Imaging assessment of traumatic brain injury.

Traumatic brain injury (TBI) constitutes injury that occurs to the brain as a result of trauma. It should be appreciated as a heterogeneous, dynamic pathophysiological process that starts from the moment of impact and continues over time with sequelae potentially seen many years after the initial event. Primary traumatic brain lesions that may occur at the moment of impact include contusions, haematomas, parenchymal fractures and diffuse axonal injury. The presence of extra-axial intracranial lesions such as epidural and subdural haematomas and subarachnoid haemorrhage must be anticipated as they may contribute greatly to secondary brain insult by provoking brain herniation syndromes, cranial nerve deficits, oedema and ischaemia and infarction. Imaging is fundamental to the management of patients with TBI. CT remains the imaging modality of choice for initial assessment due to its ease of access, rapid acquisition and for its sensitivity for detection of acute haemorrhagic lesions for surgical intervention. MRI is typically reserved for the detection of lesions that may explain clinical symptoms that remain unresolved despite initial CT. This is especially apparent in the setting of diffuse axonal injury, which is poorly discerned on CT. Use of particular MRI sequences may increase the sensitivity of detecting such lesions: diffusion-weighted imaging defining acute infarction, susceptibility-weighted imaging affording exquisite data on microhaemorrhage. Additional advanced MRI techniques such as diffusion tensor imaging and functional MRI may provide important information regarding coexistent structural and functional brain damage. Gaining robust prognostic information for patients following TBI remains a challenge. Advanced MRI sequences are showing potential for biomarkers of disease, but this largely remains at the research level. Various global collaborative research groups have been established in an effort to combine imaging data with clinical and epidemiological information to provide much needed evidence for improvement in the characterisation and classification of TBI and in the identity of the most effective clinical care for this patient cohort. However, analysis of collaborative imaging data is challenging: the diverse spectrum of image acquisition and postprocessing limits reproducibility, and there is a requirement for a robust quality assurance initiative. Future clinical use of advanced neuroimaging should ensure standardised approaches to image acquisition and analysis, which can be used at the individual level, with the expectation that future neuroimaging advances, personalised to the patient, may improve prognostic accuracy and facilitate the development of new therapies.

A retrospective analysis of revision endoscopic third ventriculostomy.

PURPOSE: Endoscopic third ventriculostomy (ETV) has gained favour as an effective treatment for obstructive hydrocephalus. However, the timing of ETV failure and the long-term efficacy of revision ETV remain poorly documented. METHODS: A retrospective review was performed of patients undergoing revision ETV between 1999 and 2007. Only those patients in whom there was evidence of a good sustained clinical improvement after the initial ETV were considered candidates for ETV revision. All other patients underwent insertion of a ventriculoperitoneal shunt at the time of ETV failure. Failures that were selected for repeat ETV were subdivided into; "early" if the revision occurred within the first 3 months of the primary procedure and "late" if occurring after this. RESULTS: Ten patients underwent revision ETV (6% of all ETVs performed). Age ranged from 2 months to 32 years (mean 13.6 years). Three "early" revision ETV were performed at a mean of 1.3 months, and there were seven "late" revisions performed at a mean of 27 months. The stoma was closed in seven patients and narrowed in one patient, and a second membrane was found under the original patent stoma in a further two patients. In two patients, a third ETV procedure was performed (both at 1 month after second ETV), and the stoma was closed in both these patients. No patients have required a shunt. CONCLUSION: At last follow-up (mean 38 months), all patients remain well. Revision ETV appears a safe and effective means of managing hydrocephalus-providing there is clinical evidence that the primary procedure was initially effective. It is important to emphasise that patients with an initially successful ETV are by no means "cured".