Skull Base Chordoma and Chondrosarcoma: Neuroradiologist's Guide to Diagnosis, Surgical Management, and Proton Beam Therapy.

Skull base chordomas and chondrosarcomas are distinct types of rare, locally aggressive mesenchymal tumors that share key principles of imaging investigation and multidisciplinary care. Maximal safe surgical resection is the treatment choice for each, often via an expanded endoscopic endonasal approach, with or without multilayer skull base repair. Postoperative adjuvant radiation therapy is frequently administered, usually with particle therapy such as proton beam therapy (PBT). Compared with photon therapy, PBT enables dose escalation while limiting damage to dose-limiting neurologic structures, particularly the brainstem and optic apparatus, due to energy deposition being delivered at a high maximum with a rapid decrease at the end of the penetration range (Bragg peak phenomenon). Essential requirements for PBT following gross total or maximal safe resection are tissue diagnosis, minimal residual tumor after resection, and adequate clearance from PBT dose-limiting structures. The radiologist should understand surgical approaches and surgical techniques, including multilayer skull base repair, and be aware of evolution of postsurgical imaging appearances over time. Accurate radiologic review of all relevant preoperative imaging examinations and of intraoperative and postoperative MRI examinations plays a key role in management. The radiology report should reflect what the skull base surgeon and radiation oncologist need to know, including distance between the tumor and PBT dose-limiting structures, tumor sites that may be difficult to access via the endoscopic endonasal route, the relationship between intradural tumor and neurovascular structures, and tumor sites with implications for postresection stability. ©RSNA, 2024 Supplemental material is available for this article.

A case of a spontaneous intraorbital arteriovenous fistula: clinico-radiological findings and treatment by transvenous embolisation via the superior ophthalmic vein.

A 72-year-old male presented with progressive right axial proptosis and red eye. Catheter angiography demonstrated an intraorbital arteriovenous fistula (IAVF) distal to the central retinal artery (CRA). Transvenous embolisation following direct surgical exposure of the superior ophthalmic vein (SOV) resulted in rapid resolution of his symptoms and signs. Transvenous embolisation via the SOV is a safe, effective alternative to transarterial embolisation for treating spontaneous IAVF where transarterial embolisation poses a risk of CRA occlusion.

Haemorrhagic synovial cyst presenting as thoracic cord compression: a case report and review of the literature.

Synovial cysts are often incidental findings on spinal imaging. They can present with back pain and radicular symptoms; rarely, they can rupture causing an epidural haematoma and thecal sac compression. We present the first reported case of a haemorrhagic synovial cyst causing thoracic cord compression, and review the pertinent literature.

Pituitary adenoma and incidental superior hypophyseal aneurysm.

In patients with pituitary adenomas, intra-cranial aneurysms can be an incidental finding, and are usually located outside the pituitary region. The authors describe the multi-modal management of a rare case of an aneurysm of the supraclinoid carotid that encroached into a pituitary macroadenoma.

Endovascular coiling in the treatment of patients with renal artery aneurysms.

Endovascular coiling is a percutaneous endovascular technique used in the management of arterial aneurysms with high success rates and minimal associated morbidity. We present a series of three patients with incidental renal artery aneurysms treated successfully with endovascular coiling, despite comorbidities. One patient had an aneurysm associated with a solitary kidney. The decision to use this technique becomes critical when the aneurysm involves a single functioning kidney. Each renal artery aneurysm was successfully coiled by combining vascular and neurointerventional techniques. The results from the present case series also highlight the challenges faced in therapeutic decision-making in complex situations with limited error margins.

Tumefactive demyelination-an unusual neurological presentation of HIV.

We describe 3 individuals infected with human immunodeficiency virus with unusual focal brain syndromes; magnetic resonance imaging revealed "open-ring" pattern space occupying lesions. After deterioration while the patients were receiving anti-Toxoplasma therapy, brain biopsy was performed, which revealed aggressive demyelination consistent with tumefactive demyelination. Treatment with high-dose steroids resulted in complete recovery in all cases.

Incidental finding of fenestration of the supraclinoid internal carotid artery with appearances on magnetic resonance angiography.

A case of incidentally diagnosed fenestration of the supraclinoid internal carotid artery (ICA) with an associated aneurysm is presented. We present appearances on magnetic resonance angiography, which have not been previously described. Careful interrogation of the data in volume-rendered and multiplanar reformats was required to make the diagnosis. The relationship between fenestrations and aneurysms in the anterior circulation is discussed both in general terms and with specific regard to the supraclinoid ICA. We also review the embryology of the distal ICA, which may help explain the adult anatomy of this rare lesion as a failure of caudal separation of the rostral and caudal divisions of the primitive distal ICA.

Traumatic clival subdural hematoma in an adult.

Retroclival hematomas are a rare entity. They are usually associated with significant trauma, and patients frequently have focal neurological deficits, especially cranial nerve palsies. Previous case reports of epidural clival hematomas have been described almost exclusively in the pediatric population. The authors report a unique case of traumatic clival subdural hematoma, which has never been described in an adult except in the context of hemophilia. An 18-year-old man presented with continuing nausea and headaches following a seemingly trivial head injury. He was found to have a posterior fossa retroclival hematoma extending into the spinal subdural space but without any neurological deficits. He was treated conservatively, with a good outcome. The authors discuss the possible mechanisms of injury, management, and complications related to this rare condition, and they review the pertinent literature.

Visual field deficit due to downward displacement of optic chiasm.

Visual disturbance in hydrocephalus is typically due to raised intracranial pressure. We describe a patient who presented with marked loss of peripheral visual fields, but without features suggestive of raised intracranial pressure. MR scan showed an enlarged third ventricle and a downward displacement of the optic chiasm, Chiari II malformation. These radiological changes and the visual field deficits reversed after endoscopic third ventriculostomy and foramen magnum decompression. These observations support the view that the treatment of the hydrocephalus in such patients can help to reverse the change in the position of the optic chiasm and the visual field deficits.

Pneumococcal meningitis secondary to intra-sphenoidal encephalocoele.

Basal encephalocoeles are rare congenital abnormalities of the skull base. The authors describe a rare case of spontaneous CSF leak and meningitis secondary to an intra-sphenoidal encephalocoele. Initial endoscopic transsphenoidal repair was unsuccessful, necessitating a combined subtemporal and transsphenoidal approach to close the defect.

Double origin of the posterior inferior cerebellar artery with findings on conventional and CT angiography.

A case of double origin of the posterior inferior cerebellar artery (PICA) is presented, with appearances on both cross-sectional imaging and conventional angiography. An associated aneurysm was found, strengthening the belief that this variation is associated with intracranial aneurysms. Furthermore, this is the first report of a right-sided double-origin PICA in a female patient, which calls into question the previously proposed male and left-sided preponderance of this variation.

Posterior Inferior Cerebellar Artery/Vertebral Artery Subarachnoid Hemorrhage: A Comparison of Saccular vs Dissecting Aneurysms.

BACKGROUND: Two distinct categories of aneurysms are described in relation to the posterior inferior cerebellar artery (PICA) and vertebral artery (VA): saccular (SA) and dissecting (DA) types. This distinction is often unrecognized because abnormalities here are uncommon and most studies are small. OBJECTIVE: To determine if there are any differences in the clinical presentation, in-hospital course, or outcomes in patients with DA vs SA of the PICA or VA. METHODS: Thirty-eight patients with a VA or PICA aneurysm were identified from a departmental subarachnoid hemorrhage database and categorized into DA or SA types. Prospectively collected demographic and outcome data (length of stay, discharge Glasgow Outcome Score) were supplemented by abstracting records for procedural data (extraventricular drain [EVD], ventriculoperitoneal [VP] shunt, tracheostomy, and nasogastric feeding). Univariate, binary logistic regression, and Cox regression analysis was used to compare patients with SA vs DA. RESULTS: Three aneurysms related to arteriovenous malformation were excluded. Five patients were conservatively managed. Of the 30 treated cases, more patients with a DA presented in poor grade (6/13 vs 2/17 SA; P = .035). More DA patients required an EVD (85% vs 29%; P = .003), VP shunt (54% vs 6%; P = .003), tracheostomy (46% vs 6%; P < .01), and nasogastric feeding (85% vs 35%; P = .007). The median length of stay (41 vs 17 d, P < .001) was longer, and the age and injury severity adjusted odds of discharge home were significantly lower in the DA group (P = .008). Thirty-day mortality was not significantly different (23% of DA vs 24% of SA; P = .2). CONCLUSION: The presentation, clinical course, and outcomes differ in patients with DA vs SA of the PICA and VA.

Varicella zoster virus cerebral aneurysmal vasculopathy presenting in a newly-diagnosed HIV-positive patient.

We report the case of a newly-diagnosed HIV-positive patient with varicella zoster virus aneurysmal vasculopathy confirmed on intrathecal antibody testing, despite a negative Cerebrospinal fluid (CSF) Varicella Zoster Virus (VZV) Polymerase Chain Reaction (PCR). This highlights the importance of prompt treatment with antiviral and steroid therapy in the presence of clinical or radiological suspicion whilst awaiting further confirmatory testing.

Neurogenic pulmonary oedema complicating a lateral medullary infarct.

Neurogenic pulmonary oedema (NPO) is a rare clinical syndrome of pulmonary oedema occurring secondary to an insult of the central nervous system (CNS). The exact aetiology of this disorder is unknown. NPO can be fatal and poor awareness and identification of this entity, particularly in terms of misdiagnosis as primary pulmonary or cardiac disease, can result in suboptimal management and outcomes. We describe the presentation and management of a 68-year-old woman with an acute left lateral medullary stroke complicated by pulmonary oedema. The likely aetiology is discussed, and important learning points are highlighted.

A Confirmed Case in the United Kingdom of Hirayama Disease in a Young White Male Presenting with Hand Weakness.

BACKGROUND: We present the first reported case of Hirayama disease in the United Kingdom. A literature review of Hirayama disease in the Western literature shows that this case is unique in being the first in the United Kingdom, constituting one of only a few cases in Europe with supporting magnetic resonance imaging and reported treatment outcome. CASE DESCRIPTION: Our patient was a young Caucasian male who presented with progressive bilateral hand weakness, had confirmatory magnetic resonance imaging findings of Hirayama disease, and experienced improvement of symptoms with cervical collar immobilization. CONCLUSIONS: This case lends further evidence to the flexion-induced myelopathy theory of Hirayama disease and supports the findings of other studies in which avoidance of neck flexion and cervical immobilization helped to attenuate disease progression in this patient group.

Use of intraoperative Doppler ultrasound with neuronavigation to guide arteriovenous malformation resection: a pediatric case series.

OBJECT: Over the last 20 years, several intraoperative adjuncts, including ultrasonography, neuronavigation, and angiography, have been said to aid the intraoperative localization and resection of cerebral arteriovenous malformations (AVMs). The authors assessed the value of intraoperative Doppler ultrasonography in conjunction with neuronavigation during surgery for cerebral AVMs in the pediatric population. METHODS: The authors reviewed all cranial AVM resections performed by a single surgeon at their institution in the period from 2007 to 2013 and here describe their experience and results in a series of 20 consecutive AVM resections in 19 pediatric patients. Intraoperative Doppler ultrasonography had been used in conjunction with preoperative CT or neuronavigational MRI. Preoperative and postoperative clinical findings, patient age, and Spetzler-Martin AVM grade were identified in all patients. RESULTS: All patients, whose ages ranged from 2 to 16 years, underwent craniotomy and excision of an AVM, which was supratentorial in 18 cases and infratentorial in 2. Patients in 11 cases underwent preoperative embolization, and all other patients underwent cerebral angiography prior to surgery, except for 2 patients who were urgently surgically treated because of low Glasgow Coma Scale scores and associated hematoma. Spetzler-Martin Grades I (3 cases), II (6), III (7), and IV (4) AVMs were represented in this series. Intraoperative Doppler ultrasound provided high-quality images in all cases and demonstrated the location, size, and flow characteristics of the AVM and any associated hematoma. Delayed postoperative cerebral angiography demonstrated successful AVM resection in all cases. An assessment of clinical outcomes revealed no new long-term neurological deficits at 3 months postoperatively. CONCLUSIONS: Intraoperative Doppler ultrasonography is a reliable and useful tool for intraoperative localization and guidance for AVM resection in the pediatric population. When used in conjunction with neuronavigation equipment and modern microscopes, this technique has shown a very high complete resection rate with extremely low associated morbidity.

Using Bayesian tissue classification to improve the accuracy of vestibular schwannoma volume and growth measurement.

BACKGROUND AND PURPOSE: True 3D measurements of tumor volume are time-consuming and subject to errors that are particularly pronounced in cases of small tumors. These problems complicate the routine clinical assessment of tumor growth rates. We examined the accuracy of currently available methods of size and growth measurement of vestibular schwannomas compared with that of a novel fast partial volume tissue classification algorithm. METHODS: Sixty-three patients with unilateral sporadic vestibular schwannomas underwent imaging. Thirty-eight of these patients underwent imaging two or more times at approximately 12-month intervals. Contrast-enhanced 3D T1-weighted images were used for all measurements. An experienced radiologist performed standard size estimations, including maximal diameter, elliptical area, perimeter, manually segmented area, intensity thresholded seeding volume, and manually segmented volume. A method for calculating volume was also used, incorporating Bayesian probability statistics to estimate partial volume effects. Manually segmented volume was obtained as a baseline standard measure. A computer-generated phantom exhibiting the intensity and partial volume characteristics of brain tissue, CSF, and intracanalicular vestibular schwannoma tissue was used to measure absolute accuracy of the standard technique and Bayesian partial volume segmentation. RESULTS: The Bayesian partial volume segmentation method showed the highest correlation (R(2) = 0.994) with the standard method, whereas the commonly used method of maximal diameter measurement showed poor correlation (R(2) = 0.732). Accuracy of Bayesian segmentation was shown to be more than twice that of manual segmentation, with an absolute accuracy of 5% (cf, 13%) and a remeasurement accuracy of 70 mm(3) (cf, 150 mm(3)). For the 38 patients who underwent imaging twice, definite tumor growth was shown for 12, potential growth for seven, no growth for 17, and definite shrinkage for two. CONCLUSION: Commonly used methods such as maximal diameter measurements do not provide adequate statistical accuracy with which to monitor tumor growth in patients with small vestibular schwannomas. Bayesian partial volume segmentation provides a more accurate and rapid method of volume and growth estimation. These differences in measurement accuracy translated into a significant improvement in clinical assessment, allowing identification of tumor growth in 10 of 12 cases that appeared to be static in size when manual segmentation techniques are used. The technique is quick to perform and suitable for use in routine clinical practice.