Discussions (D)
Terence R. Anthoney in Neuroanatomy and the Neurologic Exam, 2017
As noted in the discussion of Semantic Conflict 1, most authors of recent texts define the brain stem as consisting of the midbrain, pons, and medulla oblongata. Consequently, the fourth ventricle is not the only relevant cerebrospinal-fluid(CSF)-containing cavity; the cerebral aqueduct and the central canal in the caudal medulla also need to be considered. In cross-sections of the brain stem, however, the latter two cavities (unlike the fourth ventricle) are completely surrounded by structures generally agreed upon as belonging to the brain stem. As a result, recent texts uniformly describe the cerebral aqueduct and central canal of the medulla as being in the brain stem. Nevertheless, being in the brain stem does not necessarily mean being part of the brain stem, as is made clear by the rare statement that excludes all CSF-containing cavities from the CNS (see D: Ventricular system for sample quotation and source). Otherwise, however, the cerebral aqueduct and central canal of the medulla are almost always described as if they are part of the brain stem.
The patient with acute neurological problems
Ian Peate, Helen Dutton in Acute Nursing Care, 2014
CSF flows from the two lateral ventricles into the third ventricle where another choroid plexus generates more CSF. CSF then flows through the cerebral aqueduct, or aqueduct of Sylvius, into the fourth ventricle where further CSF is generated. The CSF then enters the subarachnoid space, the space between the arachnoid mater and the pia mater, through openings in the ceiling of the fourth ventricle. CSF circulates in the subarachnoid space around the brain and spinal cord and also in the central canal of the spinal cord. CSF is absorbed back into the blood by arachnoid villi, finger-like projections of the arachnoid mater. If the volume of the CSF is to remain constant then the CSF must be produced and reabsorbed at the same rate. Once generated the CSF should flow unobstructed from the ventricles through the arachnoid space and into the spinal canal. The flow of CSF can be affected by tumours, inflammatory conditions like ventriculitis and by intraventricular or subarachnoid haemorrhage which can cause CSF flow to become obstructed by thrombus. If this happens CSF continues to be produced but cannot drain adequately and the pressure of the CSF increases: this clinical condition is termed hydrocephaly Hydrocephaly can be controlled temporarily by the insertion of an extra-ventricular drain (EVD) or permanently by the insertion of a ventricular–peritoneal (VP) shunt. Because adult skull bones are fused any increase in CSF pressure will result in an increase in intracranial pressure (ICP) and is a clinical emergency.
Anatomy of the head and neck
Helen Whitwell, Christopher Milroy, Daniel du Plessis in Forensic Neuropathology, 2021
The cerebral aqueduct traverses the length of the midbrain ventral to the colliculi, with the trochlear and oculomotor cranial nerve nuclei located adjacent to it within the periaqueductal grey matter. At the level of the inferior colliculus, the superior cerebellar peduncles are related to the central portion of the tegmentum. Ventrally, the midbrain tegmentum is the site of the substantia nigra, consisting in part of pigmented, melanin-containing neurons that synthesise dopamine as their transmitter. It is degeneration of the substantia nigra that is associated with Parkinson's disease and problems secondary to drug abuse. Anterior to the substantia nigra are the large crus cerebri, composed entirely of the descending cortical efferent fibres that have passed through the internal capsule after leaving the cerebral hemispheres. Sections through the brainstem are illustrated in Figure 1.9a–e.
Andreas Vesalius of Brussels (1514–1564): his contribution to the field of functional neuroanatomy and the criticism to his predecessors
Published in Acta Chirurgica Belgica, 2020
Konstantinos Markatos, Dimitrios Chytas, Georgios Tsakotos, Marianna Karamanou, Maria Piagkou, Antonios Mazarakis, Elizabeth Johnson
Until the fifteenth century, the knowledge about the anatomy of brain had been significantly affected by theological implications. Vesalius, who was based on humans’ brain dissections, criticized his predecessors and introduced new data regarding brain anatomy and function. Specifically, the pre-Vesalius era the intellectual activities were considered to derive from the brain’s ventricles which were three or four and usually spherical [6]. Vesalius firstly introduced an anatomical accurate and systematic description of the humans’ brain ventricles. The anterior ventricle was correlated with imagination and perception, the middle ventricle was the region of judgment and cogitation and the posterior ventricle was correlated with memory [2]. He also criticized the widely accepted opinion that the brain’s ventricles are correlated with mental activities and are activated by the flow of the animal spirit [11–13], although he refuted the influence of the animal spirit on mental activities [11,12]. Vesalius supported that function remained located into the ventricle and this is why his anatomical interest was concentrated on their walls. He described the corpus callosum, as the roof of the lateral ventricle joining the right and left hemispheres.Also he depicted the fornix, as the roof of the third ventricle despite the technical difficulties in non-fixed dissected brains. Similarly, he depicted the structures located around the cerebral aqueduct and the fourth ventricle. The white and gray matter was only partially described by Vesalius and no information was provided in his book concerning their function (Figure 2) [13].
A rare case of intralesional haemorrhage of a benign aqueductal cyst after CSF diversion treatment. A case report and review of literature
Published in British Journal of Neurosurgery, 2023
R. D. Biju, J. O’ Sullivan, A. Thomas, P. Gan, T. Muthu
The natural history of benign ventricular cysts is poorly understood.5,6 Colloid cysts are rare, representing about 0.5–1% of all intracranial tumours.7,8 Preferentially encountered within the third ventricle, other locations have been reported including the fourth ventricle, suprasellar region, cerebellum and rarely, within the cerebral aqueduct.9 They are not typically vascular in nature, making intracystic haemorrhage a rare phenomenon. About 21 cases have been reported in literature worldwide, 4 of which were at post-mortem.10,11 Cuoco et al. hypothesized that an exercise-induced rise in systolic blood pressure contributed to the phenomena in their 21-year-old patient.12 Spontaneous intracystic haemorrhage in pineal cysts is a well-documented phenomenon. Tamura et al. described its occurrence in their patient who commenced antiplatelet treatment for stroke.13,14
Coats plus in prematurity
Published in Ophthalmic Genetics, 2022
Ashley López-Cañizares, Maria P. Fernandez, Hasenin Al-Khersan, Piero Carletti, Monica S Arroyo, Maria C Fernandez-Ruiz, Audina M Berrocal
At this juncture, given the established family history along with the atypical behavior of Patient 1ʹs retinopathy, and his complex medical history, the case was discussed with the pediatric neurologist, and neuroimaging was recommended. Computed tomography (CT) scan and magnetic resonance imaging (MRI) of the brain demonstrated bilateral calcifications involving the gray-white matter interface, thalami, and bilateral basal ganglia. Disease involvement of the quadrigeminal plate, which appeared thickened and irregular, was associated with narrowing of the cerebral aqueduct and obstructive hydrocephalus, with mild-to-moderate dilatation of the lateral and third ventricles. Genetic testing was then pursued, which revealed two heterozygous pathogenic mutations in the CTC1 gene: c.2954_2956del (p.Cys985del) and c.859C>T (p.Arg287), confirming the diagnosis of Coats Plus syndrome in Patient 1 as well.