Please check out the accompanying podcast of this blog post (also known as “Annotated Bibliography”):
1. Kuchcinshi G, Mellerio C, Pallud J, et al. Three-tesla functional MR language mapping: Comparison with direct cortical stimulation in gliomas. Neurology. 2015;84:560–568.
The authors evaluated 3T fMRI language mapping to direct cortical stimulation (DCS) during awake surgery in 40 patients with supratentorial gliomas (24 low-grade, 16 high-grade). They aimed to identify the clinical, histopathologic, and radiologic factors associated with fMRI/DCS discrepancies. Three block-designed tasks were performed during fMRI (letter word generation, category word generation, semantic association). They found that the sensitivity and specificity of fMRI combining the three tasks was 37% and 83%, respectively. They conclude that although specific, 3T fMRI, as currently used in the preoperative workup, is insufficiently sensitive for precise language mapping in patients with gliomas located in eloquent areas. Higher-grade tumors and tumors with higher rCBV significantly altered fMRI reliability.
fMRI performance varied in this study with oligodendrogliomas performing poorly, which the authors speculated may reflect neurovascular uncoupling, or other parameters such as glutamate recycling, pH modification or lactate production. They also showed a link between tumor grade and fMRI results, with high-grade tumors marginally associated with false negative occurrence. They also found that hyperperfused gliomas, (high tumor rCBV), were less likely to have fMRI false-positive occurrence.
2. Junck L, Hervey-Jumper SL, Sagher O. Resection of gliomas around language areas: Can fMRI contribute? Neurology. 2015;84:550–551. doi:10.1212/WNL.0000000000001241.
This editorial accompanies the Kuchcinshi paper, and compares and contrasts the strengths and weaknesses of fMRI and direct cortical stimulation (DCS). Notable limitations of DCS include inability of the patient to tolerate the awake evaluation during surgery, limited usefulness when there is underlying moderate or severe language impairment, and the risk of inducing seizures. Test results also vary with the strength of current used, with lower false-negatives with higher current, but with an increased risk of seizures.
3. Goel A. Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation. J Neurosurg Spine. 2015;22(February):116–127. doi:10.3171/2014.10.SPINE14176.
The author treated 65 patients over a three year period with Chiari malformation (CM). The surgical strategy of atlantoaxial fixation was performed in all cases regardless of any demonstrable evidence of craniovertebral instability or physical bone or joint abnormality. 55 patients had syringomyelia, and 37 patients basilar invagination. Sixty-three patients improved after surgery, and the improvement was sustained during the average follow-up period of 18 months. He concludes that the pathogenesis of CM with or without associated basilar invagination and/or syringomyelia is primarily related to atlantoaxial instability.
I don’t even know where to go with this paper. At a minimum, if you have a journal club, you should tackle the quality of the methods, variable patient population, and unconventional logic. The author concludes: “CM with or without basilar invagination, is always associated with instability at the atlantoaxial joint, even if such instability is not clinically manifest or is not demonstrated on radiological imaging” (my bold added).
What does that statement mean? The “instability” is present even if it can’t be observed by any radiologic means? How well validated is the presence of “instability” by manipulation in the OR? I think of the patients that he has shown (such as assimilation of C1 with occiput, basilar invagination, condylar and basioccipital hypoplasia) as having the primary defect being the congenital bony anatomy, with a secondary inferior displacement of the tonsils due to that abnormal anatomy, and not the primary abnormality being the CM.
4. Jea A. Editorial: Chiari malformation I surgically treated with atlantoaxial fixation. J Neurosurg Spine. 2015;22(2):113–115. doi:10.3171/2014.9.SPINE14893.
Interesting letter to the editor regarding the Goel paper, saying that the paper “challenges conventional theories”. Current and accepted pediatric neurosurgical literature shows an increased likelihood of fusion for patients with 1) basilar invagination, 2) CM 1.5, 3) clivoaxial angle <125 degrees. The author also calls the language used in the Goel paper “flowery and sophomoric”!
5. Huang Y, Kuo Y, Tseng Y, Chen D, Chiu W, Chen C. Susceptibility-weighted MRI in mild traumatic brain injury. Neurology. 2015;84:580–585.
The authors evaluated the frequency of microbleeds identified by susceptibility-weighted MRI (SWMRI) in patients with mild traumatic brain injury (mTBI) and normal controls, and correlate these findings with neuropsychological tests. They looked at 26 patients with mTBI and 12 control subjects presenting with microbleeds on SWMRI. The mTBI group showed more microbleeds in the cortex/subcortical region, and the control group showed more microbleeds in the central brain. mTBI patients who had microbleeds had lower digit span scores than the patients with negative SWMRI findings. They conclude that the presence of microbleeds could be a possible severity biomarker for mTBI.
They recommend the addition of SWMRI technique as a complementary sequence to the MRI protocol for patients with mTBI which will allow a nearly 25% increase in the detection rate of microbleeds.
6. Moses R a, Zhao W, Staub LP, Melloh M, Barz T, Lurie JD. Is the Sedimentation Sign Associated With Spinal Stenosis Surgical Treatment Effect in SPORT? Spine (Phila Pa 1976). 2015;40(3):129–136. doi:10.1097/BRS.0000000000000672.
The sedimentation sign is the position of the nerve roots within the thecal sac on the axial images; a negative sign being normal distribution to the dependent part of the canal, and the positive sign showing a more central position of the roots within the thecal sac. This reflects the stenosis that is present, which limits root displacement. In this study, the authors evaluated the 654 patients with spinal stenosis enrolled in Spine Patient Outcomes Research Trial. T2-weighted axial and sagittal digitized images of 115 patients were available for retrospective review. 66% of these patients had a positive sedimentation sign. A + sign was seen more often with stenosis at L2-3, and correlated with severe central stenosis at two or more levels. A positive sedimentation sign was associated with a small but significantly greater surgical treatment effect for Oswestry Disability Index in patients with symptomatic canal stenosis.
Every little bit helps. This is easy to evaluate, and is a reasonable addition to the usual morphologic evaluation we perform for canal stenosis. If this helps me avoid having to measure thecal sac surface area, I am all for it!
7. Nouri A, Tetreault L, Zamorano JJ, et al. Role of magnetic resonance imaging in Predicting Surgical Outcome in Patients with Cervical Spondylotic Myelopathy. Spine (Phila Pa 1976). 2015;40:171–178. doi:10.1097/BRS.0000000000000678.
278 patients with 1 or more clinical signs of myelopathy were enrolled; and they underwent decompression surgery. Complete baseline clinical and MRI data were available for 102 patients. Multivariate logistic regression was conducted after a conceptual division of variables into 3 groups: T1 signal analysis, T2 signal analysis, and anatomical measurements. The found that baseline clinical score (mJOA) was a strong predictor of postsurgical outcome in cervical spondylotic myelopathy at 6 months. A model inclusive of maximum canal compromise (MCC) and T1 hypointensity assessment provides superior predictive capacity.
For MCC definition, see: Fehlings MG et al., Spine 1999 ; 24: 605–13 . Take away is that MR has a significant role in predicting patient outcome.
8. Samuel S, Lin J, Smith MM, et al. Subaxial Injury Classification Scoring System Treatment recommendations. Spine (Phila Pa 1976). 2015;40(3):137–142. doi:10.1097/BRS.0000000000000666.
The authors defined the SLIC score by reviewing imaging studies and clinical records in 185 patients with subaxial cervical spine trauma presenting to a level 1 spinal injury referral center, and correlated them to the treatment decisions and surgical approach. The results showed that 94% of the nonsurgically managed patients and 96% of the surgically managed patients matched SLIC treatment recommendations. The mean SLIC score of the surgically treated group of patients was higher than that of the nonsurgical group. Injury morphology scores were not predictive of surgical approach, but increasing SLIC scores correlated with increasing complexity of treatment. They conclude that the use of SLIC as an ordinal severity scale is validated.
For more details on the scoring system, see: Vaccaro AR , Hulbert RJ , Patel AA , et al. The subaxial cervical spine injury classification system: a novel approach to recognize the importance of morphology, neurology, and integrity of the discoligamentous complex. Spine 2007; 32:2365–74 .
