Danial K. Hallam

Intraventricular tissue plasminogen activator for the prevention of vasospasm and hydrocephalus after aneurysmal subarachnoid hemorrhage

BACKGROUNDThe sequelae of aneurysmal subarachnoid hemorrhage (SAH) include vasospasm and hydrocephalus. OBJECTIVETo assess whether intraventricular tissue plasminogen activator (tPA) results in less vasospasm, fewer angioplasties, or fewer cerebrospinal fluid shunting procedures. METHODS41 patients (tPA group, Hunt and Hess 3, 4, 5) from 2007 to 2008 received intraventricular tPA and lumbar drainage for a minimum of 5 days (range 5–7 days) and were compared to a matched group of 35 patients from 2006 to 2007 (Control, HH 3, 4, 5). Statistical comparison was done by t test analysis or Fisher exact tests and data are expressed as average ± standard error of the mean. RESULTSThere were no significant differences in demographic data, although the tPA group had a trend toward more surgical patients. The tPA group of patients had a significantly higher modified Fisher grade than controls (P < .001) and had a significantly better Hunt and Hess grade than controls (P < .03). The angioplasty rate was significantly lower among the tPA patients (15.0% ± 5.6) than controls (40.0% ± 8.5, P = .019). The number of days spent in severe vasospasm normalized over the 14-day monitoring period by transcranial Doppler was significantly lower in the tPA group (0.09 ± 0.02) than controls (0.17 ± 0.03). The shunt rate was significantly lower among tPA patients (17.5% ± 6.0) than controls (42.8% ± 8.6). There were 2 clinically silent tract hemorrhages in the tPA group (4.8%). CONCLUSIONIntraventricular tPA is a safe and effective treatment for reducing both angioplasty and shunting rates in patients with SAH H&H Grades 3 to 5. A randomized trial is indicated.

Evidence-based approach to use of MR imaging in acute spinal trauma

MR imaging directly shows integrity of spinal cord, and provides sensitive assessments of structurally important soft tissue investments of the vertebral column. High-resolution images should be acquired in at least two planes, with T1 and fluid sensitive sequences. In the acute and subacute settings, MR may be used to assess integrity of intervertebral discs prior to closed reduction of inter-facetal dislocations, to discriminate between neurological deficits due to intra-substance hemorrhage or edema, and to determine the status of spinal ligaments as an adjunct to clearing the spine.

Accuracy of Computational Cerebral Aneurysm Hemodynamics Using Patient-Specific Endovascular Measurements

Computational hemodynamic simulations of cerebral aneurysms have traditionally relied on stereotypical boundary conditions (such as blood flow velocity and blood pressure) derived from published values as patient-specific measurements are unavailable or difficult to collect. However, controversy persists over the necessity of incorporating such patient-specific conditions into computational analyses. We perform simulations using both endovascularly-derived patient-specific and typical literature-derived inflow and outflow boundary conditions. Detailed three-dimensional anatomical models of the cerebral vasculature are developed from rotational angiography data, and blood flow velocity and pressure are measured in situ by a dual-sensor pressure and velocity endovascular guidewire at multiple peri-aneurysmal locations in 10 unruptured cerebral aneurysms. These measurements are used to define inflow and outflow boundary conditions for computational hemodynamic models of the aneurysms. The additional in situ measurements which are not prescribed in the simulation are then used to assess the accuracy of the simulated flow velocity and pressure drop. Simulated velocities using patient-specific boundary conditions show good agreement with the guidewire measurements at measurement locations inside the domain, with no bias in the agreement and a random scatter of ≈25%. Simulated velocities using the simplified, literature-derived values show a systematic bias and over-predicted velocity by ≈30% with a random scatter of ≈40%. Computational hemodynamics using endovascularly measured patient-specific boundary conditions have the potential to improve treatment predictions as they provide more accurate and precise results of the aneurysmal hemodynamics than those based on commonly accepted reference values for boundary conditions.

The “Triple-Overlay” Technique for Percutaneous Diagnosis and Treatment of Lesions of the Head and Neck: Combined Three-Dimensional Guidance with Magnetic Resonance Imaging, Cone-Beam Computed Tomography, and Fluoroscopy

OBJECTIVEnAccurate image guidance is an essential component of percutaneous procedures in the head and neck. The combination of preprocedural magnetic resonance imaging (MRI) with cone-beam computed tomography (CBCT) and real-time fluoroscopy (the triple-overlay technique) could be useful in image-guided targeting of lesions in the head and neck.nnnMETHODSnThree patients underwent percutaneous diagnostic or therapeutic procedures of head and neck lesions (mean, 2.3 ± 2.4 cm). One patient presented for biopsy of a small lesion in the infratemporal fossa only visible on MRI, one presented for preoperative embolization of a nasal tumor, and one presented for sclerotherapy of a parotid hemangioma. Preprocedural MRI for each case was merged with CBCT to create a three-dimensional volume for procedural planning. This was then combined with real-time fluoroscopy to create a triple-overlay for needle trajectory and real-time guidance.nnnRESULTSnThe registration of MRI, CBCT, and fluoroscopy was successful for all three procedures, allowing 3D manipulation of the combined images. Percutaneous procedures were successful in all patients without complications.nnnCONCLUSIONSnThe combination of MRI, CBCT, and real-time fluoroscopy provides detailed anatomical information for 3D image-guided percutaneous procedures of the head and neck, especially for small lesions or lesions with features visible only by MRI.

“Stent View” Flat-Detector CT and Stent-Assisted Treatment Strategies for Complex Intracranial Aneurysms

BACKGROUNDnComplex intracranial aneurysms are often treated with endovascular stent-assisted coiling. Intracranial stents are difficult to visualize with conventional computed tomography (CT) or fluoroscopy. Stent view flat-detector CT can be used to visualize intracranial stents during endovascular treatment.nnnMETHODSnThree patients underwent endovascular treatment of complex intracranial aneurysms. Stent view flat-detector CT was used to study stent placement and morphology in vivo.nnnRESULTSnStent view CT was successful in visualizing stents in all patients. In two patients, stent morphology rendered endovascular coiling technically unfeasible; in one patient, visualization of stent strut herniation into the aneurysm lumen allowed successful coil embolization of the aneurysm.nnnCONCLUSIONSnStent view CT provided detailed imaging of stent placement and morphology in all three cases. The technique influenced treatment decisions and technical outcomes. Stent view CT is a valuable intraprocedural technical tool in stent-assisted endovascular procedures.

Endovascular Palliation of AVM-Associated Intractable Trigeminal Neuralgia via Embolization of the Artery of the Foramen Rotundum

OBJECTIVEnu2002 Trigeminal neuralgia is rarely caused by arteriovenous malformations of the posterior fossa. Embolization of aberrant vessels can provide symptomatic relief; however, embolization is not always technically possible, and its effects can be temporary. Embolization of the nerves blood supply could reduce its excitability and provide pain relief.nnnSETTINGnu2002 The study was set in an academic tertiary care center.nnnSTUDY DESIGNnu2002 The study was designed as a report of a clinical case.nnnSUMMARYnu2002 The authors report the case of a 13-year-old girl with a large, unruptured posterior fossa arteriovenous malformation (AVM) presented with left-sided V2-division trigeminal neuralgia. She had undergone multiple previous embolizations of feeding vessels from the anterior inferior cerebellar artery with temporary relief of her symptoms. Embolization of the middle meningeal artery was attempted, but the vessels tortuosity precluded safe catheterization. Instead, the artery of the foramen rotundum, which had minimal contribution to the AVM nidus, was embolized with Onyx copolymer. The patient had immediate cessation of her neuralgia, with a small area of hypesthesia above her left cheek. Complete pain relief lasted for 8 months, followed by a return of mild dysesthesia episodes not requiring intervention.nnnCONCLUSIONnu2002 This case may represent a new method of palliative treatment for AVM-associated trigeminal neuralgia, or potentially trigeminal neuralgia of other etiologies. Based on this cases success, a prospective study using additional provocative testing with intraarterial lidocaine is proposed.

Embolization of carotid-cavernous fistula via direct percutaneous puncture of the inferior ophthalmic vein

Carotid-cavernous fistulas (CCFs) are anomalous connections between the carotid circulation and the cavernous sinus, and may cause significant morbidity. Endovascular treatment of these lesions can be challenging if typical transvenous routes are inaccessible. We describe a case of a Barrow type D carotid-cavernous fistula in which transvenous embolization was attempted via the inferior petrosal sinus (IPS). No connection was found to the fistula, and the superior ophthalmic vein (SOV) was thrombosed. A novel direct percutaneous puncture of the IOV was performed with ultrasound guidance showing that this is a safe alternative route of CCF access and embolization when the IPS and SOV are inaccessible.

Endovascular Procedures with CTA and MRA Roadmapping

Prior to interventional neuroradiology procedures, many patients undergo noninvasive studies such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA). The ability to use these studies during invasive neuroangiographic procedures reduces additional contrast and radiation exposure, and allows for the integration of extravascular imaging.

Radiographic and clinical outcomes in cavernous carotid fistula with special focus on alternative transvenous access techniques

Carotid cavernous fistulae (CCF) are dangerous entities that may cause progressive cranial neuropathy, headache and blindness. Endovascular therapy for CCF is the treatment of choice and can be accomplished with minimal morbidity, but optimal treatment strategies vary according to CCF anatomy. We aimed to define a tailored endovascular treatment algorithm for CCF with a focus on traditional and aberrant venous anatomy. Retrospective cohort analysis of data for 57 patients (age range, 18-90 years, mean 53 years) with CCF (35 direct, 22 indirect) was performed. Treatment was transarterial (n=31), transvenous (n=18), combined (n=2), or observation (n=6). Non-conventional transvenous access (that is, via the facial vein, pterygoid plexus, or via direct puncture of the inferior ophthalmic or frontal vein) was employed in five patients. Mean follow-up period was 12 months. Radiographic cure rate in treated CCF was 96%. Forty-five patients presented with ophthalmic symptoms (chemosis, proptosis, eye pain); all resolved within 6 weeks of successful treatment. Forty-three patients presented with cranial nerve III, IV and/or VI palsy; complete recovery was seen in 54% and partial recovery in 18%. Five patients presented with blindness and five with declining visual acuity. No patient with blindness regained sight after treatment, but all five patients with declining vision recovered some visual acuity. The complication rate was 10.6% (one transient abducens nerve palsy, two symptomatic cerebral infarctions, and three groin hematomas). The permanent complication rate was 3.5%. Multimodal treatment of CCF, including non-traditional routes of transvenous access, results in excellent outcomes and low morbidity.

Balloon test occlusion with the Doppler velocity guidewire.

Transcranial Doppler ultrasonography is the most commonly used method of cerebrovascular blood flow velocity measurement, but it is subject to certain technical and anatomic limitations. The Doppler velocity guidewire measures blood flow velocity within any vessel during cerebral angiography, overcoming these limitations. We report the first use of this guidewire in the measurement of blood flow velocity during balloon test occlusion, with results similar to simultaneously measured transcranial Doppler ultrasonography. Velocity measurement by Doppler guidewire could be useful in balloon test occlusion for vertebrobasilar circulation, where transcranial Doppler ultrasonography is limited, and provide anatomically specific blood flow velocity measurements in the diagnosis and treatment of stroke and other cerebrovascular diseases.