Journal Scan – This Month in Other Journals, October 2017

Horn A, Reich M, Vorwerk J, et al. Connectivity Predicts deep brain stimulation outcome in Parkinson disease. Ann Neurol. 2017;82(1):67-78. doi:10.1002/ana.24974.

The benefit of deep brain stimulation (DBS) for Parkinson disease (PD) may depend on connectivity between the stimulation site and other brain regions, but which regions and whether connectivity can predict outcome in patients remain unknown. The authors attempted to identify the structural and functional connectivity profile of effective DBS to the subthalamic nucleus (STN) and test its ability to predict outcome.

The authors utilized a training dataset of 51 PD patients with subthalamic nucleus DBS which was combined with publicly available human connectome data (diffusion tractography and resting state functional connectivity) to identify connections reliably associated with clinical improvement (motor score of the Unified Parkinson Disease Rating Scale [UPDRS]). This connectivity profile was then used to predict outcome in an independent cohort of 44 patients. Resting state functional connectivity data was obtained on 1,000 healthy subjects using a 3T Siemens (Erlangen, Germany) MRI, part of the Brain Genomics Superstruct Project (https://dataverse.harvard.edu/dataverse/GSP). MRI data from 90 patients were obtained from the Parkinson’s Progression Markers Initiative (PPMI) database.  Scanning parameters can be found on the project website (www.ppmi-info.orgz). In the training dataset, connectivity between the DBS electrode and a distributed network of brain regions correlated with clinical response including structural connectivity to supplementary motor area and functional anticorrelation to primary motor cortex. This same connectivity profile predicted response in an independent patient cohort.

The authors cite four main conclusions: 1) a specific pattern of structural and functional connectivity with subthalamic nucleus DBS electrodes correlates with clinical outcome across patients in PD. 2) structural and functional connectivity are independent predictors of DBS response. 3) connectivity profiles derived from one patient cohort can predict clinical outcome in an independent cohort from a different DBS center. 4) They illustrate the potential of how connectivity profiles may be used to estimate outcome in single patients.

6 Figures

Sandwell S, Walter K, Westesson P-L. Pseudomeningocele Aspiration and Blood Patch Effectively Treats Positional Headache Associated With Postoperative Lumbosacral Pseudomeningocele. Spine (Phila Pa 1976). 2017;42(15):1139-1144. doi:10.1097/BRS.0000000000002003.

Pseudomeningocele is one of the most common complications after posterior lumbosacral spinal surgery. Common treatments include bedrest, abdominal binder use, subarachnoid lumbar drainage, and surgical reexploration for durotomy closure. Only small case reports support the use of epidural blood patch injection for symptomatic pseudomeningocele treatment. This retrospective chart review analyzed the outcomes and complications of 19 consecutive patients who underwent blood patch injection, with and without pseudomeningocele aspiration, for symptomatic postoperative lumbosacral pseudomeningoceles between 2009 and 2015. As of last follow-up (average time 22.3 months), 16 patients (84%) experienced headache resolution after blood patch injection and did not require further treatment of their pseudomeningocele. In addition to symptomatic improvement, 12 of the 16 successful patients had imaging, which demonstrated pseudomeningocele resolution.

Technique:
An 18-gauge 3.5-inch needle is passed into the pseudomeningocele under fluoroscopic guidance to approach the subfascial midline posterior to the appropriate spinal level. If possible, the pseudomeningocele is aspirated completely and the volume recorded. Under fluoroscopic monitoring, 2 cc of iohexal 300 contrast is injected into the pseudomeningocele. Next, a volume of autologous venous blood, near equal to that aspirated, is injected into the pseudomeningocele cavity through the same needle. The blood is not combined with contrast prior to patch injection. The blood should be used immediately after it has been drawn from the intravenous access. Multiple 10-cc syringes can be used to allow blood to be drawn as needed and then injected within 30 seconds of blood draw.  A 22-gauge Touhey needle is then placed in the epidural space just above the level of the pseudomeningocele. Position is confirmed fluoroscopically with contrast. Additional venous blood is injected in the epidural space above the pseudomeningocele. The amount of blood injected is determined by the patients’ symptoms during the injection. The total volumes of each patient’s pseudomeningocele and epidural injection ranged from 7 to 50mL.

1 Figure, 1 Table

Bette S, Gempt J, Huber T, et al. FLAIR signal increase of the fluid within the resection cavity after glioma surgery: generally valid as early recurrence marker? J Neurosurg. 2017;127(2):417-425. doi:10.3171/2016.8.JNS16752.

Recent studies have shown that signal increase of the fluid within the resection cavity on T2-weighted FLAIR sequences predicts early tumor recurrence in partially resected glioma with a high specificity. The aim of this study was to assess the increase in FLAIR signal intensity in a large patient cohort and in subgroups to assess its prognostic value for early tumor recurrence.

A total of 212 patients (213 cases) who had undergone surgery for glioma (WHO Grade IV [n = 103], WHO Grade III [n = 57], and WHO Grade II [n = 53]) were included in this retrospective study. FLAIR signal within the resection cavity at the time of tumor recurrence/last contact and on the previous MRI study was assessed qualitatively and quantitatively. Appearance of FLAIR signal increase was studied over time using Kaplan-Meier estimates in subgroups.

After excluding low grade gliomas where the resection cavity was in communication with the CSF spaces they were left with data for 87 cases. FLAIR signal intensity increase was observed in 27 of these cases. Recurrent disease was found in 26 of these 27 cases, resulting in a specificity of 80.0%, a sensitivity of 31.7%, and positive and negative predictive values of 96.3% and 6.7%, respectively. In 4 cases this sign had been observed prior (range 2.8–8.5 months) to tumor recurrence defined by standard criteria.

They conclude that an increase in FLAIR signal intensity of the fluid within the resection cavity of gliomas is a highly specific and early sign for tumor recurrence/tumor progression and can easily be used in the clinical routine. As this sign is mainly observed in patients with high-grade gliomas (WHO III and IV) who have undergone radiotherapy, and without connection of the resection cavity to CSF, and its use should be limited to this subgroup.

6 Figures, 3 Tables

Zuckerman SL, Kreines F, Powers A, et al. Stabilization of Tumor-Associated Craniovertebral Junction Instability: Indications, Operative Variables, and Outcomes. Neurosurgery. 2017;81(2):251-258. doi:10.1093/neuros/nyx070.

This single-institutional case series reviews the management of patients with primary or metastatic tumors of the CVJ undergoing occipitocervical (OC) stabilization using a cervical screw-rod system affixed to a midline keel suboccipital buttress plate. The objective of this study was to describe the surgical indications, operative variables, and outcomes in this population.

Ten patients (26%) harbored primary tumors, and the remaining 29 (74%) had metastatic disease. Of the metastatic patients, 14 had a neurological deficit, 10 had severe neck pain, and 5 were deemed mechanically unstable. Postoperative visual analog pain scores were significantly reduced at all 3 follow-up times. The percentage of patients who were ambulatory and neurologically improved or intact remained stable postoperatively with no significant declines. There were 2 perioperative mortalities (5%), and 13 patients (33%) experienced a major complication.

One patient expired as a result of postoperative pneumonia and a second patient expired 5 days after discharge while in hospice care as a result of disease progression. Thirteen patients (33%) experienced a major perioperative complication, including wound infection, pneumonia, aspiration requiring tracheostomy, pulmonary embolism, deep vein thrombosis, vertebral artery occlusion, and ischemic cardiomyopathy.

They conclude that in patients with primary or metastatic tumor of the CVJ, OC stabilization using a cervical screw-rod system affixed to a midline-keel buttress plate, with or without posterior decompression, is a reliable method for CVJ stabilization in the oncologic setting. Improvement in pain and preservation of neurological function was seen.

2 Figures, 4 Tables

Della Pepa GM, Parente P, D’Argento F, et al. Angio-Architectural Features of High-Grade Intracranial Dural Arteriovenous Fistulas: Correlation With Aggressive Clinical Presentation and Hemorrhagic Risk. Neurosurgery. 2017;81(2):315-330. doi:10.1093/neuros/nyw175.

Intracranial dural arteriovenous fistulas (dAVF) are acquired lesions consisting of a direct arteriovenous shunt, located in the dural layer, near a dural sinus. The blood supply comes from branches or dural meningeal branches of the cerebral arteries, while their drainage is carried out through the brain venous system.

Classically, the clinical manifestations are classified into 3 major categories: (I) benign clinical presentation, (II) aggressive clinical presentation, and (III) hemorrhagic event.

Symptoms of benign presentation include:
Tinnitus
Headache
Dizziness
Conjunctival chemosis
Exophthalmos
Decreased visual acuity (not associated with glaucoma)

Aggressive presentation includes:
Progressive neurological deficit
Transitory ischemic attack
Epilepsy
Intracranial hypertension syndrome
Cranial nerve deficits
Facial nerve paralysis
Glaucoma with irreversible decrease in visual acuity

dAVFs’ annual risk of bleeding has been estimated between 1.5% and 1.8% per year. However, the risk of hemorrhage varies according to vascular characteristics of the dAVF. It depends on 2 factors: (a) the model of the venous drainage and in particular the presence of venous cortical reflux and (b) the presence or absence of aggressive symptoms at clinical presentation.

Forty-nine patients were included in the final series. Thirty-five cases presented cortical venous reflux (Borden grades 2 and 3 or Cognard 2b, 2a + b, 3, and 4). Within this subgroup, the pattern of venous drainage was analyzed in relation to clinical presentation, and in particular has evaluated the possible correlation between indicators of venous hypertension and clinical course. This subgroup displayed a benign presentation in 31.42% of cases, an aggressive in 31.42%, and hemorrhage in 37.14%.

The authors conclude that the data confirms that within high-grade dAVFs, 2 distinct subpopulations exist according to severity of clinical presentation. Some indicators that they examined showed correlation with aggressive nonhemorrhagic manifestations (outflow restriction and pseudophlebitic cortical vessels), while other showed a correlation with hemorrhage (dual thrombosis and venous aneurysms). The current classifications appear insufficient to identify a wide range of conditions that ultimately determine the organization of the cortical venous drainage. Intermediate degrees of venous congestion correlate better with the clinical risk than the simple definition of cortical reflux.

12 Figures, 6 Tables

Abdulrauf SI, Vuong P, Patel R, et al. “Awake” clipping of cerebral aneurysms: report of initial series. J Neurosurg. 2017;127(2):311-318. doi:10.3171/2015.12.JNS152140.

Risk of ischemia during aneurysm surgery is significantly related to temporary clipping time and final clipping that might incorporate a perforator. In this study, the authors attempted to assess the potential added benefit to patient outcomes of “awake” neurological testing when compared with standard neurophysiological testing performed under general anesthesia. The authors conducted a prospective study of clipping unruptured intracranial aneurysms (UIAs) in 30 consecutive adult patients who underwent awake clipping. The end points were the incidence of stroke/cerebrovascular accident (CVA), death, discharge to a long-term facility, length of stay, and 30-day modified Rankin Scale score. Twenty-seven (90%) aneurysms were anterior, and 3 (10%) were posterior circulation aneurysms. Five (17%) had been coiled previously, 3 (10%) had been clipped previously, 2 (7%) were partially calcified, and 2 (7%) were fusiform aneurysms. Three patients developed synchronous clinical neurological and neurophysiological changes during temporary clipping with consequent removal of the temporary clip and reversal of those clinical and neurophysiological changes. Three patients developed asynchronous clinical neurological and neurophysiological changes. These 3 patients developed hemiparesis without changes in neurophysiological monitoring results. One patient developed linked clinical neurological and neurophysiological changes during final clipping that were not reversed by reapplication of the clip, and the patient had a CVA. Four patients with internal carotid artery ophthalmic segment aneurysms underwent visual testing with final clipping, and 1 of these patients required repositioning of the clip. The authors conclude that the 3 patients who developed neurological deterioration without a concomitant neurophysiological finding during temporary clipping revealed a potential advantage of awake aneurysm surgery (i.e., in decreasing the risk of ischemic injury).

5 Figures, 1 Table

Gong D, Yu H, Yuan X. A new method of subarachnoid puncture for clinical diagnosis and treatment: lateral atlanto-occipital space puncture. J Neurosurg. July 2017:1-7. doi:10.3171/2017.1.JNS161089.

Lumbar puncture may not be suitable for some patients needing subarachnoid puncture, while lateral C1–2 puncture and cisterna magna puncture have safety concerns. This study investigated lateral atlanto-occipital space puncture (also called lateral cisterna magna puncture) in patients who needed subarachnoid puncture for clinical diagnosis or treatment. From March 1995 to March 2015, 667 patients hospitalized in the Department of Neurology, Liaocheng People’s Hospital, received 1008 lateral atlanto-occipital space puncture procedures for clinical diagnosis or treatment. Of the 667 patients, 389 (58.32%) were male and 278 (41.68%) were female. Their ages ranged from 5 to 88 years. Two hundred twenty-nine of the patients had refractory neurological diseases and were undergoing treatment with human umbilical cord blood mononuclear cell transplantation; these patients were treated between July 2011 and March 2015.

The indications for lateral atlanto-occipital space puncture were as follows: 1) inflammation of the CNS; 2) diagnosis of subarachnoid hemorrhage in patients with negative brain CT or difficult differential diagnosis of meningitis; 3) CSF replacement or intrathecal drug therapy; 4) stem cell transplantation; 5) diagnosis and differential diagnosis of demyelinating disease; 6) treatment of ventricular hemorrhage; 7) alternative to difficult LP; 8) rescue of patients with brain herniation of varying causes; or 9) need for CSF specimen or intrathecal treatment in critically ill patients who were not suitable candidates for LP or radiographic investigation.

Of 1008 lateral atlanto-occipital space punctures, 991 succeeded and 17 failed (1.7%). Fifteen patients (2.25%) reported pain in the ipsilateral external auditory canal or deep soft tissue, 32 patients (4.80%) had a transient increase in blood pressure, and 1 patient (0.15%) had intracranial hypotension after the puncture. They conclude that this approach is associated with a lower rate of complications than lateral C1–2 puncture or traditional (suboccipital) cisterna magna puncture. It may have potential in the neurological diagnostic and treatment fields.

“No important blood vessels or nerves run very close to the puncture route”….wait a minute, what?  Pretty sure I will never do this approach.

5 Figures

Hu J, Ni S, Cao Y, Wang X, Liao S, Lu H. Comparison of Synchrotron Radiation-based Propagation Phase Contrast Imaging and Conventional Micro-computed Tomography for Assessing Intervertebral Discs and Endplates in a Murine Model. Spine (Phila Pa 1976). 2017;42(15):E883-E889. doi:10.1097/BRS.0000000000002110.

Stick with me on this one….basic science proof of concept study where the technique is the interesting aspect.

Synchrotron radiation (SR) x-ray source has been widely used in medical research. It has favorable characteristics of monochromatization coupled with high photon flux and coherence that make it appropriate for high resolution imaging of biological tissue. Based on SR light source, x-ray propagation phase contrast imaging (PPCI) is approximately 1000 times more sensitive to refractive index information than traditional x-ray imaging. Propagation phase contrast imaging is an ideal way to distinguish internal microstructure, especially in tissues that have small differences in absorption coefficients. Propagation phase contrast imaging combined with an SR source is a promising method to visualize and reconstruct the 3D microstructure of biological tissue, including soft and fibrous tissue, with ultrahigh resolution.

The principle of propagation phase contrast imaging is based on the Fresnel diffraction theory, which provides an edge-enhancement effect of the sample. The image formed not only comes from the absorption of x-rays but also the phase shift induced by the object. Both the absorption and phase contrast intensity can be captured by the detector as long as the interaction between the wave and the object is strong enough.

The aim of this study was (i) to compare the differences between SRmCT and mCT in the detection of 3D structures in IVD and EP and (ii) to investigate the morphological and structural changes of IVD and EP in mice during maturation and aging from a 3D perspective. The 3D reconstructed model of the EP from both mCT and SRmCT provided detailed information on its inner structure. However, the IVD was only depicted using SRmCT. Multi-angle observations of the 3D structure of EP and IVD from mice of different ages were dynamically performed by SRmCT. Quantitative evaluations indicated that the total volume of EP and IVD, the average height of IVD and the canal-total volume ratio of EP increased from 15-day-old mice to 4-month-old mice and decreased in 18-month-old mice.

 

Journal Scan – This Month in Other Journals, October 2017
jross
Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.