Increase in Brain Volume After Aneurysmal Subarachnoid Hemorrhage Leads to Unfavorable Outcome: A Retrospective Study Quantified by CT Scan

Background and Purpose: Primary brain swelling occurs in aneurysmal subarachnoid hemorrhage (aSAH) patients. The absence of a dynamic quantitative method restricts further study of primary brain swelling. This study compared differences in the change rate of brain volume (CRBV) between patients with and without primary brain swelling in the early stage of aSAH. Moreover, the relationship between CRBV and clinical outcomes was evaluated.Methods: Patients hospitalized within 24 h after aSAH were included in this retrospective study. Utilizing a qualitative standard established before the study to recognize primary brain swelling through brain CT after aSAH, clinical outcomes after 3 months of SAH were evaluated with a modified Rankin scale (mRS). The brain volume (BV) of each patient was calculated with a semiautomatic threshold algorithm of 3D-slicer, and the change in brain volume (CIBV) was obtained by subtracting the two extreme values (CIBV = BVmax – BVmin). The CRBV was obtained by CIBV/BVmin × 100%. The CRBV values that predicted unfavorable prognoses were estimated.Results: In total, 130 subjects were enrolled in the study. The mean CRBV in the non-swelling group and swelling group were 4.37% (±4.77) and 11.87% (±6.84), respectively (p < 0.05). CRBV was positively correlated with the length of hospital stay, blood in the ambient cistern, blood in the lateral ventricle, and lateral ventricular volume (Spearman ρ = 0.334; p < 0.001; Pearson ρ = 0.269, p = 0.002; Pearson ρ = 0.278, p = 0.001; Pearson ρ = 0.233, p = 0.008, respectively). Analysis of variance showed significant differences in CIBV, CRBV, blood in the ambient cistern, blood in the lateral ventricle, and lateral ventricular volume among varying modified Fisher scale (mFisher), with higher admission mFisher scale, indicating larger values of these variables. After adjusting for risk factors, the model showed that for every 1% increase in the CRBV, the probability of poor clinical prognosis increased by a factor of 1.236 (95% CI = 1.056–1.446). In the stratified analysis, the odds of worse clinical outcomes increased with increases in the CRBV. Receiver operating characteristic curve analysis showed that HH grade, mFisher scale, and score of CRBV (SCRBV) had diagnostic performance for predicting unfavorable clinical outcomes.Conclusion: Primary brain swelling increases brain volume after aSAH. The CRBV quantified by 3D-Slicer can be used as a volumetric representation of the degree of brain swelling. A larger CRBV in the early stage of aSAH is associated with poor prognosis. The CRBV can be used as a neuroimaging biomarker of early brain injury after bleeding and may be an effective predictor of patients' clinical prognoses.

Meningioma of posterolateral tentorial incisura: a case demonstration of paramedian supracerebellar transtentorial approach

The paramedian supracerebellar transtentorial approach allows unobstructed exposure to the quadrigeminal cistern, tectal plate, pineal region, tentorial incisura, medial basal temporal lobe, and posterior ambient cistern. The authors present a meningioma of the posterolateral tentorial incisura case in a 62-year-old male who presented with a long history of upper-extremity tremors and walking difficulties. MRI revealed supra- and infratentorial tumor extension and hydrocephalus. This approach enabled us to achieve gross-total resection without causing neurovascular injury or any postoperative neurological deficits. For each pathology, the pros and cons of various approaches should be considered based on the anatomy, vasculature, and any surrounding structures. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2138.

Microsurgical and Tractographic Anatomical Study of Transtemporal-Transchoroidal Fissure Approaches to the Ambient Cistern

BACKGROUND Approaching ambient cistern lesions is still a challenge because of deep location and related white matter tracts (WMTs) and neural structures. OBJECTIVE To investigate the white matter anatomy in the course of 3 types of transtemporal-transchoroidal fissure approaches (TTcFA) to ambient cistern by using fiber dissection technique with translumination and magnetic resonance imaging fiber tractography. METHODS Eight formalin-fixed cerebral hemispheres were dissected on surgical corridor from the temporal cortex to the ambient cistern by using Klingler's method. The trans-middle temporal gyrus, trans-inferior temporal sulcus (TITS), and trans-inferior temporal gyrus (TITG) approaches were evaluated. WMTs that were identified during dissection were then reconstructed on the Human Connectome Project 1021 individual template for validation. RESULTS The trans-middle gyrus approach interrupted the U fibers, arcuate fasciculus (AF), the ventral segment of inferior frontoocipital fasciculus (IFOF), the temporal extensions of the anterior commissure (AC) posterior crura, the tapetum (Tp) fibers, and the anterior loop of the optic radiation (OR). The TITS approach interrupted U fibers, inferior longitudinal fasciculus (ILF), IFOF, and OR. The TITG approach interrupted the U fibers, ILF, and OR. The middle longitudinal fasciculus, ILF, and uncinate fasciculus (UF) were not interrupted in the trans-middle gyrus approach and the AF, UF, AC, and Tp fibers were not interrupted in the TITS/gyrus approaches. CONCLUSION Surgical planning of the ambient cistern lesions requires detailed knowledge about WMTs. Fiber dissection and tractography techniques improve the orientation during surgery and may help decrease surgical complications.

Supracerebellar Infratentorial Approach for Complex Thalamic Cavernous Malformation: 2-Dimensional Operative Video

Key points for the approach include the use of a supracerebellar infratentorial craniotomy, dynamic and gravity retraction, lighted bipolar forceps and suction, and stereotactic navigation. This patient has a large cavernous malformation extending from the midbrain to the thalamus in craniocaudal extent. The cavernous malformation extends to the midbrain surface along the interface with the ambient cistern, making it appropriate for the supracerebellar infratentorial approach. By cutting the tentorium access to the superior extension becomes feasible. The cavernous malformation is excised in a piecemeal manner utilizing a CO2 laser. Because removal of the large mass allowed the partial collapse of the cavity, a small segment of the cavernous malformation obscured by the collapse is retained cranially along the foramen of Monro. This situation required a return to the operating room for complete excision. The patient tolerated both procedures well and remained at her neurological baseline postoperatively. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. The surgical video has been used with permission from the Barrow Neurological Institute.

Transarterial and transvenous approaches for embolization of tentorial dural arteriovenous fistula

Tentorial dural arteriovenous fistulas (DAVFs) are uncommon, complex fistulas located between the leaves of the tentorium cerebelli with a specific anatomic and clinical presentation characterized by high hemorrhagic risk. They have an extensive arterial supply and complex venous drainages, making them difficult to treat. There is recent literature favoring treatment through an endovascular transarterial route. The authors present an uncommon tentorial/ambient cistern region DAVF with feeders arising from the external and internal carotid arteries. The patient underwent a combined transarterial and transvenous approach with successful obliteration of the DAVF. The authors discuss the management challenges faced in this case.The video can be found here: https://youtu.be/VXDD8zUvsSQ.