Pathology | Points assigned |
---|---|
Myelin1-b | 1 |
Axoplasm1-c | 2 |
Periaxonal Space1-d | |
25–49% | 4 |
50–74% | 6 |
≥75% | 10 |
Necrotic Axoplasm1-e | 10 |
F1-a The AII for an axon is the sum of points assigned for myelin and axoplasmic pathology and for periaxonal space, as described previously in detail.
↵F1-b Myelin pathology was defined as unwinding of the myelin lamellae that can be either slight or severe unraveling, appearing as whorls of membranous matter, abnormal spaces in between the lamellae, hypermyelination or hypomyelination, and fragmentation of the myelin sheath. One point was assigned to any axon displaying one or more of these pathologies in addition to points assigned for the other categories of pathology.
↵F1-c Axoplasmic pathology was defined as mitochondria swelling, presence of vacuoles/vesiculation, and condensation or loss of neurofilaments and microtubules. Axons with one or more of these pathologies were assigned 2 points, in addition to points assigned for the other categories of pathology.
↵F1-d Periaxonal spaces were defined as spaces between the axolemma and inner lamella of the myelin sheath. These spaces were occasionally seen in axons in uninjured tissue but never constituted >25% of the intramyelin area. Therefore, only spaces >25% of the intramyelin area were scored with assigned points increased to reflect greater degrees of spacing.
↵F1-e Axons devoid of cytoskeletal structures in which the axoplasm was comprised of a flocculent substance were classified as having “necrotic” axoplasm and given the maximum score of 10.