Meningioma
Dongyou Liu in Tumors and Cancers, 2017
As the membranous coverings of the brain and spinal cord, the meninges are composed of three layers: the dura mater, arachnoid mater, and pia mater. The dura mater (or the pachymeninges) is the outermost, thick, tough, and inextensible layer situated beneath the bones of the skull and vertebral column. The arachnoid mater is the middle layer lying underneath the dura mater. Small projections of the arachnoid mater into the dura (known as arachnoid granulations) allow cerebrospinal fluid (CSF) contained in the subarachnoid space to reenter the circulation via the dural venous sinuses. The pia mater is the inner layer that lies below the subarachnoid space. As the only covering to follow the contours of the brain (the gyri and fissures), the pia mater is very thin, vascular, and fibrous and adheres tightly to the surface of the brain and spinal cord. Collectively, the arachnoid mater and the pia mater are often referred to as the leptomeninges.
Neonatal Bacterial Infection
K. Balamurugan, U. Prithika in Pocket Guide to Bacterial Infections, 2019
Meningitis is a neurologic emergency characterized by inflammation of the meninges in response to microbial infection (Heckenberg 2014). The hallmark feature of meningitis is the inflammation in pia matter, arachnoids, and subarachnoid space. Moreover, some forms of neurological sequelae in neonatal meningitis have been associated with deficit in learning and memory due to prominent neuronal injury or damage in the two brain structures, namely the cortex and the hippocampus (Bifrare et al. 2003; Leib et al. 2003; Blaser 2011; Barichello et al. 2013a, 2013b). Sepsis is defined as the systemic response to infection. The infection manifests two or more clinical symptoms, including changes in body temperature (>38˚C or <36˚C), heart rate (>90 beats/min), respiratory rate (>20 breaths/min) or partial CO2 (<32 mm Hg), and white blood cell (>12,000/cu mm or <4,000/cu mm). Severe sepsis condition causes hypotension and multiple organ dysfunctions. Septic shock is the sepsis-induced hypotension, which is unresponsive to adequate fluid resuscitation, associated with abnormalities (Bone et al. 1992; Markiewski 2008). As soon as the infection occurs, it deteriorates the neonatal health, and the neonate develops septic shock even before the identification of the cause (Segura-Cervantes 2016).
Answers
Andrew Schofield, Paul Schofield in The Complete SAQ Study Guide, 2019
Meningitis is inflammation of the meninges of the brain. It is often viral in origin, but due to the significant morbidity and mortality associated with bacterial meningitis, all cases should be treated as bacterial until proven otherwise. Infants, young children and the elderly are the most susceptible age groups. Patients present with fever, headache, photophobia, neck stiffness or altered mental consciousness, but in the high-risk age groups mentioned above, patients may present with non-specific symptoms and signs, so a high index of suspicion is required. It is important to understand that a petechial rash is seen in meningococcal septicaemia and is not in itself a sign of meningitis. Lumbar puncture is essential, but CT head scans should be performed if there are concerns regarding raised intracranial pressure. Early antibiotic therapy is important to reduce the morbidity and mortality, and empirical antibiotics should be commenced prior to knowing culture results. Supportive therapy such as analgesia antipyretics and hydration is also required. It is important to remember that meningitis is a notifiable disease.
Cerebrospinal fluid leaks secondary to dural tears: a review of etiology, clinical evaluation, and management
Published in International Journal of Neuroscience, 2021
Jason Gandhi, Andrew DiMatteo, Gunjan Joshi, Noel L. Smith, Sardar Ali Khan
The meninges are composed of three membrane structures that encapsulate the brain and spinal cord. The three membranes of the meninges from most superficial to deep are respectively the: dura, arachnoid, and pia mater. The dura mater is also referred to as the pachymeninx or “thick meninx”, while the pia and arachnoid mater collectively are referred to as the leptomeninx or “thin meninx” [5]. The dura itself is composed of three layers: the most superficial layer called the endosteal (i.e. periosteal), the meningeal layer, and the deepest layer called the dural border cell layer [6,7]. The dural border cell layer interacts with the arachnoid barrier cell layer and basement membrane of the arachnoid mater. It is in the arachnoid reticular layer and subarachnoid space that the CSF is contained. The depth of the subarachnoid space is variable depending on the relationship between the arachnoid and pia mater [7].
Management of complex tuberculosis cases: a focus on drug-resistant tuberculous meningitis
Published in Expert Review of Anti-infective Therapy, 2018
Ravindra Kumar Garg, Imran Rizvi, Hardeep Singh Malhotra, Ravi Uniyal, Neeraj Kumar
Classically, pathogenesis of tuberculous meningitis is considered to be a two-stage process. M. tuberculosis is transmitted via airborne droplet nuclei mechanism. A tubercular focus then develops in the lung, which subsequently releases the bacteria into the bloodstream. It reaches the brain via the hematogenous route, where it is deposited as small granulomas in the meninges and subpial brain parenchyma (Rich focus). Tuberculous meningitis develops when a caseating Rich focus releases caseous material containing M. tuberculosis into the subarachnoid space [36]. Donald and co-workers, alternatively, suggested that meningeal or subcortical tuberculous focus, in children with miliary tuberculosis, develops during the process of miliary dissemination. These tuberculous foci soon after its development may caseate and discharge its contents into the subarachnoid space causing meningitis [37].
Tailoring synthetic polymeric biomaterials towards nerve tissue engineering: a review
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Hamed Amani, Hanif Kazerooni, Hossein Hassanpoor, Abolfazl Akbarzadeh, Hamidreza Pazoki-Toroudi
Owing to intricate tasks and even supporting the most daily living functions, the CNS possesses a high degree of anatomical complexity [26]. The PNS is formed from peripheral, cranial (arising from the brain) and spinal nerves as well as their motor and sensory endings. A multilayered building containing bone, meninges, connective tissue and skin support the nervous system. In fact, the spinal cord acts as a bridge for connecting the brain to the rest of the body and facilitates receiving and sending sensory and motor information via electrochemical impulses to and from the PNS [27]. There are two types of cells within the nerve system including neurons and neuroglia. Neurons are known as the basic structural and functional components of the nervous system and are comprised of soma, axons, and dendrites. Dendrites provide the possibility for transmission of electrical signals to soma and axons steer impulses away. Glial cells, or neuroglia act as supporting cells for neuronal function and are classified into three type cells including astrocytes, oligodendrocytes (present in the CNS) and Schwann cells (present in the PNS). The amount of glial cells is more than neurons in the nervous system. Although neurons are not capable to perform mitosis, glial cells have the ability in cell division. It is also worth to note that neurons can rehabilitate or trigger sprouting in certain conditions. The spinal cord is comprised of dendrites, axons, and cell bodies.