SUMMARY: Spinal dural arteriovenous (AV) fistulas are the most commonly encountered vascular malformation of the spinal cord and a treatable cause for progressive para- or tetraplegia. They most commonly affect elderly men and are classically found in the thoracolumbar region. The AV shunt is located inside the dura mater close to the spinal nerve root where the arterial blood from a radiculomeningeal artery enters a radicular vein. The increase in spinal venous pressure leads to decreased drainage of normal spinal veins, venous congestion, and the clinical findings of progressive myelopathy. On MR imaging, the combination of cord edema, perimedullary dilated vessels, and cord enhancement is characteristic. Therapy has to be aimed at occluding the shunting zone, either by superselective embolization with a liquid embolic agent or by a neurosurgical approach. Following occlusion of the fistula, the progression of the disease can be stopped and improvement of symptoms is typically observed.

SUMMARY: Transarterial embolization in the external carotid artery (ECA) territory has a major role in the endovascular management of epistaxis, skull base tumors, and dural arteriovenous fistulas. Knowledge of the potential anastomotic routes, identification of the cranial nerve supply from the ECA, and the proper choice of embolic material are crucial to help the interventionalist avoid neurologic complications during the procedure. Three regions along the skull base constitute potential anastomotic routes between the extracranial and intracranial arteries: the orbital, the petrocavernous, and the upper cervical regions. Branches of the internal maxillary artery have anastomoses with the ophthalmic artery and petrocavernous internal carotid artery (ICA), whereas the branches of the ascending pharyngeal artery are connected to the petrocavernous ICA. Branches of both the ascending pharyngeal artery and the occipital artery have anastomoses with the vertebral artery. To avoid cranial nerve palsy, one must have knowledge of the supply to the lower cranial nerves: The petrous branch of the middle meningeal artery and the stylomastoid branch of the posterior auricular artery form the facial arcade as the major supply to the facial nerve, and the neuromeningeal trunk of the ascending pharyngeal artery supplies the lower cranial nerves (CN IX–XII).

BACKGROUND AND PURPOSE: Localization of the culprit CSF leak in patients with spontaneous intracranial hypotension can be difficult and is inconsistently achieved. We present a high yield systematic imaging strategy using brain and spine MRI combined with digital subtraction myelography for CSF leak localization. MATERIALS AND METHODS: During a 2-year period, patients with spontaneous intracranial hypotension at our institution underwent MR imaging to determine the presence or absence of a spinal longitudinal extradural collection. Digital subtraction myelography was then performed in patients positive for spinal longitudinal extradural CSF collection primarily in the prone position and in patients negative for spinal longitudinal extradural CSF collection in the lateral decubitus positions. RESULTS: Thirty-one consecutive patients with spontaneous intracranial hypotension were included. The site of CSF leakage was definitively located in 27 (87%). Of these, 21 were positive for spinal longitudinal extradural CSF collection and categorized as having a ventral (type 1, fifteen [48%]) or lateral dural tear (type 2; four [13%]). Ten patients were negative for spinal longitudinal extradural CSF collection and were categorized as having a CSF-venous fistula (type 3, seven [23%]) or distal nerve root sleeve leak (type 4, one [3%]). The locations of leakage of 2 patients positive for spinal longitudinal extradural CSF collection remain undefined due to resolution of spontaneous intracranial hypotension before repeat digital subtraction myelography. In 2 (7%) patients negative for spinal longitudinal extradural CSF collection, the site of leakage could not be localized. Nine of 21 (43%) patients positive for spinal longitudinal extradural CSF collection were treated successfully with an epidural blood patch, and 12 required an operation. Of the 10 patients negative for spinal longitudinal extradural CSF collection (8 localized), none were effectively treated with an epidural blood patch, and all have undergone (n = 7) or are awaiting (n = 1) an operation. CONCLUSIONS: Patients positive for spinal longitudinal extradural CSF collection are best positioned prone for digital subtraction myelography and may warrant additional attempts at a directed epidural blood patch. Patients negative for spinal longitudinal extradural CSF collection are best evaluated in the decubitus positions to reveal a CSF-venous fistula, common in this population. Patients with CSF-venous fistula may forgo further epidural blood patch treatment and go on to surgical repair.

OJECTIVES Presurgical mapping of motor function is a widely used clinical application of functional (f) MRI, employing the blood oxygenation level dependent contrast. The aim of this study was to report on 3 years experience of 194 fMRI studies on the representation of motor function in 103 patients and to describe the problems and artefacts that were typically present. METHODS An evaluation was carried out to determine whether the patients' age, type or location of the tumourous lesion, severity of the paresis, or the tasks used during the investigation have an effect on artefacts of fMRI studies and how these artefacts are best overcome. RESULTS Functional MRI identified the motor regions in 85% of all investigated paradigms. In 11% of the investigated patients no information at all on functional localisation was obtained. A draining vein within the central sulcus was present in all patients that showed activation within the parenchyma of the precentral gyrus but also in three patients in whom no parenchymal activation was present. Head movement artefacts were the most frequent cause for fMRI failure, followed by low signal to noise ratio. Motion artefacts were correlated with the degree of paresis and with the functional task. Tasks involving more proximal muscles led to significantly more motion artefacts when compared with tasks that primarily involved distal muscles. Mean MR signal change during task performance was 2.5%. CONCLUSIONS Most of the artefacts of functional MRI can be reliably detected and at least in part be reduced or eliminated with the help of mathematical algorithms, appropriate pulse sequences and tasks, and—probably most important—by evaluating the fMRI raw data—that is, the MR signal time courses.