Week 3 - Spine Surgery Anesthesia Flashcards
(47 cards)
Describe the anatomy of the spinal cord
Extends from medulla (at foramen magnum) to the Filum Terminale (thread like structure made up of connective tissue) –> attaches to coccyx
31 Pairs of spinal nerves that carry motor and sensory information
-lumbar and sacral nerves have long roots that make up the Cauda Equina
Divided into dorsal, lateral, and ventral regions
H shaped central gray region – unmyelinated fibers
What spinal cord nuclei are in the dorsal horn? (5)
- Marginal zone (Rexed’s Laminae I)
- Substantia Gelatinosa (Rexed’s Laminae II)
- Nucleus Proprius (Rexed’s Laminae III, IV)
- Neck of Dorsal Horn (Rexed’s Laminae V)
- Base of Dorsal Horn (Rexed’s Laminae VI)
What spinal cord nuclei are in the intermediate zone? (1)
Clark’s Nucleus, Intermediate Nucleus
Rexed’s Laminae VII
What spinal cord nuclei are in the ventral horn? (2)
Commissural Nucleus (Rexed’s Laminae VIII)
Motor Nuclei (Rexed’s Laminae IX)
What spinal cord nuclei are in the gray matter surrounding the central canal?
Grisea Centralis (Rexed’s Laminae X)
Describe the Pain and Temperature Pathways
Pain and temp fibers from the brain synapse in trigeminal ganglion:
- enter the pons and form trigeminal nerve (CN V)
- these fibers subsequently synapse with second order neurons in the nucleus of the descending tract of CN V
- pain and temp receptors in the skin of the trunk and extremities send signals to spinal cord via dorsal roots of spinal nerves
*pressure and touch also synapse with CN V
Where do the fibers for proprioception of the muscles of the face (facial expressions) and mastication synapse?
They synapse in cell bodies located in midbrain (mesencephalic nucleus)
Where do fibers from the trunk and extremities that carry proprioception, vibration, and touch info synapse?
They synapse with neuron cell bodies in dorsal root ganglion
-first order axons then enter dorsal white column and ascend to medulla
What sensations does the Dorsal Column-Medial Lemniscal System sensory pathway transmit?
- Touch sensations requiring high degree of localization of the stimulus
- Touch sensations requiring transmission of fine gradations of intensity
- Phasic sensations, such as vibratory sensations
- Sensations that signal movement against the skin
- Position sensations from the joints
- Pressure sensations related to fine degrees of judgment of pressure intensity
What sensations does the Anterolateral System sensory pathway transmit?
- Pain
- Thermal sensations, including both warm and cold
- Crude touch and pressure sensations capable only of crude localizing ability on the surface of the body
- Tickle and itch sensations
- Sexual sensations
What do efferent (motor) pathways from the brain transmit?
Information to voluntary muscles of body, smooth muscle and cardiac muscle and various glands
What is the Corticospinal tract?
Motor pathway that supplies voluntary muscles of trunk and extremities
*9 CN supply voluntary muscles of the head and neck
What transmits efferent signals to smooth muscle, cardiac muscle, and some glands (lacrimal, bronchial)?
Autonomic PREganglionic fibers
What two arteries supply blood to the spinal cord?
One Anterior Spinal Artery – supplies blood to lower 2/3 of spinal cord
Two Posterior Spinal Arteries – supplies remaining 1/3
- also branches of the vertebral artery and radicular arteries
- run the length of the spinal cord
What is the Artery of Adamkiewicz? Where does it enter?
Responsible for much of the blood supply to the lower 2/3 of the spinal cord
Enters the cord at approximately T7
What is the difference between direct injury and indirect injury to the spinal cord?
Direct = trauma
Indirect = disease to surrounding bones, tissues, or blood vessels
What are symptoms of a cervical spinal cord injury?
- Unilateral/bilateral extremity weakness/paralysis
- Loss of consciousness
- Complete quadraperisis and respiratory failure
- Potential difficult airway
*associated with head trauma
Describe the cervical spine anatomy
Divided into upper (C1-C2) and lower (C3-C7) segments – upper have less space than lower segments
C1 (Atlas) forms Atlanto-Occipital joint with C2 (Axis)
*injury to atlanto-occipital joint results in high mortality due to anoxia (8-19% of fatal cervical spine injury autopsies)
What are the risks of direct laryngoscopy in airway management of spinal cord injury?
Technically difficult with cervical collar in place
Potential strain and movement of unstable spine (even with collar on)
What airway techniques create the greatest movement of the C-spine?
Chin lift
Jaw thrust
*pre-intubation positioning
What are the advantages and disadvantages of awake fiberoptic intubation for an unstable C-Spine?
Advantages:
- maintain neck in midline position
- good alternative if difficult mask ventilation
- immediate ability to assess and document post intubation neurologic exam
Disadvantages:
- technically challenging
- increased time requirement/cooperative patient
- equipment availability
- trauma (blood/fluids in airway) may compromise visibility/ aspiration risk due to topical med administration
After the initial insult what are spinal cord injury patients at risk for?
Spinal Shock
- associated with lesions above T4
- aggressive fluid management
- hemodynamic monitoring (bradycardia and vasodilation)
- monitor temperature closely (Poikilothermic below level of spinal cord injury)
After acute injury cases of hyperkalemia and cardiac arrest in paraplegic pts following succinylcholine admin – increased extrajunctional receptors
What are some of the common spine surgeries?
- Spinal Fusion: most common surgery for back pain – fuse vertebrae together
- Laminectomy: removal of parts of the bone, bone spurs, or ligaments in the back – relieves pressure on spinal nerves and can ease pain or weakness (can make spine less stable - may lead to fusion down the line)
- Foraminotomy: bone cut away at the sides of the vertebrae to widen the space where nerves exit – relieves pressure on the nerves and ease pain (may make spine less stable)
- Diskectomy: removal of all or part of the disk
What is scoliosis?
Abnormal curving of the spine
Congenital (present at birth) or Neuromuscular (caused by nervous system problems that affect muscles)
Treatment depends on cause, extent, where the curve is and if you are still growing
