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Optic Nerve Disorders - part 6

Mất quy định của homeostasis canxi dẫn đến thay đổi của canxi ngoại bào không gian nội bào điện áp-gated và gated kênh canxi thụ. Canxi trong tế bào dư thừa dẫn đến tế bào death.63 Ngoài ra thiếu máu cục bộ, viêm góp phần gây thiệt hại hơn nữa thần kinh | 138 J.W. Chan syndrome causing more ischemia to the optic nerve. Loss of regulation of calcium homeostasis leads to shifting of extracellular calcium to the intracellular space by voltage-gated and receptor-gated calcium channels. The excess intracellular calcium leads to cell death.63 Besides ischemia inflammation contributes to further neural damage. Mediators of inflammation are released to attract polymorphonuclear lymphocytes and macrophages. Within the first 2 days after injury polymorphonuclear lymphocytes predominate to cause immediate tissue damage. They are then replaced by macrophages by about 7 days after injury. These macrophages are thought to contribute to delayed tissue damage as in delayed posttrau-matic demyelination. Macrophages release glial promoting factors. This astroglial response after spinal cord injury may inhibit axonal regeneration processes. Inhibition of macrophage responses have been shown to decrease reactive gliosis as shown in spinal cord injury studies.62 63 Management Currently the use of systemic corticosteroids in traumatic optic neuropathy is accepted as some form of treatment that is better than none at all. The beneficial effects of this medication are extrapolated from those shown in the treatment of acute spinal cord injury in the second National Acute Spinal Cord Injury Study NASCIS-2 .64 In NASCIS 2 64 a multicenter randomized double-blind placebo-controlled study in patients with acute spinal cord injury patients were randomly assigned to receive placebo naloxone or methylprednisolone within 12h of spinal injury. Methylprednisolone was given as an initial dose of 30 mg kg followed by a continuous infusion of 5.4 mg kg h. Compared with placebo treatment with methylprednisolone within 8h of injury resulted in a significant improvement in motor and sensory function. These effects of methylprednisolone in the treatment of spinal cord trauma do not seem to extend to the treatment of optic nerve trauma however. The .