Roger D. Laitt

Cystic optic nerve meningioma presenting with acute proptosis.

A 37-year-old woman presented with acute left-sided proptosis. Magnetic resonance imaging demonstrated a solid intraconal mass lesion with an associated ‘capping’ cyst. This lesion was resected and found on histological examination to be an optic nerve sheath meningioma. Small perineural cysts have been reported with optic nerve sheath meningioma but we believe this to be the first reported case of a large peritumoral cyst associated with this type of mass lesion. We speculate on the aetiology of the cyst and the associated acute proptosis.

How much can be concluded from ISAT

The Editorial submission by Tait et al. attempts to give a perspective on ISAT almost 5 years following trial closure. It unfortunately adds no new scientifically sound information to the debate about the management of aneurysmal subarachnoid haemorrhage, which has been previously rehearsed in a large number of editorials and comments in mainstream journals. – 9 ISAT was a randomised controlled trial (RCT) designed to compare a neurosurgical and endovascular treatment policy using clipping or coiling, and therefore did not just compare the two treatment procedures. It was a pragmatic trial and reflected management of aneurysmal subarachnoid haemorrhage in participating centres during the trial period. It meets published guidelines on RCTs, which are poorly understood by most clinicians. The published results clearly demonstrate an advantage of coiling over clipping in the study population and have produced a dramatic change in management of aneurysmal SAH with some centres reporting a coiling rate of over 90%. The authors correctly identified the main data pertaining to ISAT recruitment; however, they fail to mention that the patients randomised into ISAT represent a selected subgroup with characteristics thought to represent a good chance of neurological outcome following surgical clipping. The fact that there was better outcome for coiling in this subgroup is therefore important. Given that so many patients were deemed ineligible for entry, one is unable to generalize the results to the entire population and application to practice must be limited to those whose characteristics match those randomised in ISAT alone. This has been clearly recognised by ISAT authors. Many management decisions, therefore, still rely on data from observational studies. These studies claim better outcomes for coiling in posterior circulation aneurysms, aneurysms in older patients and in patients in poorer grade when compared with clipped controls. There is also pressure from the patient for less invasive surgery. It is therefore understandable that increasing numbers of aneurysms are being treated in this way. The potential for aneurysm recurrence and rebleeding following coiling is of concern, and because of this coiled aneurysms undergo rigorous imaging follow-up in most centres. Clipped aneurysms have never been subject to the same rigorous follow up despite the fact that clipped aneurysms do rebleed. In ISAT there is no significant difference between rebleeding rates in the clipped and coiled groups at 1 year. There is, however, a difference between rebleeds in these groups prior to treatment with a difference in time to primary treatment of 1.7 and 1.1 days, respectively. This fact is important and does not weaken the study, which is comparing a treatment policy. Indeed, it is an important observation as delays in treatment may relate to lack of resource and this should therefore remain in the analysis. Some surgeons still prefer to delay clipping in certain clinical situations, for example, in the presence of severe vasospasm. This may not be a problem with coiling. Also with vascular neurosurgical subspecialisation there are decreasing numbers of surgeons available to clip. This may have had a further effect on timing of neurosurgical interventions. The authors correctly state that the functional improvement in patients between 2 and 12 months is more pronounced in the clipped group with a 2.6% reduction in number of dead and dependent in the coiled group compared with 6% reduction in the clipped group. This is almost certainly due to slower recovery rates in clipped patients and will therefore not be sustainable. There is no evidence that this is due to rebleeding in the coiled group and data about

Demonstration of cerebral perfusion abnormalities in moyamoya disease using susceptibility perfusion- and diffusion-weighted MRI

Abstract We describe the use of diffusion-weighted imaging and perfusion MRI using a contrast-medium bolus in the preoperative investigation for young man presenting with a cerebral ischaemic episode as a manifestation of moyamoya disease.

A Case of a Spontaneous Intraorbital Arteriovenous Fistula: Clinico-Radiological Findings and Treatment by Transvenous Embolisation via the Superior Ophthalmic Vein

Abstract 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.

Use of single-slice thick slab phase-contrast angiography for the diagnosis of dural venous sinus thrombosis

Abstract. The aim of this study was to examine the reliability of single-slice phase-contrast angiography (SSPCA) as a rapid technique for the investigation of suspected dural venous sinus occlusion. Images were obtained on 25 normal volunteers to document the accuracy of SSPCA in the demonstration of slow flow states. Normal volunteers were imaged using sagittal and coronal SSPCA (slice thickness 13 cm, matrix 256 × 256, TR 14 ms, TE 7 ms, flip angle 20 °, peak velocity encoding rate 30 cm/s). Sinus patency and flow rate were confirmed by measurement of flow in the superior sagittal and transverse sinuses using quantified single-slice phase difference images. Imaging was performed in 50 patients undergoing routine brain scans in order to determine the optimal slice orientation for clinical use. Twenty-one patients with suspected dural venous sinus thrombosis were also investigated with SSPCA and the diagnosis confirmed by one or more alternative imaging techniques. Imaging time was 29 s per acquisition and image quality was good in all cases. Variations in dural sinus patency and flow in normal volunteers were accurately predicted by SSPCA (kappa = 0.92). Use of a single angulated slice (130 mm thick, para-sagittal image angled 30 ° towards coronal and 30 ° towards transverse) provided sufficient separation of right- and left-sided venous structures to allow use of a single projection. The presence and extent of sinus occlusions in 14 patients and the absence of thrombosis in 7 were accurately identified by SSPCA. Sensitivity and specificity in this limited study were both 100 %. The SSPCA technique takes less than 30 s and provides a reliable and rapid technique for the diagnosis of dural venous sinus thrombosis.

The influence of chemical shift artifact on magnetic resonance imaging of the ligamentum flavum at 0.5 tesla

Study Design Retrospective clinical magnetic resonance imaging study and prospective magnetic resonance imaging volunteer study of the appearance of the ligamentum flavum. Objective To demonstrate the effect of chemical shift artifact on the apparent thickness of the ligamentum flavum on axial magnetic resonance images. Summary of Background Data The ligamentum flavum is a symmetric structure clearly seen on magnetic resonance images. Apparent unilateral thickening may be interpreted as indicating a pathologic process, and the influence of chemical shift artifact on the apparent thickness of the ligamentum flavum has not been emphasized. Methods Ligamenta flava thicknesses were measured from axial T1-weighted gradient echo magnetic resonance scans of 12 consecutive patients and various axial sequences in seven volunteers. Results The ligamentum flavum appeared consistently thicker on the lower side of the readout gradient field. This chemical shift effect could be manipulated by swapping phase and frequency or patient orientation in the magnet. Conclusions Caution should be applied in attributing apparent asymmetry of the ligamenta flava to disease; the influence of chemical shift artifact should be considered.

Time of Flight 3D Magnetic Resonance Angiography in the Follow-up of Coiled Cerebral Aneurysms

The use of Guglielmi Detachable Coil (CDC) for the endovascular treatment of intracerebral aneurysms is increasing, particularly in those aneurysms for which there is a high surgical morbidity and mortality. However, the long-term efficacy of GDC is not known. Until the natural history of GDC treatment is established long-term follow-up in this cohort of patients is required, of necessity involving repeated intraarterial angiography (IA DSA) with its known attendant risks and exposure to ionising radiation. Three dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) is now readily accepted as a non-invasive screening tool for familial aneurysmal disease and has been used as an alternative to IA DSA in the surgical management of aneurysmal subarachnoid haemorrhage. MRA in patients treated with GDC is safe, imparts no radiation dose and provides acceptable image quality. The aim of this study was to assess 3D TOP MRA source data, maximum intensity projection (MIP) and 3D isosurface reconstruction in comparison to IA DSA in the follow-up of 25 patients treated with GDC. Images were assessed for parent and branch artery flow, the presence of neck recurrence and aneurysm regrowth. There was good correlation for all these features when 3D isosurface MRA and source data were compared with IA DSA. The correlation between MIP MRA and IA DSA was less robust. Additional confidence can be obtained by performing plain films of the skull to demonstrate change in coil ball configuration. MRA has the potential to replace IA DSA in the follow-up of GDC treated cerebral aneurysms.

Schwannomatosis: a genetic and epidemiological study

Objectives Schwannomatosis is a dominantly inherited condition predisposing to schwannomas of mainly spinal and peripheral nerves with some diagnostic overlap with neurofibromatosis-2 (NF2), but the underlying epidemiology is poorly understood. We present the birth incidence and prevalence allowing for overlap with NF2. Methods Schwannomatosis and NF2 cases were ascertained from the Manchester region of England (population=4.8 million) and from across the UK. Point prevalence and birth incidence were calculated from regional birth statistics. Genetic analysis was also performed on NF2, LZTR1 and SMARCB1 on blood and tumour DNA samples when available. Results Regional prevalence for schwannomatosis and NF2 were 1 in 126 315 and 50 500, respectively, with calculated birth incidences of 1 in 68 956 and 1 in 27 956. Mosaic NF2 causes a substantial overlap with schwannomatosis resulting in the misdiagnosis of at least 9% of schwannomatosis cases. LZTR1-associated schwannomatosis also causes a small number of cases that are misdiagnosed with NF2 (1%–2%), due to the occurrence of a unilateral vestibular schwannoma. Patients with schwannomatosis had lower numbers of non-vestibular cranial schwannomas, but more peripheral and spinal nerve schwannomas with pain as a predominant presenting symptom. Life expectancy was significantly better in schwannomatosis (mean age at death 76.9) compared with NF2 (mean age at death 66.2; p=0.004). Conclusions Within the highly ascertained North-West England population, schwannomatosis has less than half the birth incidence and prevalence of NF2.

Familial unilateral vestibular schwannoma is rarely caused by inherited variants in the NF 2 gene: Familial Unilateral Vestibular Schwannoma

Unilateral vestibular schwannoma (VS) occurs with a lifetime risk of around 1 in 1,000 and is due to inactivation of the NF2 gene, either somatically or from a constitutional mutation. It has been postulated that familial occurrence of unilateral VS occurs more frequently than by chance, but no causal mechanism has been confirmed.

Bisphosphonate-induced Osteonecrosis of the Maxilla Presenting as a Cicatricial Ectropion

Abstract Case Report: A 63-year-old gentleman, who was being treated with bisphosphonates for multiple myeloma, presented with a cicatricial ectropion of the lower eyelid, without exposure keratopathy. A CT scan demonstrated extensive destruction of bone with an infraorbital fracture surrounded by sclerotic bony changes. The patient was managed conservatively with discontinuation of bisphosphonate therapy and topical ocular lubricants. The patients condition remained unchanged a year after this initial management.