Unilateral Pedicle Screw Fixation is Associated with Reduced Cost and Similar Outcomes in Selected Patients Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion for L4-5 Degenerative Spondylolisthesis.

STUDY DESIGN: Retrospective study of 24 patients who underwent either a bilateral or unilateral TLIF procedure for the treatment of degenerative spondylolisthesis. OBJECTIVE: To analyze differences in cost and outcome between patients undergoing minimally invasive transforaminal lumbar interbody fusion (mi-TLIF) with unilateral or bilateral pedicle screw fixation for L4-5 degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Lumbar fusion surgeries, including the TLIF procedure, have been shown to be an effective treatment for leg and low back pain caused by degenerative spondylolisthesis. Some studies have shown TLIF surgeries to be cost-effective, but there is still a paucity of data and no consensus. Unilateral TLIFs can provide the same benefits as bilateral TLIFs, but come with additional benefits of a less invasive surgery. METHODS: We retrospectively analyzed a consecutive series of patients with L4-5 degenerative stenosis and spondylolisthesis who either received a unilateral or bilateral mi-TLIF, paying particular attention to hospital cost and clinical outcome. Of the 33 patients eligible for analysis, we were able to obtain appropriate clinical and radiographic follow-up data on 24 patients (72.7%), 14 patients who underwent unilateral fixation, and 10 patients who underwent bilateral fixation. RESULTS: The cohorts were similar with regard to age, comorbidities, and demographics. Most patients reported good or excellent results, and there were no significant differences between the cohorts with regard to clinical outcome. There was one interbody graft extrusion in the unilateral cohort that required explantation, but no other hardware failures. Hospital cost was significantly lower in the unilateral cohort, and hardware savings accounted for only part of the difference. CONCLUSION: Unilateral pedicle screw fixation is an acceptable surgical strategy in patients with stable L4-5 degenerative spondylolisthesis undergoing mi-TLIF. In our series, unilateral fixation led to significant hospital cost savings without compromising clinical or radiographic outcomes.

Y-Stent embolization technique for intracranial bifurcation aneurysms.

Wide-necked bifurcation aneurysms often require the use of the technically complex Y-stent technique, which has recently been shown to narrow bifurcation angle in a hemodynamically favorable manner. We sought to evaluate the single center efficacy and safety of Y-stent supported aneurysm coil embolization. All patients undergoing Y-stent supported coiling between September 2006 and December 2012 were identified; records were analyzed for procedural results and complications, with follow-up evaluated for occlusion rate and neurological adverse events. Twenty consecutive patients underwent technically successful Y-stent supported coiling, with complete aneurysm occlusion achieved in 19/20 cases (95%). There were no peri-procedural clinically evident neurological complications following Y-stenting. Clinical follow-up was available for a mean of 20.0months and radiographic follow-up was available for a mean of 18.5months. During the follow-up period, three patients (15%) required re-treatment with through-stent coiling for recanalization. At latest follow-up, Raymond grade I occlusion was achieved in 16 patients (80%), Raymond grade II occlusion achieved in four patients (20%) and Raymond grade III occlusion in zero patients. Y-stenting for complex intracranial aneurysms appears effective in achieving durable aneurysm occlusion with an acceptable safety profile. Though the procedure is technically more complex than single-stent procedures, the Y-stent configuration should be considered when single-stent supported coiling is not feasible or sufficient.

Stent recanalization of carotid tonsillar loop dissection using the Enterprise vascular reconstruction device.

Although advances in endovascular techniques have permitted reconstruction of intimal dissections and related pseudoaneurysms of the extracranial cervical internal carotid artery, highly tortuous tonsillar loop anatomic variants still pose an obstacle to conventional extracranial self-expanding carotid stents. During a 12 year period, nine of 48 cases with cervical carotid dissections were associated with a tonsillar loop. Five patients required endovascular treatment, which was performed using a microcatheter-based technique with the low-profile Enterprise vascular reconstruction device (Codman Neurovascular, Raynham, MA, USA). Technical, radiographic, and clinical outcomes were analyzed for each patient. Dissection etiology was spontaneous in three patients, iatrogenic in one, and traumatic in one. Four near-occlusive tonsillar loop dissections were successfully recanalized during the acute phase. Dissection-related stenosis improved from 90±22% to 31±13%, with tandem stents needed in three instances to seal the inflow zone. There were no procedure-related transient ischemic attacks (TIA), minor/major strokes, or deaths. Angiographic follow-up for a mean of 28.0±21.6 months showed all stents were patent, with average stenosis of 25.2±12.2%. Focal ovalization and kinking of the closed-cell design was noted at the sharpest curve in one patient. Clinical outcome (follow-up of 28.1±21.5 months) demonstrated overall improvement with no clinical worsening, new TIA, or stroke. Tonsillar loop-associated carotid dissections can be successfully and durably recanalized using the low-profile Enterprise stent with an excellent long-term patency rate and low procedural risk. The possibility of stent kinking and low radial force should be considered when planning reconstruction with this device.

Benefit of a sharp computed tomography angiography reconstruction kernel for improved characterization of intracranial aneurysms.

BACKGROUND: Computed tomography angiography (CTA) is the first-line imaging modality used for cerebral aneurysms because of its speed and sensitivity for detection, although digital subtraction angiography is often required for more detailed aneurysm shape delineation. OBJECTIVE: To determine whether a sharper CTA reconstruction kernel can better characterize an aneurysm and improve decision-making before intervention. METHODS: Fifteen patients presenting with aneurysmal subarachnoid hemorrhage underwent 64-row CTA. CTA data were reconstructed using the default H20f smooth kernel and a H60f sharp kernel and compared with contemporaneous catheter 3-dimensional rotational angiography (3DRA). Aneurysm neck, width, and aspect ratio measurements were made using intensity line plots of identical projections on all imaging datasets and compared by matched-pair statistics. RESULTS: Aneurysm neck measurements from the H20f smooth kernel revealed overestimation compared with both the sharp kernel (greater by 0.64 ± 0.21 mm, P < .01) and 3DRA (greater by 0.68 ± 0.19 mm, P < .01). There was no statistically significant difference between 3DRA and the sharp kernel CTA measurements. Neck measurements correlated well between the H60f kernel and 3DRA but not between the H20f Kernel and 3DRA (R 0.97 vs 0.86). CONCLUSION: H60f sharp CTA kernel reconstruction provides more accurate anatomic characterization of cerebral aneurysms than the H20f smooth kernel at the expense of less visually pleasing reconstructions. Because it does not require additional contrast, radiation, or imaging hardware and is more similar to 3DRA, it may aid in selecting the appropriate treatment strategy before to evaluation by catheter-based angiography.

Use of concentric Solitaire stent to anchor Pipeline flow diverter constructs in treatment of shallow cervical carotid dissecting pseudoaneurysms.

The flow-diverting Pipeline Embolization Device (PED; ev3 Neurovascular, Irvine, CA, USA) provides proven flow diversion for intracranial wide-necked and fusiform aneurysms. The tendency of the PED to migrate and foreshorten when its size is mismatched with the parent vessel makes its use more difficult for cervical carotid pseudoaneurysms, as the parent vessel regains its luminal diameter during the healing phase, and because of its mobility during head movement. We present a novel technique of using a Solitaire detachable stent (ev3 Neurovascular) to anchor PED constructs to mitigate these shortcomings. Two patients with shallow and broad-necked cervical carotid pseudoaneurysms with underlying parent vessel stenosis deemed poor candidates for conventional stent-supported coiling were treated using tandem overlapping PED centered over the neck of the pseudoaneurysm and a Solitaire concentric anchor was deployed to overlap distally and proximally. As predicted, both patients revealed carotid luminal gain after aneurysm thrombosis with attendant migration (3.8 and 2.8mm) and expansion of the PED construct (14% and 7.8%) which remained constrained within the Solitaire anchoring device with persistent luminal patency and no evidence of endoleak at follow-up (3 and 5 months). The use of a concentric anchoring stent can mitigate the inherent tendency of the braided flow-diverting PED to migrate and foreshorten as the target vessel heals upon pseudoaneurysm thrombosis. This novel technique opens the possibility of using PED to treat shallow or fusiform lesions in mobile cervical arteries previously relegated to stent-supported coiling or surgical reconstruction.

Double waffle-cone technique using twin Solitaire detachable stents for treatment of an ultra-wide necked aneurysm.

Several stent-supported coiling techniques have been devised for treating wide-necked bifurcation aneurysms including the Y-stent and waffle-cone constructs. The Y-stent technique is not technically possible with obtusely oriented daughter vessels, and the waffle-cone method is inadequate for aneurysms with necks exceeding the stent's maximal expansion diameter. We describe here the novel use of the Solitaire electrolytically detachable slotted stent (Solitaire, ev3, Irvine, CA, USA) featuring large-sized cells to fashion a concentric "double waffle-cone" construct. This method enabled the doubling of the neck coverage to treat an ultra-wide necked middle cerebral aneurysm with obtusely oriented daughter branches. The technique relies on the intra-cell crossing of the first stent using the second stent delivery microcatheter and fine tuning the relative position with the aid of cross-sectional cone-beam computed tomographic angiography to achieve optimal coverage of the neck prior to detachment of the stents in position. A retrievable stent with large cells such as the Solitaire device is optimal for this application given the need for relative adjustment of the deployment before final stent release to avoid under- or over-penetration of the distal stent struts into the aneurysm dome. An additional advantage of this approach over the kissing-stent technique is the absence of intraluminal stent struts, which was confirmed here by down-the-barrel cross-sectional imaging. The double waffle-cone construct enabled the successful coiling of the aneurysm with no post-procedural ischemic events detected on diffusion-weighted MRI and with stable complete embolization and no residual filling or in-stent stenosis at 6 month follow-up.

Superior performance of cone-beam CT angiography in characterization of intracranial atherosclerosis.

OBJECT: Intracranial atherosclerotic disease (ICAD) carries a high risk of stroke. Evaluation of ICAD has focused on assessing the absolute degree of stenosis, although plaque morphology has recently demonstrated increasing relevance. The authors provide the first report of the use of ultra-high-resolution C-arm cone-beam CT angiography (CBCT-A) in the evaluation of vessel stenosis as well as plaque morphology. METHODS: Between August 2009 and July 2012, CBCT-A was used in all patients with ICAD who underwent catheter-based angiography at the authors' institution (n = 18). Lesions were evaluated for maximum degree of stenosis as well as plaque morphological characteristics (ulcerated, calcified, dissected, or spiculated) via digital subtraction angiography (DSA), 3D-rotational angiography (3DRA), and CBCT-A. The different imaging modalities were compared in their assessment of absolute stenosis as well as their ability to resolve different plaque morphologies. RESULTS: Lesions were found to have similar degrees of stenosis when utilizing CBCT-A compared with 3DRA, but both 3DRA and CBCT-A differed from DSA in their assessment of the absolute degree of stenosis. CBCT-A provided the most detailed resolution of plaque morphology, identifying a new plaque characteristic in 61% of patients (n = 11) when compared with DSA and 50% (n = 9) when compared with 3DRA. CBCT-A identified all lesion characteristics visualized on DSA and 3DRA. CONCLUSIONS: CBCT-A provides detailed spatial resolution of plaque morphology and may add to DSA and 3DRA in the evaluation of ICAD. Further prospective study is warranted to determine any benefit CBCTA-A may provide in clinical decision making and risk stratification over existing conventional imaging modalities.

Use of cone-beam computed tomography angiography in planning for gamma knife radiosurgery for arteriovenous malformations: a case series and early report.

BACKGROUND: The effectiveness of Gamma Knife radiosurgery (GKR) for cerebral arteriovenous malformations (AVMs) is predicated on inclusion of the entire nidus while excluding normal tissue. As such, GKR may be limited by the resolution and accuracy of the imaging modality used in targeting. OBJECTIVE: We present the first case series to demonstrate the feasibility of using ultrahigh-resolution C-arm cone-beam computed tomography angiography (CBCT-A) in AVM targeting. METHODS: From June 2009 to June 2013, CBCT-A was used for targeting of all patients with AVMs treated with GKR at our institution. Patients underwent Leksell stereotactic head frame placement followed by catheter-based biplane 2-dimensional digital subtraction angiography, 3-dimensional rotational angiography, as well as CBCT-A. The CBCT-A dataset was used for stereotactic planning for GKR. Patients were followed at 1, 3, 6, and 12 months and then annually thereafter. RESULTS: CBCT-A-based targeting was used in 22 consecutive patients. CBCT-A provided detailed spatial resolution and sensitivity of nidal angioarchitecture enabling treatment. The average radiation dose to the margin of the AVM nidus corresponding to the 50% isodose line was 15.6 Gy. No patient had treatment-associated hemorrhage. At early follow-up (mean, 16 months), 84% of patients had a decreasing or obliterated AVM nidus. CONCLUSION: CBCT-A-guided radiosurgery is feasible and useful because it provides sufficient detailed resolution and sensitivity for imaging brain AVMs.

Benefit of cone-beam computed tomography angiography in acute management of angiographically undetectable ruptured arteriovenous malformations.

OBJECT: Ruptured arteriovenous malformations (AVMs) are a frequent cause of intracerebral hemorrhage (ICH). In some cases, compression from the associated hematoma in the acute setting can partially or completely occlude an AVM, making it invisible on conventional angiography techniques. The authors report on the successful use of cone-beam CT angiography (CBCT-A) to precisely identify the underlying angioarchitecture of ruptured AVMs that are not visible on conventional angiography. METHODS: Three patients presented with ICH for which they underwent examination with CBCT-A in addition to digital subtraction angiography and other imaging modalities, including MR angiography and CT angiography. All patients underwent surgical evacuation due to mass effect from the hematoma. Clinical history, imaging studies, and surgical records were reviewed. Hematoma volumes were calculated. RESULTS: In all 3 cases, CBCT-A demonstrated detailed anatomy of an AVM where no lesion or just a suggestion of a draining vein had been seen with other imaging modalities. Magnetic resonance imaging demonstrated enhancement in 1 patient; CT angiography demonstrated a draining vein in 1 patient; 2D digital subtraction angiography and 3D rotational angiography demonstrated a suggestion of a draining vein in 2 cases and no finding in the third. In the 2 patients in whom CBCT-A was performed prior to surgery, the demonstrated AVM was successfully resected without evidence of a residual lesion. In the third patient, CBCT-A allowed precise targeting of the AVM nidus using Gamma Knife radiosurgery. CONCLUSIONS: Cone-beam CT angiography should be considered in the evaluation and subsequent treatment of ICH due to ruptured AVMs. In cases in which the associated hematoma compresses the AVM nidus, CBCT-A can have higher sensitivity and anatomical accuracy than traditional angiographic modalities, including digital subtraction angiography.

Temporal craniotomy for surgical access to the infratemporal fossa.

We propose a surgical approach for select patients that minimizes morbidity while allowing gross total resection of lesions in the anterior portion of the infratemporal fossa. The approach we describe is an extradural approach through a subtemporal craniectomy or craniotomy with the possible addition of a zygomatic osteotomy. Lesions that have a well-defined capsule and a texture that permits manipulation are ideal for this less invasive approach. We retrospectively reviewed six cases from the primary author (C.B.H.) using a temporal craniectomy or craniotomy alone to resect lesions in the infratemporal fossa. All six cases had good clinical outcomes with no unexpected neurological deficits while achieving gross total resections. The only complication included one cerebrospinal fluid leak that was sealed endoscopically. For select lesions, a less morbid surgical approach via an extradural window through a subtemporal craniectomy or small craniotomy may be preferable to transfacial approaches. Adjuvant use of endoscopic techniques may facilitate surgical exposure and resection of large lesions.