Neuroimaging in encephalitis: analysis of imaging findings and interobserver agreement.

AIM: To assess the role of imaging in the early management of encephalitis and the agreement on findings in a well-defined cohort of suspected encephalitis cases enrolled in the Prospective Aetiological Study of Encephalitis conducted by the Health Protection Agency (now incorporated into Public Health England). MATERIALS AND METHODS: Eighty-five CT examinations from 68 patients and 101 MRI examinations from 80 patients with suspected encephalitis were independently rated by three neuroradiologists blinded to patient and clinical details. The level of agreement on the interpretation of images was measured using the kappa statistic. The sensitivity, specificity, and negative and positive predictive values of CT and MRI for herpes simplex virus (HSV) encephalitis and acute disseminated encephalomyelitis (ADEM) were estimated. RESULTS: The kappa value for interobserver agreement on rating the scans as normal or abnormal was good (0.65) for CT and moderate (0.59) for MRI. Agreement for HSV encephalitis was very good for CT (0.87) and MRI (0.82), but only fair for ADEM (0.32 CT; 0.31 MRI). Similarly, the overall sensitivity of imaging for HSV encephalitis was ∼80% for both CT and MRI, whereas for ADEM it was 0% for CT and 20% for MRI. MRI specificity for HSV encephalitis between 3-10 days after symptom onset was 100%. CONCLUSION: There is a subjective component to scan interpretation that can have important implications for the clinical management of encephalitis cases. Neuroradiologists were good at diagnosing HSV encephalitis; however, agreement was worse for ADEM and other alternative aetiologies. Findings highlight the importance of a comprehensive and multidisciplinary approach to diagnosing the cause of encephalitis that takes into account individual clinical, microbiological, and radiological features of each patient.

The radiological diagnosis of frontotemporal dementia in everyday practice: an audit of reports, review of diagnostic criteria, and proposal for service improvement.

AIM: To investigate how commonly valuable diagnostic information regarding the frontotemporal dementias (FTDs) may be missed on routine radiological reporting. MATERIALS AND METHODS: The magnetic resonance imaging (MRI) examination results of a series of 39 consecutive patients in whom the diagnosis was initially thought to be a form of FTD were audited. Twenty-two patients satisfied formal diagnostic criteria for subtypes of FTD. The initial non-specialist radiological reports of the MRI examinations were compared with those of a radiologist who specifically examined the images for the possibility of atypical dementia. RESULTS: Six of the 22 original reports provided a full and accurate description of the radiological findings, while two provided a fully accurate interpretation. CONCLUSION: Valuable diagnostic information may be missed unless clinicians and radiologists jointly review and discuss brain imaging in cases of dementia. The use of standardised scales may enhance the reporting of MRI examinations for dementia.

Cavernous sinus thrombosis secondary to contralateral sphenoid sinusitis: a diagnostic challenge.

OBJECTIVE: To report what we believe to be the first case in the English language literature of unilateral cavernous sinus thrombosis complicating contralateral sphenoid sinusitis. CASE REPORT: A 62-year-old man presented to his general practitioner with a severe, right-sided, temporal headache. He was diagnosed with temporal arteritis and treated with systemic steroids. After five days, he developed right proptosis, ophthalmoplegia and ptosis. He was referred to the neurologists. After an urgent computed tomography head scan and computed tomography angiogram, a diagnosis of carotido-cavernous fistula was made. However, this was subsequently excluded after a negative cerebral angiogram. A review of the scans enabled diagnosis of right cavernous sinus thrombosis secondary to left sphenoiditis. The patient was referred to the otolaryngology team. After an urgent endoscopic sphenoidotomy and medical treatment, all symptoms and signs improved dramatically. CONCLUSIONS: Sphenoiditis can lead to contralateral cavernous sinus thrombosis. Urgent surgical sphenoidotomy, with appropriate medical treatment, can be successful in this life-threatening complication.

Retreatment of previously embolized cerebral aneurysms: the risk of further coil embolization does not negate the advantage of the initial embolization.

BACKGROUND AND PURPOSE: A significant minority of aneurysms treated by endovascular means undergo additional subsequent therapy to treat aneurysm recurrence. Our study was undertaken to determine the risk of additional coil embolization of aneurysms recurring following endovascular therapy. MATERIALS AND METHODS: Patients were identified during a 10-year period from prospectively collated data bases at 2 different neuroscience institutions. Patient outcome was obtained from the data bases or the patient's neurosurgical records. Occlusion grade was assessed at the time of treatment and at follow-up angiography as complete, near-complete, or incomplete. RESULTS: Of a total of 1834 aneurysms in 1631 patients, 100 aneurysms in 99 patients treated between January 1996 and December 2005 required additional coiling because of an enlarging remnant and subtotal occlusion. This comprised 6% of the patients treated and 8% of the total followed. Thromboembolic events complicated 3 retreatment procedures, but all 3 patients remain independent. Ninety-five patients were followed for 8-103 months (mean, 42.3 months) by conventional or MR angiography. CONCLUSION: Coil embolization of aneurysm recurrences has a low complication rate and leads to satisfactory occlusion in most cases. The risk from additional coil embolization does not negate the advantage of the initial embolization.

Atypical imaging appearances of intracranial meningiomas.

Meningiomas are the commonest primary, non-glial intracranial tumours. The diagnosis is often correctly predicted from characteristic imaging appearances. This paper presents some examples of atypical imaging appearances that may cause diagnostic confusion.

CT angiography of intracranial aneurysms related to arteriovenous malformations: a cautionary tale.

Computed tomographic angiography (CTA) has a high sensitivity and specificity for the detection of intracranial aneurysms and is increasingly used as the primary imaging modality in the investigation and pretreatment planning of patients presenting with acute subarachnoid haemorrhage. We present two cases in which CTA failed to demonstrate arteriovenous malformations associated with intracranial aneurysms.

Endovascular treatment of PICA aneurysms.

Endovascular treatment of aneurysms of the posterior inferior cerebellar artery (PICA) avoids manipulation of the brainstem or lower cranial nerves and should therefore carry a lower risk of neurological morbidity than surgical clipping. We reviewed our experience of 23 patients with PICA aneurysms treated by endovascular occlusion with Guglielmi detachable coils and documented their long-term outcome on follow-up. We observed a 28 day procedure-related neurological morbidity of 13% (3/23 patients). One patient suffered permanent neurological complications. There were no procedure-related deaths. None of our patients suffered a re-bleed from their treated aneurysms. Our series shows endovascular treatment of ruptured PICA aneurysms to be safe and effective.

Proton MR spectroscopy of cortical tubers in adults with tuberous sclerosis complex.

BACKGROUND AND PURPOSE: Significant advances have been made in understanding the origin of brain manifestations associated with tuberous sclerosis complex (TSC), most recently the idea that cortical tubers and subependymal nodules are a disorder of neocortical formation. The present study was designed to test the hypothesis that MR proton spectra of cortical tubers are abnormal because of the developmental immaturity of the tubers' neurons and glia. METHODS: Twenty-six adults with TSC were studied. Proton spectroscopy was performed with a single-voxel point-resolved spectroscopy technique in two 8-mL regions: one over a cortical tuber and the other over a corresponding anatomic area of normal-appearing brain in the contralateral cerebral hemisphere. The results were expressed in terms of the ratio of the area under the three prominent resonances of choline (Cho), creatine + phosphocreatine (Cr), and N-acetyl groups (NA). RESULTS: Cortical tubers showed statistically significantly lower NA/Cr (1.54 +/- 0.24 vs. 1.72 +/- 0.23), NA/(Cho+Cr) (0.80 +/- 0.14 vs. 0.91 +/- 0.12), and NA/Cho (1.69 +/- 0.36 vs. 1.97 +/- 0.38) than did normal-appearing brain. No statistically significant difference was found in the Cho/Cr ratios between the tubers and the contralateral brain (0.93 +/- 0.15 vs. 0.90 +/- 0.12). No lactate was identified in any cortical tubers. CONCLUSION: Proton spectroscopy can show differences between cortical tubers and normal-appearing white matter in patients with TSC. The reduced NA/Cr ratio is probably due to reduced levels of NA, most likely caused by the presence of immature neurons and glia in tubers that do not express NA, or by the presence of gliosis, a known histologic component of tubers.

Neurofibromatosis bright objects in children with neurofibromatosis type 1: a proliferative potential?

OBJECTIVES: The purpose of this study was to investigate the natural history of the high signal intensities shown on long TR sequences-neurofibromatosis type 1 bright objects (NBO)-in children with neurofibromatosis type 1 (NF1). We have paid particular attention to the development of tumors in these areas of abnormality. METHODS: During a 12-month period in 1992 to 1993, 46 children with clinically proven NF1 had a magnetic resonance (MR) examination at our institution. These were reviewed along with any previous or subsequent MR examinations that had been performed. We recorded the number, volume, and distribution of the abnormal high signal intensities and their change with time when serial examinations were performed. RESULTS: NBO were found in 93% of 46 children with NF1 on the original cross-sectional study. The most common anatomic sites were the globus pallidus (30.4%), cerebellum (23.5%), and midbrain (16.2%). The number and volume of NBO varied significantly with age. NBO were uncommon in children younger than 4 years but were very common and extensive between 4 to 10 years. A significant reduction in the number and volume of NBO was demonstrated in children older than 10 years as shown on both the cross-sectional and longitudinal portions of the study. Eight brain tumors (nonoptic pathway) were demonstrated in the 46 children (17%) with 1 child having two tumors. Only 1 child had symptoms referable to the tumor at the time of diagnosis. Five tumors developed in NBO that were documented on serial MR examinations. All those cases developed in children aged 7 to 12 years, and all these children had higher than average numbers and volumes of NBO. CONCLUSIONS: NBO occur commonly in children with NF1 and are most prevalent between the ages of 4 and 10. We have shown a high frequency of brain tumors in our children with NF1, but the majority of these were asymptomatic. We have demonstrated proliferative change NBO in 11% of 46 children. Most NBO regress with age and seem to be benign, however, young children with a large number and volume of NBO should be followed closely with regular MR examinations because of an increased risk of proliferative change. neurofibromatosis type 1, magnetic resonance, tumor, astrocytoma, childhood.

Neurofibromatosis type 1: the role of neuroradiology.

Neurofibromatosis type 1 is the commonest of the phakomatoses with a prevalence of 1 in 3-4000. In common with most of the other phakomatoses it is a genetic disorder with typical dermatological manifestations. Many organ systems can be affected but brain, spine, cranial nerve and peripheral nerve involvement is frequent. In this review we will describe the central nervous system manifestations of neurofibromatosis type 1 and discuss some of the controversies raised by investigating children with this disorder.