were annotated through a web-viewer platform. The photographic quality of the 3D models provided sufficient resolution for imaging of the extracranial and mastoid portions of the facial nerve, whereas imaging of the meatal segment only lacked sufficient precision and resolution. A simple and accessible SMPhP algorithm allows 3D visualization of complex intracranial and extracranial neuroanatomy with sufficient detail to realistically depict superficial and deeper anatomic structures.

Risk factors for postoperative seizures in patients with chronic subdural haematomas

Postoperative seizures are a frequently occurring yet not well-understood complication in patients undergoing surgical treatment of chronic subdural haematomas (cSDHs). Therefore, we investigated surgical and non-surgical risk factors that are commonly considered causal in provoking epileptic seizures, paying special attention to the intracranial course of the subdural drain (SDD) and the configuration of the haematoma. Data of patients with a cSDH, that were treated at our neurosurgical department between 2008 and 2014 were analysed. Patients suffering from severe pre-existing conditions and those who have been treated conservatively were excluded. Epidemiologic data as well as relevant clinical data were collected. Pre- and postoperative CT scans were analysed regarding morpho- and volumetric parameters. In order to objectify the influence of the SDD, its intracranial course and localisation (entering angle as well as the angle between drain and brain surface) were measured. For statistical analysis, univariate and multiple logistic regression models as well as Fisher’s exact test were used. Two hundred eleven consecutive patients have been included. Mean age was 75.6 years, and 69% were male. Nineteen (9%) patients suffered from postsurgical seizures. Membranes within the haematoma were present in 81.5%. Pre- to postoperative haematoma reduction was significant (mean of difference − 12.76 mm/ − 9.47 mm in coronal/axial CT planes, p = 0.001/ < 0.001). In 77.9%, SDD showed cortical contact with eloquent regions and had an unfavourable course in 30 cases (14.2%). Surgical complications consisted of cortical bleeding in 2.5%, fresh subdural haematoma in 33.5% and wound infections in 1.4% of patients. Neither in univariate nor in multiple regression analyses any of the following independent variates was significantly correlated with postsurgical seizures: pre-existing epilepsy, alcohol abuse, right-sided haematomas, localization and thickness of haematoma, presence of septations, SDD-localization and to-brain angle, subdural air, and electrolyte levels. Instead, in multiple regression analyses, we found the risk of postsurgical seizures to be significantly correlated and increased with left-sided cSDH treated via craniotomy (p = 0.03) and an unfavourable course of the SDD in left-sided cSDH (p = 0.033). Burr hole trepanation should be preferred over craniotomy and care must be taken when placing a SDD to avoid irritating cortical tissue. The configuration of the haematoma does not appear to affect the postoperative seizure rate.

Optic nerve-associated connective tissue structures revisited: A histological study using human fetuses and adult cadavers.

Unlike the usual peripheral nerve, the optic nerve accompanies a thick "dural sheath," a thin "sheath of pia mater" (SPM), and multiple "septa," which divides the nerve fibers into fascicles. We collected specimens from 25 adult cadavers and 15 fetuses and revisited the histological architecture of the optic and oculomotor nerves. In the optic chiasma, the meningeal layer of the dura joins the pia to form a thick SPM, and the periosteum of the sphenoid is continuous with the dural sheath at the orbital exit of the bony optic canal. The septa appeared as a cluster of irregularly arrayed fibrous plates in the intracranial course near the chiasma. Thus, the septa were not derived from either the SPM or the dural sheath. In the orbit, the central artery of the retina accompanies collagenous fibers from the dural sheath and the SPM to provide the vascular sheath in the optic nerve. These connective tissue configurations were the same between adult and fetal specimens. At the optic disk, the dural sheath and SPM merged with the sclera, whereas the septa appeared to end at the lamina cribrosa. However, in fetuses without lamina cribrosa, the septa extend into the nerve fiber layer of the retina. The SPM and septa showed strong elastin immunoreactivity, in contrast to the absence of reactivity in the sheaths of the oculomotor nerve. Each S100 protein-positive Schwann sheath of the oculomotor nerve was surrounded by collagenous endoneurium. Glial fibrillary acidic protein-positive astrocytes showed a linear arrangement along the septa.

Unilateral absence of internal carotid artery: A rare case report

Unilateral absence of internal carotid artery (ICA) is a rare congenital anomaly. We present the case of a 35-year-old man with episodes of recurrent strokes in the past and now presenting with right-sided upper limb weakness. Radiological diagnostic workup revealed a thin left ICA in the neck with non-visualization beyond petrous bone in the intracranial course. The ipsilateral brain parenchyma is supplied by vessels from the contralateral side of the Circle of Willis. As the patient had no evidence of a cerebrovascular accident on radiological evaluation and no neurological signs and symptoms, he was discharged with anticoagulant medications with the advice of follow-up. This is the first report to describe a case of ICA agenesis with a pattern of collateral circulation that doesn’t fit any of the six types described by Lie.

MORPHOMETRIC STUDY OF ANTERIOR COMMUNICATING ARTERY IN HUMAN BRAINS IN UTTAR PRADESH : A CADAVERIC STUDY

Background: This study is important for radiologists and neurosurgeons as the anterior communicating artery is an important artery of blood supply of the brain and is also a part of the circle of Willis. It connects two anterior cerebral arteries across the commencement of longitudinal fissure. Different morphometric parameters like the direction of origin, intracranial course, diameter of the artery and number of arteries are studied in this study. Materials and Methods: A retrospective study was conducted over more than 2 years in the anatomy department, Subharti Medical College, Swami Vivekanand Subharti University, Meerut, Uttar Pradesh. A study was conducted on 50 human cadaveric brains, which were removed from the cadavers used for teaching purposes for undergraduate and postgraduate students. Dissection followed by measurement and pictorial documentation of the anterior communicating artery was done in all 50 specimens. Results: Of 50 cadaveric adult brains, 04% show an absent anterior communicating artery. 60% have an oblique course, and 36% have a horizontal course. 2.78 mm was the average length observed, and 1.08 mm was the average diameter of the artery. No extra pair of arteries was seen in any of the specimens. Conclusion: From this study, we can conclude that morphometrics of the anterior communicating artery is not rare. The artery's oblique and horizontal course was observed in many specimens along. In a few cadaveric brains, the anterior communicating artery was absent. This morphometrics of the anterior communicating artery is significant for neurosurgeons and radiologists.

Traumatic and Spontaneous Vertebral Artery Dissections: An Analysis of Tertiary-Center 310 Patient Cohort

Abstract BACKGROUND Vertebral artery dissections (VADs) are rare yet potentially devastating events. While the etiology of these events is either traumatic or spontaneous, there is a paucity of quantitative literature comparing the two. OBJECTIVE To identify differences in predisposing factors, event characteristics, and clinical outcomes between traumatic VADs (tVADs) and spontaneous VADs (sVADs). METHODS We retrospectively identified patients with VADs presenting to our institution at VAD onset with at least a 3-mo follow-up. Demographics, event characteristics, treatment details, and neurological outcomes as modified Rankin scale (mRS) scores were collected. RESULTS Of the 310 patients sustaining 366 VADs total, 187 (60.3%) patients experienced a total of 221 (60.4%) sVADs and 123 (39.7%) patients experienced a total of 145 (39.6%) tVADs. sVADs were more likely to occur in the intracranial course of the artery (P = .042) and have a lower mRS at discharge, 3-month, and last clinical follow-up (P = 003, .002, and .001, respectively). tVADs were more likely associated with concomitant fractures (P &lt; .001). CONCLUSION Despite similar patient populations, tVADs are associated with higher mRS scores at all time points. Although further study is needed, this may suggest other concomitant trauma rather than the VAD itself is contributing to worse neurological status in patients with tVADs.

Trochlear nerve palsy in a boxer after a bout

Superior oblique palsy as a result of injury to the cranial nerve (CN) IV (trochlear nerve) is the most frequent isolated CN palsy due to its long intracranial course. Isolated CN IV palsy has not been reported in combat sports. We report here a case of isolated CN IV palsy occurring after a boxing bout. Isolated CN IV palsy may present very subtly in a combat sports athlete and ringside physicians should be aware of its clinical presentation.

Traumatic orbital third nerve palsy

We present a case series of three patients who developed acute traumatic orbital third nerve palsies. To our knowledge, reported cases have mainly been localised to the intracranial course of the nerve and often associated with visual impairment. Those in which the orbit is the site of injury are rare. Our case series highlights the importance of careful preoperative assessment of patients with orbital trauma (particularly when there is a coexisting fracture) and the need to assess ocular movements and pupillary reactions to distinguish between a neurogenic and soft tissue injury. Early diagnosis is helpful in deciding on the timing of the operation and enables patients to be given appropriate counselling to make sure that their expectations are realistic.

Benign abducens nerve palsy: diagnosis by exclusion

Of all the cranial nerves, the abducens nerve has the longest intracranial course hence is most common cranial nerve to be affected secondary to any potentially devastating intracranial cause. It can indicate significant underlying pathology. Abducens or sixth cranial nerve innervates lateral rectus muscle and pathology of this nerve results in abduction deficiency of ipsilateral eye. Most of the time it will be unilateral but bilateral involvement is also well known. It can recurrent without any underlying identifiable pathology. The 6th nerve palsy is considered as benign after ruling out all possible causes. Benign causes account for just 9 to 14% of all 6th nerve palsies in children. Most of the time benign 6th nerve palsy occurs after viral infection or vaccination as an immunological reaction. In our case patient had history of pentavalent vaccination 1 month back. After thorough investigation and ruling out all possible causes it was attributed to post vaccination immunological reaction. which resolved spontaneously over 4months.

The Intracranial and Intracanalicular Optic Nerve as Seen Through Different Surgical Windows: Endoscopic Versus Transcranial

Surgically manageable lesions involving the intracranial or intracanalicular portions of the optic nerve (cranial nerve II) can be approached through several different operative windows. Given the complex anatomy of the optic nerve and its surrounding neurovascular structures, it is essential to understand the conventional and topographic anatomy of the optic nerve from different surgical perspectives as well as its relationship with surrounding structures. We describe the intracranial and intracanalicular course of the optic nerve and present an analytical evaluation of the degree of exposure provided by several different transcranial and endoscopic surgical approaches. Using 12 cadaveric specimens (24 sides), pterional, frontotemporal-orbital, supraorbital, unilateral subfrontal, and extended endonasal approaches were performed. The transcranial approaches were extended by removing the anterior clinoid process, unroofing the optic canal, and/or cutting the falciform ligament. The endonasal approach was extended using the transplanum transtuberculum, transmedial optic carotid recess, and transcanalicular modifications. The optic nerve was divided into proximal intracranial, distal intracranial, and intracanalicular segments, which were each divided coronally into quadrants and subquadrants, to evaluate their degree of exposure in each approach. The pterional approach provided 135° of exposure along the superolateral aspects of the entire intracranial optic nerve, and 225° of exposure of the intracanalicular optic nerve. The supraorbital and subfrontal approaches provided similar degrees of exposure, with 225°-270° of superolateral and superomedial exposure of the nerve along its intracranial and intracanalicular segments, depending on the approach extension used, with the subfrontal approach allowing for more medial control of the nerve. The endoscopic endonasal approach provided access to the inferior and medial quadrants of the optic nerve, allowing for 180° of exposure. Although the pterional approach provides the widest degree of surgical exposure of all optic nerve segments, the inferior and medial quadrants of the nerve can be adequately exposed only through an endoscopic endonasal approach. Optimal approach selection based on the intended target quadrant is essential for safe surgical exposure of the optic nerve.

Impact of the Intracranial Course of Internal Carotid Artery on Optimal Surgical Approach for Posterior Communicating Artery Aneurysms

The anterior temporal approach (ATA) has been reported as suitable for surgical clipping of posteriorly projecting internal carotid artery (ICA) aneurysms. As the ICA follows a variable course, tortuosity of the ICA may affect visualization of the aneurysm. The aim of this study was to investigate the impact of the intracranial course of the ICA and aneurysm projection on surgical approach. Consecutive patients with posterior communicating artery aneurysms treated with clipping at our hospital between May 2015 and April 2018 were retrospectively reviewed. When the transsylvian approach (TSA) could not achieve adequate exposure of the aneurysm, the ATA was subsequently performed. Distance between the ICA and the anterior and posterior clinoid line, angle between the midline and the C1 segment of the ICA, and aneurysm projection were compared between ATA and TSA groups. Of 52 patients (40 ruptured, 12 unruptured), 12 were in the ATA group, and 40 were in the TSA group. Mean ICA-anterior and posterior clinoid distance was significantly shorter in the ATA group than in the TSA group (P= 0.002), and mean midline-C1 angle was significantly larger in the ATA group than in the TSA group (P < 0.0001). The ATA group was associated with a greater frequency of posteriorly projecting aneurysms (12 of 12; 100%) than the TSA group (9 of 40; 22.5%) (P < 0.00001). A low-lying, laterally projecting intracranial ICA and posteriorly projecting aneurysm are predictors of the necessity for the ATA in the surgical clipping of posterior communicating artery aneurysms.

Variations of the 6th cranial nerve (nervus abducens) in the petroclival region: A microsurgical study

The aim of this study is to present the variations of nervus abducens in localization and number as it pierces the clival dura mater. The calvaria of 16 cadaveric heads were removed by making horizontal incisions from Glabella to Inion in both sides of the head. The dura mater was dissected. Cerebrum and cerebellum were taken out by obtuse dissection. Dissections of cavernous sinus were made under the stereomicroscope and the findings were photographed. Out of 16 specimens, one of them was excluded. Fifteen heads were bilaterally analyzed. Analysis of these nerves presented four different variations. Variation types a classified CN VI as a single trunk and entering a single dural pore with 77% occurrence. Variation type b classified CN VI with two branches running in the petroclival region and entering a single dural pore with 10% occurrence. Variation type c classified CN VI as 2 trunks and entering 2 separate but close dural pores with 10% occurrence. Variation type d classified CN VI with 2 distinct trunks and 2 branches entering 2 separate but close dural pores with 3% occurrence. CN VI plays a major role in the clinic of the eye. Due to its intracranial and extracranial course, injuries to the head and to the nerve may result in malfunctioning of the lateral muscles of the eye. Therefore, the variations of branching, relations and its course were analyzed.

Usefulness of Preoperative Simulation in Skull Base Approach: A Case Report.

Skull base approach is a neurosurgical challenge requiring dexterity of the operating surgeon for good postoperative outcome. In addition to the experience of the operating surgeon, adequate preoperative information of the tumor is necessary to ensure better outcome. In clinoid meningioma, it is sometimes difficult to determine its relationship with the surrounding structure and the feeding artery. Previously, preoperative simulation has been utilized to determine the intracranial course of the compressed nerves in relation to the petroclival meningioma. We report a case of clinoid meningioma where preoperative fusion of three dimensional computed tomography angiography (3D-CTA) and 3T-fast imaging employing steady-state acquisition (FIESTA) images was useful in determining the exact location of the feeding artery to devascularize the tumor and aid in surgery. Preoperative simulation with three-dimensional digital subtraction angiography (3D-DSA) and 3T-FIESTA fusion images can be a useful adjunct tool to supplement surgery and to train neurosurgical trainees.

Intracranial neoplastic lesions of the trigeminal nerve: How MRI can help

ObjectiveThe aim of this study was to highlight the role of MRI in detecting and diagnosing trigeminal nerve neoplastic lesions. Patients and methods56 patients included in our study presented with trigeminal symptoms with or without other neurological symptoms, subjected to conventional MRI sequences and 3D sequences as (CISS) and T1 magnetization-prepared rapid acquisition gradient echo (MP-RAGE). The inclusion criteria included patients with intracranial neoplastic lesions involving the trigeminal nerve and/or its branches. Results28 patients met our inclusions criteria and subjected to statistical analysis; 19 patients were females and 9 were males ranging between 15 and 70 years with a mean age of 47.5 years. 14 lesions were benign and 14 were malignant, and were distributed according to final diagnosis as meningiomas (10 cases), lymphoma (6 cases), deposits (4 cases), nasopharyngeal carcinoma (4 cases) schwannoma (3 cases), and neurofibroma (one case). The most frequent involved segments of the trigeminal nerve was simultaneous involvement of both Meckel’s cave and cavernous sinus in nine cases (32%). ConclusionsMRI is very helpful in demonstrating the whole intra-cranial course of the trigeminal nerve and in diagnosing various neoplastic lesions involving the nerve, and thus providing full roadmap before management.

The Hypoglossal Nerve: Anatomical Study of Its Entire Course.

Only a few anatomic studies of the entire course of the hypoglossal nerve (cranial nerve XII) have been reported. We analyzed all relationships of the 12th nerve with surrounding structures from the brainstem to the tongue through a microscopic perspective. A comprehensive anatomically and clinically oriented classification of its different segments is proposed. Ten formalin-fixed adult human cadaveric heads (20 sides) were dissected with the aim to explore the entire course of cranial nerve XII via lateral suboccipital, far lateral partial, or total transcondylar routes. Different segments of the nerve were identified based on the hypoglossal course and its relationship with surrounding structures. Measurements of every portion of the nerve were taken in all specimens during dissection. The hypoglossal nerve was divided into 5 segments: cisternal, intracanalar, descending, horizontal, and ascending. Detailed and comprehensive examination of basic anatomic relationships through the view of different transcranial and endoscope-assisted approaches was performed. A new perspective of the hypoglossal canal is proposed, and the venous plexus surrounding the intracanalar segment of the nerve is described in detail. Classification of 5 segments for the hypoglossal nerve seems anatomically valid, and it is surgically oriented with respect to all surgical approaches. Precise knowledge of the relationships with the surrounding structures may help to prevent some complications during surgery, and it is useful to explain, segment by segment, the pathogenic mechanisms for nerve injuries that are evidenced by lesions that exist along the entire intracranial and extracranial course.

Juan Valverde de Amusco (1525–1588): an eminent anatomist of the renaissance or a plagiarist of Vesalius? His work and its impact in renaissance anatomy

Introduction: The purpose of this study is to review and summarize the life and work of Juan Valverde de Amusco (1525–1588), his impact on the anatomy of the sixteenth century and focus on his controversy with Andreas Vesalius.Methods: A thorough search of the literature was undertaken in PubMed and Google Scholar as well as in history books through the internet and in History and Medical University libraries.Results: Valverde took almost directly from Andreas Vesalius 38 pictures. Occasionally, however, Valverde corrected Vesalius’ images, as in his depictions of the muscles of the eyes, nose and larynx.Conclusion: Valverde copied the work of Vesalius in many instances. Nevertheless, he had his fair share of contribution in the history of Anatomy; he managed to popularize and spread the new anatomy of the Rennaissance through his work which was far more cheaper than that of Vesalius; furthermore, his anatomic discoveries like the first depiction of the intracranial course of the carotid arteries (several decades before Willis’s description), the extrinsic ocular muscles and the middle ear bones contribute to the spirit of the Scientific Revolution.

Erratum to: Rapid progression of intracranial melanoma metastases controlled with combined BRAF/MEK inhibition after discontinuation of therapy: a clinical challenge.

Novel systemic therapies with anti-tumor activity in the brain including small molecules targeting BRAF and MEK, and immune checkpoint inhibition, offer the possibility of improved control of intracranial disease. A number of prospective trials support the judicious use of modern systemic therapies in patients with melanoma and limited brain metastases .The intracranial clinical course of patients who progress extracranially on BRAF/MEK inhibition remains poorly described in the literature. In this report, we highlight a series of clinical cases, with rapid progression of intracranial disease following discontinuation of dabrafenib/trametinib for extracranial disease progression or toxicity, a previously unreported finding in the medical literature with significant implications for patient care.

A simple post mortem room angiography method for the investigation of traumatic basal subarachnoid hemorrhage.

Identifying the site of vascular bleeding in fatal cases of traumatic basal subarachnoid hemorrhage (TBSAH) is important, but can be very difficult to achieve when there is extensive blood clot in the posterior cranial fossa. Post mortem angiography in these circumstances has been reported previously but with mixed results, and is rarely used in current practice within the United Kingdom. We have developed a simple and effective post mortem angiography method, using fluoroscopy and clear modern contrast medium, suitable for use in the autopsy room. Contrast medium was injected through an angiographic catheter positioned (with water filled balloon) in the extracranial vertebral artery (ECVA) just behind the clavicle, whilst the base of the skull and upper cervical spine area was visualized by fluoroscopy following digital subtraction of the bony images. The procedure was developed over a series of 8 TBSAH cases and using unfixed cadaveric specimens. A clear leak point was identified in 3 cases and the likely site indicated in a further fatality (all with tears subsequently confirmed by histology). In 4 cases, the bleeding point was not identified by angiography. In 7 deaths, the anatomy of the upper cervical loops and intracranial course of the vertebral arteries were well delineated by angiography and several small loop segments were documented. In 1 case, with severe degenerative vascular disease, extracranial vessel wall trauma and luminal thrombosis, angiography was unsuccessful above the level of the first cervical (C1) vertebra. Injecting contrast through the internal carotid artery, just above the bifurcation, was also shown to visualize the anterior cerebral circulation well. This method is likely to identify the main site of vascular tearing in about 50% of cases of TBSAH and to delineate the important anatomy of the vessels, prior to dissection of the upper neck and posterior fossa, thus minimizing handling artefacts and guiding the histological sampling of the vessels.