Trans-sulcal parafascicular approach to subcortical lesions.

Historically, neoplasms which are located in the subcortical region of the brain are considered technically difficult to access. As such, tumours in these locations are usually avoided, due to the risks associated with traversing eloquent cortex, the disrupting of white matter tracts, or the need to use narrow corridors to approach the lesion. Tubular retractors are able to gently displace brain parenchyma and white matter in an atraumatic fashion to access these deep regions. We demonstrate a minimally invasive trans-sulcal parafascicular approach using the Brainpath system (NICO Corp, Indianapolis, Indiana) to a caudate head metastasis as a representative case.

MR regional perfusion imaging: visualizing functional collateral circulation.

SUMMARY: We applied regional perfusion imaging (RPI), a new arterial spin-labeling MR imaging method that selectively studies regions of the brain perfused by individual carotid and basilar arteries. In a patient with cerebrovascular disease, RPI showed cerebral tissue perfused by pial collateral vessels, thereby demonstrating the relationship between anatomic and functional information, which was lacking in conventional x-ray angiography. RPI may be useful to study functional collateral circulation and hence guide therapy in ischemic disease.

Endolymphatic sac tumour: a rare cause of recurrent vertigo.

Endolymphatic sac tumour occurring in a 32-year-old man presenting with Meniere's like symptoms of recurrent vertigo, hearing loss and tinnitus is described. Magnetic resonance imaging and computed tomography showed a vascular bone tumour centred over the retrolabyrinthine aspect of the temporal bone where the endolymphatic sac was located. Surgical excision via a translabyrinthine approach was performed. Endolymphatic sac tumours are rare papillary adenocarcinomas that arise from the endolympatic sac. It can be mistaken both on radiology and histology for other tumours such as paragangliomas, renal or papillary thyroid carcinoma metastases. Surgical excision is the treatment of choice but sacrifice of the auditory and facial nerve may be needed in advanced cases to achieve tumour clearance.

Improved neuronal transgene expression from an AAV-2 vector with a hybrid CMV enhancer/PDGF-beta promoter.

BACKGROUND: Adeno-associated virus type 2 (AAV-2) vectors are highly promising tools for gene therapy of neurological disorders. After accommodating a cellular promoter, AAV-2 vectors are able to drive sustained expression of transgene in the brain. This study aimed to develop AAV-2 vectors that also facilitate a high level of neuronal expression by enhancing the strength of a neuron-specific promoter, the human platelet-derived growth factor beta-chain (PDGF) promoter. METHODS AND RESULTS: A hybrid promoter approach was adopted to fuse the enhancer of human cytomegalovirus immediately early (CMV) promoter to the PDGF promoter. In cultured cortex neurons, AAV-2 vectors containing the hybrid promoter augmented transgene expression up to 20-fold over that mediated by titer-matched AAV-2 vectors with the PDGF promoter alone and 4-fold over the CMV enhancer/promoter. Injection of AAV-2 vectors with the hybrid promoter into the rat striatum resulted in neuron-specific transgene expression, the level of which was about 10-fold higher than those provided by the two control AAV-2 expression cassettes at 4 weeks post-injection and maintained for at least 12 weeks. Gene expression in the substantia nigra through possible retrograde transport of the AAV-2 vectors injected into the striatum was not obvious. After direct injection of AAV-2 vectors into the substantia nigra, transgene expression driven by the hybrid promoter was observed specifically in dopaminergic neurons and its level was about 3 and 17 times higher than that provided by the PDGF promoter alone and the CMV enhancer/promoter, respectively. CONCLUSIONS: Enhanced transgene capacity plus neuron-specificity of the AAV-2 vectors developed in this study might prove valuable for gene therapy of Parkinson's disease.