Spinal cord swelling

Afferent neurons that transmit sensory information toward the spinal cord are referred to as first-order sensory neurons. The cell bodies of these neurons are found in the dorsal root ganglia. These ganglia form a swelling in each of the dorsal roots just outside the spinal cord. The portion of the axon between the distal receptor and the cell body is referred to as the peripheral axon and the portion of the axon between the cell body and the axon terminal within the CNS is referred to as the central axon. 

However, the pathway of pain signals arising from tissue and then traveling to the spinal cord and brain is not a one-way street. It turns out that nerve endings in the skin or tissue can also release peptides such as substance P, which can alter the activity of immune cells or cause blood vessels to dilate. This causes swelling or further alters the pain response. Thus, not only does damaged tissue communicate with the central nervous system, but the central nervous system also sends chemical feedback to the site of injury or tissue damage. 

In a few rare instances, lumbar puncture cannot be performed, because the amount of swelling within the skull is so great that the intracranial pressure (pressure within the skull) is extremely high. This pressure is always measured immediately upon insertion of the LP needle. If it is found to be very high, no fluid is withdrawn, because withdrawal of fluid could cause herniation of the brain stem. Herniation of the brain stem occurs when the part of the brain connecting to the spinal cord is thrust through the opening at the base of the skull into the spinal canal. Such herniation will cause com-... 

HIV leukoencephalopathy is characterized by diffuse damage to the white matter with loss of myelin, reactive astrogliosis, multinucleated cells, and macrophages. IHC or ISH helps confirm the association of HIV with the process. Leukoencephalopathy occasionally manifests as marked vacuolar myelin swelling. This finding is more common in the spinal cord, however, where it forms multiple foci of vacuolar myelopathy that resemble combined systems degeneration without pernicious anemia. 

Sufficiently high exposures to alkylbenzenes—such as //-diethylbenzene, -triethylbenzene, -trimethylbenzene, and isopropylbenzene—can produce adverse motor and sensory effects in rats after inhalation. Gagnaire et al. (1990) reported decreased motor and sensory conduction velocities and decreased amplitude of the sensory action potential of the tail nerve in rats exposed repeatedly to a mixture of diethylbenzene and its major metabolite, 1,2-diacetylbenzene (DAB). In the rat, 1,2-diethylbenzene was about 5 times more potent a neurotoxicant than -hexane (Gagnaire et al. 1990). Spinal-cord axonal swelling with partial demyelination has been associated with DAB exposure in rats (Kim et al. 2001). The neurotoxicity of 1,2-diethylbenzene appears to be related to formation of protein complexes reaction with amino acids of proteins to form pyrolated polymers that lead to protein cross links. 

Figure 3. Microphotographs of cervical spinal cord (a), cross (b) and longitudinal (c) sections of lateral metatarsal nerve from IFP (1), antidote-treated (2) and TOCP-treated (3) hens. Note axonal swellings, necrosis and myelin degeneration in TOCP and IFP samples. Tissues embedded in epoxy, stained with toluidine blue. 160X. (Reproduced with permission from Ref. 4. Copyright 1984 Springer-Verlag, New York, Inc.)...

Lesions are minimal, although mild cerdxal edema (brain swelling) may be present Sjpongy degeneration occurs in the white matter of tite brain, spinal cord, and optic rterve. 

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