Comparison of the chronic cellular, molecular, and clinical pathophysiological changes after single and repetitive TBI
| Pathophysiological chronic changes Both single and repetitive brain trauma lead to development of long-term neurological disorders [33, 35, 36, 39, 80, 81], depending on the extent of the acute injury |
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| Single TBI (sTBI) | ||
| Cellular | Molecular | Clinical |
| Glial scaring [91] Hyperactivated microglia [77, 125, 126] |
Accumulation of β-amyloid plaques [142-145], mostly in grey and less in white brain matter [142], predominantly with fibrillar characteristics (such as seen in developed Alzheimer's disease) [137, 146] and possible genetic predisposition risk [142, 147] Neurofibrillary tangles (NFT) with a distribution that matches the one in Alzheimer's disease [141, 148] Accumulation of α-synuclein in some patients [149, 150] Loss of synapses and progressive neuronal deficit [142, 151] TDP-43 proteinopathy? [56, 152, 153] |
Generalized brain atrophy [137, 154, 155] includes entire brain parenchyma (including the frontal), grey and white matter of the cerebrum, cerebellum, and brainstem [155] with volume reduction of corpus callosum [58, 156] Cognitive disorders [157] depending on the degree of degenerated anatomical structures [158] Increased Alzheimer’s disease risk [136, 159, 160] |
| Repetitive TBI (rTBI) | ||
| Cellular | Molecular | Clinical |
| Tau deposits in astrocytes and neurons [161, 162] Hyperactivated microglia [77] |
Hyperphosphorylated tau protein aggregates (NFTs) in the cortical sulci, perivascular regions of the frontal lobe, midbrain, thalamus, basal ganglia, amygdala and hippocampus [137, 163] Beta-amyloid aggregates and Lewi’s bodies present in some patients [137, 164] TDP-43 proteinopathy [152, 154, 164-166] |
Localized brain atrophy detected in the frontal and temporal part of the cortex and the cerebellum [137, 167]; atrophy of the hippocampus and amygdala and entorhinal cortex [40, 138, 168, 169] Enlargement of the cavum septum pellucidum [40, 170, 171], with occasional absence of the septum or its separation from the fornix and the corpus callosum [40, 137, 171-176] Cognitive dysfunction [168, 169, 177] with pyramidal, extrapyramidal, and cerebellar dysfunction observed [137] Increased CTE risk development [164] |