Caudal Anesthesia
Jean-Pierre Monnet, Yves Harmand in Pediatric Regional Anesthesia, 2019
Most surgical procedures of the lower part of the abdomen and lower extremities can be performed under caudal anesthesia. Some authors recommend caudal anesthesia for the cure of phimosis and for circumcision, while others recommend it for operations on the upper part of the abdomen. Caudal anesthesia is the regional block that should be considered first for operations on the lower part of the abdomen and on the pelvis. Lumbar epidural anesthesia was performed in children over 4 to 6 years of age, while caudal anesthesia was the rule for infants. Inadequate height of the block may also result from repetitive caudal anesthesias which may produce diminishing effects as they are repeated. The inadvertent misplacement of the tip of the caudal needle into the subarachnoid space will lead to spinal anesthesia. A complication is virtually impossible if the technique is properly achieved.
Analgesia
Kelvin Yan in Surgical and Anaesthetic Instruments for OSCEs, 2021
Spinal needles are inserted into the subarachnoid space at the lower lumbar level in order to provide a spinal anaesthetic. The layers of penetration of the spinal needle are the skin, subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, dura mater and arachnoid mater. The first spinal anaesthetic was performed by August Bier in 1898. The Whitacre needle features a pencil point tip which is thought to minimise the risk of post-puncture headache. The Quincke needle has a bevelled tip which cuts parallel to the dura fibres. Absolute contraindications include warfarinised patients, patients who have not stopped taking clopidogrel for at least 5 days before the procedure, coagulopathy, infection at the site of puncture, severe aortic stenosis and patient refusal. Relative contraindications include uncooperative patients and pre-existing neurological deficits. Post-procedural headaches and hypotension are fairly common side effects. The rest are uncommon but include bleeding, infection and neurological damage.
Blood–Brain Barrier and Cerebrospinal Fluid (CSF)
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
The blood–brain barrier is formed by the capillaries in the brain and prevents the free diffusion of circulating substances into the brain interstitial space. Capillary endothelial cells have the following distinct features: tight junctions (zona occludens) between adjacent cells, absence of fenestrations and a high content of mitochondria. The concentrations of calcium, magnesium and chloride ions in Cerebrospinal Fluid (CSF) are controlled by active transport mechanisms at the blood–brain barrier. Magnesium and chloride ions are present in higher concentrations in CSF than in plasma, suggesting transport of these ions across the blood–brain barrier by both passive and active mechanisms. CSF is formed in the brain by a combination of ultrafiltration and active secretion and circulates through the subarachnoid space and the ventricular system. As the choroid plexus epithelium is relatively impermeable because of the presence of apical tight junctions, ultrafiltration and secretion are important for the transport of selected constituents of the CSF.
Subarachnoid space diameter in chromosomally abnormal fetuses at 11–13 weeks’ gestation
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2019
Carolina Ferreira, Ana Lidia Rouxinol-Dias, Teresa Loureiro, Kypros Nicolaides
Objectives: To examine the subarachnoid space diameters in chromosomally abnormal fetuses at 11–13 weeks’ gestation. Methods: Stored three-dimensional (3D) ultrasound volumes of the fetal head at 11–13 weeks’ gestation from 407 euploid and 88 chromosomally abnormal fetuses (trisomy 21, n = 40; trisomy 18, n = 19; trisomy 13, n = 7; triploidy, n = 14; Turner syndrome, n = 8) were analyzed. The subarachnoid space diameters, measured in the sagittal and transverse planes of the fetal head, in relation to biparietal diameter (BPD) in each group of aneuploidies was compared to that in euploid fetuses. A total of 20 head volumes were randomly selected and all the measurements were recorded by two different observers to examine the interobserver variability in measurements. Results: In euploid fetuses, the anteroposterior, transverse and sagittal diameters of the subarachnoid space increased with BPD. The median of the observed to expected diameters for BPD were significantly increased in triploidy and trisomy 13 but were not significantly altered in trisomies 21 and 18 or Turner syndrome. In triploidy, the subarachnoid space diameters for BPD were above the 95th centile of euploid fetuses in 92.9% (13 of 14) cases. The intraclass reliability or agreement was excellent for all three subarachnoid space diameters. Conclusion: Most fetuses with triploidy at 11–13 weeks’ gestation demonstrate increased subarachnoid space diameters.
Fetal wide subarachnoid space and its outcome in cases of macrocephaly without ventriculomegaly
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2020
Joel Baron, Salvatore Andrea Mastrolia, Ilan Shelef, Dan Tirosh, Analia Mijalovsky, Yigal Ben-Harush, Reli Hershkovitz
Objective: To examine the occurrence and outcomes of fetuses with wide subarachnoid space (WSS) without ventriculomegaly in pregnant women with fetal macrocephaly as a sole diagnosis. Study design: A retrospective study was performed, analyzing patients with fetal macrocephaly between the years 2008 and 2018. All these patients underwent MRI, in order to detect brain anomalies. In the absence of any other brain abnormality, they were evaluated for WSS and their offspring’s database was followed for at least two years after birth. Results: Ten patients were found to be carrying fetuses with macrocephaly, nine of them were diagnosed with WSS without ventriculomegaly prior to delivery. Following at least two years of follow up, all patients did not present significant neurodevelopmental abnormalities, apart from one child that had a genetic mutation of 15q21.2-22.31 deletion with other anomalies that were not diagnosed prenatally. Conclusions: We present herein for the first time in the literature a cohort of patients with a prenatal diagnosis of WSS without ventriculomegaly in fetuses with macrocephaly. Our data show that, in the presence of normal anomaly scan and normal chromosomal study, there is a low chance for significant neurodevelopmental abnormalities in fetuses with WSS without ventriculomegaly.
A new shunt for obstructive hydrocephalus: ventricle-Sylvian fissure shunt
Published in British Journal of Neurosurgery, 2017
Cerbrospinal fluid (CSF) pathway studies have revealed that after egressing from the fourth ventricle reaches the basal supra sellar cistern and ultimately the sylvian cisterns from where the CSF travels over the cerebral convexity subarachnoid space to reach the superior saggital sinus and enters the blood stream. Diverting CSF from the lateral ventricle with a shunt catheter to the sylvian cistern can be an option to treat obstructive hydrocephalus. 2 patients underwent this procedure of diverting CSF from the lateral ventricle with a shunt catheter (Chabbra, India) to the sylvian cistern successfully and had immediate relief of symptoms of raised intracranial pressure. Additional 4 patients had relief for 3mths to 6 mths and are under follow up. Though preliminary results seem logical and promising, more cases and longer follow-up is required to consider this shunt operation as an option in treatment of obstructive hydrocephalus.