Monitoring of venous blood flow velocity during interhemispheric approach for deep seated lesions

The Superficial Anastomosing Veins of the Human Brain Cortex: A Microneurosurgical Anatomical Study

Introduction: In this microneurosurgical and anatomical study, we characterized the superficial anastomosing veins of the human brain cortex in human specimens.

Material and Methods: We used 21 brain preparations fixed in formalin (5%) that showed no pathological changes and came from the autopsy sections. The superficial veins were dissected out of the arachnoid with the aid of a surgical microscope.

Results: We dissected nine female and 12 male brain specimens, with an average age of 71 ± 11 years (range 51–88 years). We classified the superficial veins in five types: (I) the vein of Trolard as the dominat vein; (II) the vein of Labbé as the dominant vein; (III) a dominant sylvian vein group, and the veins of Trolard and Labbé nonexistent or only rudimentary present without contact to the Sylvian vein group; (IV) very weak sylvian veins with the veins of Trolard and Labbé codominant; and V) direct connection of Trolard and Labbé bypassing the Sylvian vein group. The vein of Trolard was dominant (Type I) in 21.4% and the vein of Labbé (Type II) in 16.7%. A dominant sylvian vein group (Type III) was found in 42.9%. Type IV and Type V were found in 14.3 and 4.7% respectively.

Conclusion: No systematic description or numerical distribution of the superior anastomotic vein (V. Trolard) and inferior anastomotic vein (V. Labbé) has been found in the existing literature. This study aimed to fill this gap in current literature and provide data to neurosurgeons for the practical planning of surgical approaches.

Intraoperative utilization of Microvascular Doppler for the detection of intracranial venous structures during tumor resection - A technical note

BACKGROUND

Microvascular Doppler (MVD) has been widely used for the detection of arterial blood flow in the brain, especially during aneurysm clipping, vascular malformation resection, or bypass surgeries. However, the benefits obtained from early identification of intracranial sinuses and deep draining veins during tumor resection has not been reported.

METHODS

We reviewed the clinical data and imaging from our cases and conducted a systemic review of the medical literature using PubMed and keywords. Bibliographies of each result were evaluated to determine if additional reports describing the use of MVD during tumor resection could be found.

RESULTS

No reports were found in the literature where MVD was specifically used for venous identification during the resection of deep-seated brain tumors. In our patient cohort, MVD was used successfully to detect and ultimately allow immediate protection of large dural venous sinuses as well as smaller deep cerebral veins during tumor resection. Each patient developed no new venous infarcts and made a satisfactory recovery with no new postoperative neurological deficits.

CONCLUSION

MVD is a reliable tool for the intraoperative detection of intracranial venous blood flow to allow for quick identification and protection of venous structures. MVD is an additional safety measure for the patient as its accuracy in detecting venous structures is less susceptible to many of the inherent weaknesses of stereotactic neuro-navigation including the accompanying brain shift or anatomical distortion produced by long duration deep seated brain tumor resection.

Real-Time Ultrasound Doppler Enhances Precision in Image-Guided Approaches to the Cerebellopontine Angle

OBJECTIVE

To evaluate efficacy and reliability of intraoperative Doppler sonography in localizing the transverse and sigmoid sinuses during lateral suboccipital craniotomy.

METHODS

A 16-Mhz intraoperative micro-Doppler ultrasound (16Mhz, Multi-Dop pro, Compumedics, Singen, Germany) was applied to detect the medial border of the sigmoid sinus and the inferior border of the transverse sinus in 25 patients. Micro-Doppler measurements were compared with magnetic resonance- and computed tomography-based image guidance (Kolibri, Brainlab, Munich, Germany). Visual detectability of the sinuses with the operating microscope was also documented.

RESULTS

Inadvertent incision of the transverse or sigmoid sinuses did not occur in any patient when the 2 localizing methods have been used in combination. The mean mismatch of image-guided system and micro-Doppler was 2.64 mm (range, 0-6 mm; standard deviation, 1.55 mm). With the microscope the transverse sinus was invisible in 7 patients, the sigmoid sinus was visually undetectable in 1 case. The micro-Doppler indicated blood flow outside the visible borders of the sinuses in 5 patients.

CONCLUSIONS

A combination of image-guidance and micro-Doppler enhances the accuracy in localizing the margins of the transverse and sigmoid sinuses using the retrosigmoid approach, thus preventing inadvertent injury. The method could potentially be applied during other craniotomies involving the exposure of a venous sinus.

The intracranial bridging veins: a comprehensive review of their history, anatomy, histology, pathology, and neurosurgical implications

INTRODUCTION

The intracranial bridging veins are pathways crucial for venous drainage of the brain. They are not only involved in pathological conditions but also serve as important landmarks within neurological surgery.

METHODS

The medical literature on bridging veins was reviewed in regard to their historical aspects, embryology, histology, anatomy, and surgery.

CONCLUSION

Knowledge on the intracranial bridging veins and their dynamics has evolved over time and is of great significance to the neurosurgeon.

Investigating the possibility and probability of perinatal subdural hematoma progressing to chronic subdural hematoma, with and without complications, in neonates, and its potential relationship to the misdiagnosis of abusive head trauma

The high incidence of subdural hematoma (SDH) from birthing was first identified with MRI by Looney in 2007 and was then more accurately determined by Rooks in 2008. Rooks screened 101 "normal" deliveries and demonstrated that 46% of the babies in her series and by inference, approximately 46% of the 4 million born normally in the US have SDH that formed in the perinatal (birthing) period during labor. Both metabolic strain and physical forces exerted on the head damage the capillaries within the dura (the intradural capillary bed), which is the source of the blood in the SDH that results from labor and delivery or at times from labor alone. While child abuse pediatricians relying on Rooks, maintain that no permanent complications result, her study was limited to 101 subjects and the sole criteria for resolution was the resolution of the SDH as seen on follow-up MRI. In fact, Rooks did have one patient (1%) who had complications that lead to symptoms and findings often associated with abuse. The purpose of this article is to explore if there is a complication rate for perinatal (PSDH) that supports that 1% of complications that are definable by different criteria. Next, if there are complications, how many of the roughly 2,000,000 cases of perinatal acute subdural hematoma every year in the United States will suffer them? Then, what are the clinical manifestations of the complications if they occur? Lastly, do the complications cause or mimic some or all of the findings that are offered by board certified child abuse pediatricians as evidence of child abuse? The article argues that a small percentage, but significant number of neonates, suffer birth related complications and findings secondary to the development of chronic subdural hematoma CSDH) that are often misdiagnosed as abusive head trauma.

Is exposure of the superior sagittal sinus necessary in the interhemispheric approach?

OBJECTIVE

Techniques for anterior interhemisperic craniotomy vary in respect to the degree of exposure of the superior sagittal sinus (SSS). The aim of this anatomic study is to quantify the increase in the angle of view gained by wide exposure and retraction of the SSS.

METHODS

The anterior interhemispheric approach was performed in 10 cadaveric specimens with and without complete exposure and retraction of the SSS. Prespecified anatomic targets within the depth of the surgical field were used to calculate the angle of view.

RESULTS

Complete exposure of the SSS in the anterior interhemispheric approach, increased the angle of view from 20.6 +/- 3 to 26.8 degrees, using the A4-A5 junction as a deep anatomic target (P = 0.008). When the free edge of the falx was considered as a deep anatomic target, complete exposure of the SSS increased the working angle from 34 +/- 3.14 to 42.1 +/- 4 (P = 0.0004).

CONCLUSION

In this study, we demonstrate a significant increase in the angle of view after complete exposure of the SSS, targeting either deep (anterior cerebral artery) or more shallow structures (free falx edge).

Transcranial ultrasonography of cerebral veins and sinuses

Transcranial ultrasonography has become a valuable diagnostic tool for the bed-side evaluation of cerebral hemodynamics. While the assessment of arterial blood flow is well established, analysis of venous hemodynamics by transcranial ultrasonography is a new application of the method. The present review summarises the current state of transcranial venous ultrasound in adults by means of transcranial Doppler (TCD) and transcranial colour-coded duplex sonography (TCCS). It gives a critical overview regarding current and possible future clinical applications of the techniques.

Impairment of autoregulation following cortical venous occlusion in the rat

Recent experiments showed an upward shift of the lower limit of autoregulation (AR) following photochemical occlusion of cortical veins in the rat. The goal of the present study was to prove the hypothesis that occlusion of cortical veins will be associated with impairment of the upper limit of autoregulation as well. In n = 28 Wistar rats unilateral frontoparietal cranial windows were drilled for transdural assessment of regional cerebral blood flow (rCBF) by laser Doppler scanning. The animals were allotted to two groups: (1) Group A (n = 5), control group for determination of the upper limit of autoregulation with stepwise induced arterial hypertension by intravenous administration of the alpha adrenergic drug methoxamine under continuous monitoring of mean arterial blood pressure (MABP); (2) Group B (n = 23), in which two cortical veins were photochemically occluded with rose bengal dye and fiberoptic illumination upon baseline CBF measurement. This was followed by repeated rCBF measurements under AR testing. Loss of AR in control Group A with passive increase of rCBF occurred at MABP of 147.5 +/- 2.9 mmHg. In Group B venous occlusion was followed by an initial phase of reduced rCBF, and then by pressure passive increases, thereby indicating loss of AR. Statistically significant changes of rCBF when compared to baseline MABP occurred at MABPbaseline + 10% (112.7 +/- 6.6 mmHg). We conclude that AR is impaired upon cortical venous occlusion with the propensity for hyperperfusion injury at a lower level of MABP when compared with a control group. In the context with earlier findings this may lead to narrowing of the corridor for MABP management following intra-operative occlusion of large cortical veins.