Spinal Cord Flashcards
The spinal cord is perfused by
-2 posterior arteries (poster 1/3)
-1 anterior artery (anterior 2/3)
-6-8 radicular arteries
What is the most important radicular artery?
Artery of Adamkiewicz (T11 - T12)
Arises on the left side
Describe the organization of the 3 neuron pathway common to the spinal tracts
-First order neuron travels from the periphery to the s/c or brainstem
-Second-order neuron travels from the spinal cord or brainstem to a subcortical structure
-Third order neuron links the subcortical structure to the cerebral cortex
DCML (transmits? fibers?)
Dorsal column - Medial Lemniscal System
-transmits mechanoreceptive sensations: fine touch, proprioception, vibration, and pressure
-capable of two-point discrimination
-large, myelinated, rapidly conducting fibers
-more ‘evolved’ than ASST
Anterolateral System - Spinothalamic Tract
-transmits: pain, temperature, crude touch, tickle, itch, sexual sensation
-smaller, myelinated, slow fibers
What bedside exam can assess the integrity of the corticospinal tract?
-Babinski
-If (+), there is damage to the upper motor neurons
- + = toes flayed out
-Corticospinal (pyramidal) tract is the most important motor pathway!!
Upper vs lower motor neuron injury
Upper presents with hyperreflexia and spastic paralysis
Lower = impaired reflexes and flaccid paralysis
Pathophysiology of Neurogenic Shock
-T1 - T4 damage = unopposed vagal tone = bradycardia and decreased inotropy
-Decreased SNS tone = vasodilation, venous pooling
-The impaired sympathetic pathway from hypothalamus to blood vessels = inability to vasoconstrict = hypothermia
How can you differentiate neurogenic shock from hypovolemic shock?
-Neurogenic = bradycardia, hotn, hypothermia, pink warm extremities
-Hypovolemic = tachycardia, hotn, cool & clammy skin
Succ & SCI
-avoid 24 hours following injury
-wait for 6 mo - 1 yr to use agin
When does a patient w/SCI become at risk for AH?
-1 - 3 weeks after injury
-hollow organs (bladder,bowel,uterus)
-surgery - cysto or colonoscopy
-birth
-cutaneous sensation
-BM
85% of pt will have it if injury is above T6
Discuss pathophys of AH
HTN & BRADYCARDIA
-stimulation below level of SCI triggers a sympathetic reflex arc that creates a profound degree of v/c below level of injury
-baroreflex initiatied in carotid sinus
nasal stuffiness, HTN
How to treat AH
-remove stimulus
-deepen anesthetic
-anticholinergics
-sodium nitroprusside
avoid positive chronotropes
avoid succ for 6 mo after SCI
Discuss ALS
the progressive degeneration of motor neurons in the corticospinal tract. Astrocytic gliosis replaces the affected motor neurons. Both upper and lower motor neurons are affected.
UNKNOWN ETIOLOGY
Management of ALS anesthetic
Succ = lethal
Sensitive to NMBDs
Bulbar dysfunction - aspiration
Chest weakness
Consider postop mechanical ventilation
