China
Africa
Explore chapters and articles related to this topic
The nervous system and the eye
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
James A.R. Nicoll, William Stewart, Fiona Roberts
Central chromatolysis occurs between 5 and 8 days after transection, and is characterized by swelling of the cell body and displacement of the nucleus to the periphery of the cell. The cytoplasm becomes pale and homogeneous and there is dispersion of the Nissl substance – chromatolysis – accompanied by increased synthesis of RNA and protein. This reaction occurs in central and peripheral neurons, but particularly the latter. It may be followed by recovery with or without axonal regeneration, or may proceed to degeneration and ultimate death of the neuron. Effective regeneration is limited to the peripheral nervous system (PNS). In contrast, those neurons with projections lying entirely within the CNS tend to undergo retrograde degeneration and die. However, there is evidence of continuing neurogenesis from a population of stem cells residing in the subventricular zone of the basal ganglia and hippocampi.
Association between subarachnoid hemorrhage-induced hydrocephalus and hydromyelia: pathophysiological changes developed in an experimental model
Published in Neurological Research, 2023
A ‘craniospinal pressure dissociation’ theory was postulated by Williams [6]. This theory posited that significant pressure changes during daily activities may increase the intrathoracic pressure, as reflected in the spinal CSF through the epidural spinal veins [6]. The CSF flow from the cranial to the SAS reflects expansile brain motion during the cardiac cycle, especially in the arterial pulse. A syrinx cavity is frequently accompanied by a myelomalacia area. The progression of a syrinx cavity transmits the pressure to the medulla spinalis surface. The syrinx does not require communication between the central channel and the ventricular system. The dorsal root entry zone and the perivascular spaces can influence the communication between the central channel and extracellular spaces of the medulla spinalis. This mechanism can play a primary role in compensating for the changes occurring in the perimedullary CSF flow. However, pathologies and iatrogenic conditions, such as spinal meningitis, SAH, peridural anesthesia, intramedullary spinal surgery, infarction, trauma, and spinal injuries, frequently cause arachnoid scarring that impaired this mechanism [24,25]. Both parenchymal (extracanalicular) syringes and paracentral dissections of central channel syringes are lined with glial or fibroglial tissues that are frequently ruptured into the SAS. The fibroglial tissue is characterized by Wallerian degeneration, neuronophagia, and central chromatolysis. The clinical presentation in patients varies depending on the affected tracts and nuclei with this cavity [2,24,25].
Systemic angiopathy and axonopathy in hereditary transthyretin amyloidosis with Ala97Gly (p. Ala117Gly) mutation: a post-mortem analysis
Published in Amyloid, 2018
Haruki Koike, Takeshi Yasuda, Ryoji Nishi, Shohei Ikeda, Yuichi Kawagashira, Masahiro Iijima, Gen Sobue, Masahisa Katsuno
In the spinal cord, parenchyma was intact in terms of amyloid deposition at any levels. Although amyloid deposition was found in the leptomeningeal small vessels, it was mild compared to other visceral organs. Central chromatolysis was observed in spinal motor neurons; however, the numbers of neurons in the anterior horns and Clarke’s columns were well preserved. In the ventral and dorsal spinal roots, amyloid deposition was not apparent and myelinated fibres were preserved. Massive amyloid deposits were seen around the dorsal root ganglia and thoracic sympathetic ganglia but minimal deposits in the parenchyma of these ganglia. The extent of neuronal loss was also minimal in these ganglia (Figure 1(F)). Myelinated fibres were depleted even in the proximal portions of the sciatic/tibial and median nerves (Figure 1(G)). Perineural amyloid deposition was prominent throughout the length of these nerves, whereas it was mild to moderate in the endoneurium (Figure 1(H)).
Brain targeted delivery of mucoadhesive thermosensitive nasal gel of selegiline hydrochloride for treatment of Parkinson's disease
Published in Journal of Drug Targeting, 2018
Vinay Sridhar, Sarika Wairkar, Ram Gaud, Amrita Bajaj, Pramod Meshram
Vacuolation is a cellular response triggered in order to immobilise pathological prion proteins, like α-synuclein associated commonly with PD, having the ability to form channels that compromise cellular membranes [57,58]. Fluid accumulation in the neurophil creating a vacuolated space has been reported to be observed in the initial stages of neurodegeneration (Figure 8(A)). Also, shrunken nuclei can be seen often due to excessive fluid accumulation within the neuron making the nucleus appear shrunken (Figure 8(B)). Furthermore, central chromatolysis was observed in Figure 8(C) in which the nucleus lost its central position becoming eccentric, lying adjacent to the cell membrane due to the neural insult and loss of nuclear suspension. During recovery from the neural insult, the Nissl substance may reaggregate, but from the centre, so that there remains cytoplasmic clarity peripherally leading to peripheral chromatolysis, considered a microscopic indication of early neuronal recovery. Due consideration was given to processing artefacts and such observations were excluded as neuronal damage. The ‘dark neuron’ artefact as reported previously was observed in some slides (Figure 8(D)) [59]. It is a consequence of contraction in perturbed neurons due to mechanically induced polarisation, glucose deprivation, and disruption of neuronal membranous attachments, leading to shrinkage during dehydration for paraffin embedding, and reduced cytoplasmic osmolarity.