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• Society for Neuro-Oncology

From the Literature Journal of Neurosurgery 97: 794, October 2002 Issue.

Histopathological validation of a three-dimensional magnetic resonance spectroscopy index as a predictor of tumor presence.

Mcknight et al. from the Departments of Radiology, Neurosurgery, and Radiation Oncology at UCSF.

In this article the authors examined the queston of whether the choline-NAA index (CNI) determined on MR spectroscopy could be used to detect metabolically active tumor in T2 hyperintense yet non-enhancing regions in patients with intrinsic brain tumors.  

The authors first used histologic criteria to generate a proposed cut-off for CNI to predict tumor versus non-tumorous tissue.  They found that in non-tumorous biopsies that the CNI was 1.7 while in Grade II, Grade III and Grade IV astrocytoma, this ratio was over 5.3. Using a CNI of 2.5, tumor could be distinguished from non-tumorous tissue with 90% specificity and 86% specificity.

Using this index, the authors then examined what percentage of MR defined lesion by T2 or T1 with constrast had a CNI greater than 2.5.  More than 1/3 of cases had CNI values consistent with tumor in the T2 intense region surrounding the contrast enhanced zone.

The authors also assessed heterogeneity of the CNI in the T2 hyperintense regions yet nonenhancing regions of Grade II, III, and IV astrocytomas.  In each of these grade tumors, >40% of the total T2 hyperintense, non enhancing volume had a CNI greater than 2.5. 

Commentary: The non-invasive detection of metabolically active tumor continues to be actively pursued as these authors describe.  One important implication of the current study is that it may be possible to target the most metabolically active regions of non-enhancing tumors as defined by a CNI ratio of >2.5.  These so called “MR defined hotspots” may be useful to improve the diagnostic yield in the biopsy of non-enhancing lesions.  ~Bob Carter, M.D., ~Fred Barker, M.D.

Hemicraniectomy remains an interesting and somewhat controversial topic as we continue to sort out which patient populations may most benefit.  The mortality benefit, even in the absence of controlled studies appears clear.  Recent reports are now beginning to look at morbidity following such large strokes.  This report addresses some of those questions…

Prognosis of patients after hemicraniectomy in malignant middle cerebral artery infarction.Walz B, Zimmermann C, Bottger S, Haberl RLWalz B, Zimmermann C, Bottger S, Haberl RLJ Neurol 2002 Sep;249(9):1183-90

Walz B, Zimmermann C, Bottger S, Haberl RLJ Neurol 2002 Sep;249(9):1183-90In the report, the authors looked at outcome in 18 patients who had undergone decompressive craniectomy. 6 patients died within 6 months of the procedure and 12 patients underwent more detailed follow-up studies.  The mean Barthel Index of survivors was 21.1  The Barthel average for those patients under 45 years was 75.5.  The authors also treated 5/18 patients with dominant hemispheric infarcts and noted “Fourr had a slight to moderate Broca aphasia and one patient a global aphasia. ”  11/12 survivors approved in retrospect the decision that had been made to proceed with hemicraniectomy.

Comments:  Hemicraniectomy continues to come more into the mainstream of neurosurgical practice.  Several studies have now shown that the Barthel Indices of populations of these patients can average over 60 and even better in younger patients.  More controversial remains the role of this procedure in dominant hemispheric infarcts.  At MGH, we have, in carefully selected patients (younger, with incomplete aphasia) have proceeded with dominant hemisphere decompression.  As more experience is gained with the procedure, we will further sort out those populations where most benefit is observed.  ~Bob Carter, M.D.

No Grand Rounds This Week….

Journal of Neurosurgery 2002 Sep;97(3):531-

Prediction of death in patients with primary intracerebral hemorrhage: a prospective study of a defined population.

Nilsson OG, Lindgren A, Brandt L, Saveland H. from the Lund University Department of Neurosurgery.

Summary:  The authors prospectively assessed those factors associated with 30 day and 1 year mortality in a population of patients with primary intracerebral hemorrhage.  In the 341 cases studied, the mortality rate was 36% at 30 days and 47% at one year.   Initial level of consciousness, hematoma volume, and heart disease were independent co-factors for early mortality.   Age was also a factor that predicted one year mortality. 72% of those with hematoma volume greater than 60 cc were deceased at 30 days whereas 19% of those with volume of less than 30 cc were deceased at 30 days. At the one year time point both deep and lobar hemorrhages had over 40% mortality.   

Commetary:  This report benefits from a prospective design, multivariate statistical analysis.  The emphasis on volume of hemorrhage and the level of consciousness are well warranted.  Greater than 80% of those who presented in coma were dead at 30 days.  What are the implications for the practicing neurosurgeon?  The question of when to evacuate intracerebral hematoma remains with us and these decisions must be made rapidly.  One advance would be software that would allow for segmentation and volume calculations proximate in time to the original CT scan.  To be called from the emergency room regarding a 57 cc hemorrhage in the occipital pole versus a 23 cc cerebellar hemorrhage would instantly convey important information about overall prognosis.  This would permit the development of clinical protocols that could be rapidly implemented for trials of minimally invasive evacuation or other therapies.   In conjuction with location data, this would allow us to go beyond the gestalt of “large” or “small” hemorrhages and be more quantitative.  ~Bob Carter, M.D.

Article Highlights

Neurosurgery 2002 Oct;51(4):939-43

Evaluation of vasospasm after subarachnoid hemorrhage by use of multislice computed tomographic angiography.

Otawara Y, Ogasawara K, Ogawa A, Sasaki M, Takahashi K.

Summary:  The authors performed multislice CTA and DSA on 20 patients with SAH within 72 hours of admission.  Multislice CTA and DSA were repeated on Day 7 to assess cerebral vasospasm. They showed that the degree of vasospasm as revealed by multislice CTA correlated significantly with the degree of vasospasm revealed by DSA (P < 0.0001). The level of agreement via CTA and DSA in the overall, proximal, and distal segments of the cerebral arteries was 91.6, 90.8, and 92.3%, respectively. The authors concluded that multislice CTA can detect angiographic vasospasm after SAH with accuracy equal to that of DSA.

Commentary:  The authors raise the question of whether multi-slice CTA can replace conventional angiography for the evaluation of vasospasm.  The article highlights the evolving role of CTA.  As image quality improves with CTA this modality may increasingly have a role as a screening modality prior to angiography.   Disadvantages of the technique occur in situations where clip or coil artifact obscure the vessel of interest and in the lack of being able to proceed directly to treatment.  Nonetheless, it may obviate angiography in cases where spasm can not be ruled out by other means.  ~B.Carter, M.D.

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