Cerebral Blood Flow in Low Intracranial Pressure Headaches-What is Known?

Management of sporadic intracranial vascular malformations in pregnancy: a retrospective analysis

BACKGROUND

Sporadic intracranial vascular malformations can pose significant risk to parturients, and additional reports of management may inform patient care. Here we describe the peripartum management of parturients with intracranial vascular malformations.

METHODS

After Institutional Review Board approval, we performed a retrospective analysis of parturients with a known sporadic intracranial vascular malformation including cavernous malformation, developmental venous anomaly, or arteriovenous malformation who delivered at our institution between 2007 and 2020.

RESULTS

We identified 10 parturients (five cavernous malformations, three developmental venous anomalies, and two arteriovenous malformations) with 16 deliveries. Among all deliveries, 13 (81.3%) were cesarean deliveries without trial of labor; 11 of these (84.6%) received a single-shot spinal and two (15.4%) received an epidural for surgical anesthesia. Two deliveries (12.5%) began with attempted trial of labor but ultimately required cesarean delivery for failure to progress; one of these cases received epidural anesthesia and the other received combined spinal-epidural anesthesia. One delivery was via spontaneous vaginal delivery with epidural analgesia. Overall, our study's cesarean delivery rate was 93.8% and spontaneous vaginal delivery rate was 6.2%. Three of 16 pregnancies were complicated by seizure, obstructive hydrocephalus, or intracranial hemorrhage. There were no intensive care unit admissions or maternal deaths.

CONCLUSIONS

In our case series of 16 deliveries, there were no complications directly resulting from neuraxial procedures. It remains unclear whether intracranial developmental venous anomalies or unruptured arteriovenous malformations impart increased risk during pregnancy. Antepartum planning with a multidisciplinary team approach enables risk stratification and optimal management.

The relationship between myodural bridge, atrophy and hyperplasia of the suboccipital musculature, and cerebrospinal fluid dynamics

The Myodural Bridge (MDB) is a physiological structure that is highly conserved in mammals and many of other tetrapods. It connects the suboccipital muscles to the cervical spinal dura mater (SDM) and transmits the tensile forces generated by the suboccipital muscles to the SDM. Consequently, the MDB has broader physiological potentials than just fixing the SDM. It has been proposed that MDB significantly contributes to the dynamics of cerebrospinal fluid (CSF) movements. Animal models of suboccipital muscle atrophy and hyperplasia were established utilizing local injection of BTX-A and ACE-031. In contrast, animal models with surgical severance of suboccipital muscles, and without any surgical operation were set as two types of negative control groups. CSF secretion and reabsorption rates were then measured for subsequent analysis. Our findings demonstrated a significant increase in CSF secretion rate in rats with the hyperplasia model, while there was a significant decrease in rats with the atrophy and severance groups. We observed an increase in CSF reabsorption rate in both the atrophy and hyperplasia groups, but no significant change was observed in the severance group. Additionally, our immunohistochemistry results revealed no significant change in the protein level of six selected choroid plexus-CSF-related proteins among all these groups. Therefore, it was indicated that alteration of MDB-transmitted tensile force resulted in changes of CSF secretion and reabsorption rates, suggesting the potential role that MDB may play during CSF circulation. This provides a unique research insight into CSF dynamics.

An anatomical study of the suboccipital cavernous sinus and its relationship with the myodural bridge complex

The suboccipital cavernous sinus (SCS) and the myodural bridge complex (MDBC) are both located in the suboccipital region. The SCS is regarded as a route for venous intracranial outflow and is often encountered during surgery. The MDBC consists of the suboccipital muscles, nuchal ligament, and myodural bridge and could be a power source for cerebrospinal fluid circulation. Intracranial pressure depends on intracranial blood volume and the cerebrospinal fluid. Since the SCS and MDBC have similar anatomical locations and functions, the aim of the present study was to reveal the relationships between them and the detailed anatomical characteristics of the SCS. The study involved gross dissection, histological staining, P45 plastination, and three-dimensional visualization techniques. The SCS consists of many small venous sinuses enclosed within a thin fibrous membrane that is strengthened by a fibrous arch closing the vertebral artery groove. The venous vessels are more abundant in the lateral and medial portions of the SCS than the middle portion. The middle and medial portions of the SCS are covered by the MDBC. Type I collagen fibers arranged in parallel and originating from the MDBC terminate on the SCS either directly or indirectly via the fibrous arch. The morphological features of SCS revealed in this research could serve as an anatomical basis for upper neck surgical procedures. There are parallel arrangements of type I collagen fibers between the MDBC and the SCS. The MDBC could change the blood volume in the SCS by pulling its wall during the head movement.

Predictors Associated with Outcomes of Epidural Blood Patch in Patients with Spontaneous Intracranial Hypotension

An autologous epidural blood patch (EBP) is a mainstay of treatment in patients with spontaneous intracranial hypotension (SIH). EBP, however, is less effective for SIH than post-dural puncture headaches. Therefore, patients with SIH frequently require an additional EBP. The aim of this study was to identify factors associated with poor response to EBP. This single-center retrospective observational study used the institutional registry records of 321 patients who underwent EBP between September 2001 and March 2016. Patients were divided into two groups, a poor responder group, consisting of patients who underwent EBP at least three times or more, and a good responder group of patients who experienced sufficient symptom relief after two or fewer EBP. The demographic characteristics, clinical features, radiologic findings, procedural data, and laboratory data were analyzed. Univariate analysis showed that the neutrophil-to-lymphocyte ratio (NLR; p = 0.004) and platelet-to-lymphocyte ratio (p = 0.015) were significantly lower in poor than in good responders. Multivariate analysis found that NLR was the only independent factor associated with a poor response (odds ratio = 0.720; p = 0.008). These findings indicate that a low NLR was associated with three or more EBP administrations for the sufficient improvement of symptoms in patients with SIH.

The Association of Acute Cerebrospinal Fluid Pressure Reduction with Choroidal Thickness

PURPOSE

To investigate the changes in choroidal thickness (CT) after acute cerebrospinal fluid pressure (CSFP) reduction in human subjects.

METHODS

Before and 15 minutes after diagnostic lumbar puncture (LP), 44 patients underwent measurement of CT by swept-source optical coherence tomography. Thirty-two healthy volunteers imitated the body posture of LP procedure and underwent the same measurement before and 15 minutes after body posture change.

RESULTS

After CSFP reduction from 10.9 ± 2.1 mmHg at baseline to 8.1 ± 1.5 mmHg (p < 0.001), CT decreased in subfoveal region (p = 0.005), small to medium vessel layer (SMVL, p < 0.001), peripapillary regions in temporal (p = 0.001), nasal (p < 0.001), superior (p < 0.001) and inferior (p < 0.001), respectively. However, no significant change in CT in the control group after body posture change (all p > 0.05). A significant association between CSFP and the ratio of small to medium vessel layer to total choroidal thickness was found (p = 0.009). The CSFP reduction rate was associated with the change rate of SMVL to total CT portion, for each percent decrease in CSFP was associated with a decrease by 0.22% in the rate of SMVL to total CT portion (R² = 0.125, p = 0.018).

CONCLUSIONS

A significant decrease in subfoveal CT, small to medium vessel layer and peripapillary region were observed following acute CSFP reduction. The CSFP reduction rate was associated with the change rate of small to medium vessel layer to total CT portion.