SECTION VII. Neuroskeletal System
A Anterior Cervical Diskectomy/Fusion
1. Introduction
Anterior cervical diskectomy or fusion is most commonly performed for symptomatic nerve root or cord compression. Compression may occur from protrusion of an intervertebral disk or osteophytic bone into the spinal canal. An intervertebral disk usually herniates at the fifth or sixth cervical levels. A bone graft may be taken from the iliac crest, or backbone may be used.
2. Preoperative assessment and patient preparation
a) Airway assessment should include thorough assessment of the range of motion of the neck. Neurologic deficits with limited neck movement may require intubation with the head in a neutral position. Intubation can be performed using passive immobilization or in-line traction. Awake intubation with proper positioning is the safest option.
b) Neurologic deficits should be documented. Patients typically complain of neck pain radiating down one arm, which can progress to weakness and atrophy.
c) Diagnostic tests include type and screen, complete blood count, and other tests as the patient’s condition indicates.
d) Preoperative medication and intravenous therapy: Patients may have considerable pain preoperatively and require a narcotic with premedication. If a difficult airway is anticipated, premedication should be used sparingly. Use a 16- or 18-gauge intravenous catheter with minimal fluid replacement.
3. Room preparation
a) A standard tabletop setup is used.
b) The patient is in the supine position, with arms tucked at the side; a small roll may be placed under the shoulders. Pad elbows to avoid ulnar compression, and use slight knee flexion because many patients also have lumbar disease. A doughnut or foam headrest may be used.
c) Use a single, 18-gauge nonpositional intravenous catheter (arms tucked) with minimal fluid replacement.
4. Perioperative management and anesthetic technique
a) Induction
(1) General anesthesia with endotracheal intubation is used.
(2) Tape the endotracheal tube to the side opposite of where the surgeon stands. Keep tape out of the sterile field.
b) Maintenance
(1) The trachea and esophagus are retracted laterally while the common carotid is retracted medially. The temporal artery can be palpated to monitor for carotid artery occlusion. There is the potential risk of damage to the recurrent laryngeal nerve, major arteries, veins, or esophageal perforation.
(2) Blood loss is usually not significant, but epidural venous oozing can occur.
(3) Patients with spinal cord compression have an increased risk for decreased spinal cord perfusion and may not tolerate intraoperative hypotension.
(4) Spinal cord monitoring with somatosensory-evoked potentials may be performed.
(5) The absence of muscle relaxation is required for intraoperative nerve function testing.
(6) If a nerve stimulator is used on the face, limit twitch application to when the surgeon is not operating, because the face may move during stimulation.
c) Emergence
(1) Most patients are extubated in the operating room after the procedure.
(2) Coughing and bucking on the endotracheal tube should be avoided because they can dislodge the bone plug. Intravenous lidocaine can be administered before extubation. The neck must remain in a neutral position. A neck brace may be applied.
(3) Extubate before application of the neck brace; a jaw lift may be required. The patient should be awake before leaving the operating room to allow the surgeon to assess neurologic function.
(4) Consider leaving the patient intubated if there is large blood loss or fluid replacement, difficult intubation, multilevel surgery, or difficult tracheal retraction that can lead to tracheal or airway edema.
(5) Assess the patient’s voice for recurrent laryngeal nerve damage, which rarely causes airway obstruction and usually resolves in a few days to 6 weeks.
B Lumbar Laminectomy/Fusion
1. Introduction
Lumbar laminectomy is most commonly performed for symptomatic nerve root or spinal cord compression. Compression may occur from protrusion of an intervertebral disk or osteophyte bone into the spinal canal. An intervertebral disk usually herniates at the L4 to L5 or L5 to S1 intervertebral space. A laminectomy procedure involves the complete removal of lamina.
Lumbar fusion is performed when there is instability of the spine. Bone graft material can be obtained from the patient’s iliac crest or from backbone. Back injuries account for a large percentage of work-related injuries and are a leading cause of work absences. Estimates are that 80% of the population will experience some type of back problem.
2. Preoperative assessment and patient preparation
a) History and physical examination: Assess and document neurologic deficits of the lower extremities.
b) Diagnostic tests: Type and screen blood, and obtain a complete blood count.
c) Preoperative medication and intravenous therapy
(1) Consider a narcotic with premedication if the patient experiences pain.
(2) Consider an antisialagogue because most spinal surgery is performed with the patient in the prone position.
(3) Use a 16- or 18-gauge intravenous catheter with minimal fluid replacement.
3. Room preparation
a) Monitoring equipment: Standard
b) Pharmacologic agents: Vasopressors, steroids, and antibiotics
c) Position
(1) Prone, lateral, and knee-chest positions are used.
(2) Have a foam headrest, doughnut, axillary roll, and indicated padding available.
(3) Specially designed frames may be used to aid in positioning.
4. Anesthetic technique
a) Local infiltration, regional blockade, and general anesthesia are used.
b) Regional blockade: This reduces blood loss and shrinks epidural veins; analgesia to T7 to T8 is required; and regional anesthesia cannot be used if nerve function will be tested.
c) Epidural: This must be in a single dose with the catheter removed.
d) Spinal: Hypotension may be accentuated with position change.
5. Perioperative management
a) Induction
(1) If the prone or knee-chest position is used, anesthesia is induced while the patient is on the stretcher.
(2) Position changes may be done in stages to avoid hemodynamic compromise. It may be necessary to lighten the anesthetic and increase fluids before the position change. A vasopressor may be needed to treat hypotension.
(3) Tape the endotracheal tube to the side of the mouth that will be positioned upward. Confirm endotracheal tube placement after positioning.
b) Maintenance
(1) Question the surgeon regarding the use of muscle relaxants. If nerve function is to be tested, a single dose of an intermediate nondepolarizing muscle relaxant may be used for intubation.
(2) Pad all pressure points and check for pressure on the face every 15 minutes during surgery.
(3) Blood loss is rarely sufficient to necessitate deliberate hypotension. The wound may be infiltrated with an epinephrine solution to decrease intraoperative blood loss.
(4) Sudden profound hypotension may indicate major intraabdominal vessel (iliac, aorta) damage with bleeding occurring in the retroperitoneal cavity, which may not be visible to the surgeon.
(5) Infiltration of the wound with a local anesthetic will decrease postoperative pain.
c) Emergence
Extubation is performed when the patient is supine. The patient may need to be awake at the end of the procedure to allow the surgeon to assess for neurologic deficits.
6. Postoperative considerations
The patient can usually be transported in any position because stability of the back is rarely compromised.
C Spinal Cord Injuries
1. Introduction
Spinal cord transection is the description of spinal cord injury that is manifested as paralysis of the lower extremities (paraplegia) or of all extremities (quadriplegia). Spinal cord transection above the level of C2 to C4 is incompatible with survival, because innervation to the diaphragm is likely to be destroyed.
The most common cause of spinal cord transection is the trauma associated with a motor vehicle or diving accident that results in fracture dislocation of cervical vertebrae. Occasionally, rheumatoid arthritis of the spine leads to spontaneous dislocation of the C1 vertebra on the C2 vertebra, producing progressive quadriparesis. These patients can suddenly become quadriplegic. The most frequent nontraumatic cause of spinal cord transection is multiple sclerosis. In addition, infections or vascular and developmental disorders may be responsible for permanent damage to the spinal cord.
2. Preoperative assessment
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