![reflex after effects reflex after effects](https://i.ytimg.com/vi/0dGr8S-NXMk/maxresdefault.jpg)
Cervical lesions cause total loss of sympathetic innervation and lead to vasovagal hypotension and bradyarrhythmias – which resolve in 3–6 weeks. Sacral parasympathetic loss may be encountered in lesions below T6 or T7. Parasympathetic is preserved but the synergy between sympathetic and parasympathetic system is lost in cervical and high thoracic SCI lesions. In spinal cord injuries above T6, neurogenic shock may occur, from the loss of autonomic innervation from the brain. Phase 4 on the other hand, is soma-mediated, and will take longer for the soma to transport various growth factors, including proteins, to the end of the axon. The first synapses to form are from shorter axons, usually from interneurons – this categorizes Phase 3. Interneurons and lower motor neurons below the SCI begin sprouting, attempting to re-establish synapses. Phases 3 and 4 are characterized by hyperreflexia, or abnormally strong reflexes usually produced with minimal stimulation. The reason reflexes return is the hypersensitivity of reflex muscles following denervation – more receptors for neurotransmitters are expressed and are therefore easier to stimulate. Restoration of reflexes is not rostral to caudal as previously (and commonly) believed, but instead proceeds from polysynaptic to monosynaptic. Monosynaptic reflexes, such as the deep tendon reflexes, are not restored until Phase 3.
![reflex after effects reflex after effects](https://www.softpedia.com/screenshots/Adobe-After-Effects_3.png)
The first reflexes to reappear are polysynaptic in nature, such as the bulbocavernosus reflex. Phase 2 occurs over the next two days, and is characterized by the return of some, but not all, reflexes below the SCI. After an SCI, these cells lose this input, and the neurons involved become hyperpolarized and therefore less responsive to stimuli. The neurons involved in various reflex arcs normally receive a basal level of excitatory stimulation from the brain. Phase 1 is characterized by a complete loss-or weakening-of all reflexes below the SCI.
![reflex after effects reflex after effects](https://www.repaire.net/forums/data/resource_icons/1/1219.jpg)
proposed a four-phase model for spinal shock in 2004 as follows: