Spinal cord damage
- Spinal cord damage is very rare.
- Mechanism
- Inadequate blood supply to the spinal cord This is the main cause of spinal cord damage associated with a general anaesthetic.
- The following factors may cause oxygen starvation of the spinal cord:
- Low blood pressure
- Stroke
- Compression or stretch of blood vessels, making them narrower. The ‘anterior spinal artery syndrome’ is caused by reduced blood flow in this artery. Part of the spinal cord becomes starved of oxygen and may be damaged. This can result in permanent lower limb paralysis. If you have disease of your blood vessels elsewhere (for example coronary heart disease) the risk of this happening is slightly higher, but the risk remains very rare.
- Your anaesthetist will adjust your anaesthetic to keep your blood pressure at a level that he/she considers safe.
Likelihood of peripheral nerve and spinal cord damage:
- The exact risk of nerve damage is not known.
- Peripheral nerve injury
- Minor symptoms occur frequently, perhaps as high as 1 in 100 people having a general anaesthetic. The vast majority of these recover completely.
- In one very large study, the overall risk was about 1 in 2,700 patients having a general anaesthetic.
- In other smaller studies, the risk of a significant peripheral nerve injury lasting more than one year, was between 1 in 1,000 and 1 in 1,500 patients.
- Between 57% and 93% recovered completely by one year.
- Spinal cord damage
- Solely as a result of general anaesthesia alone in patients having routine surgery is very rare.
- There are no accurate figures for this.
Perioperative Peripheral Nerve Injury (PPNI):
- Risk of peripheral nerve damage:
- Patient factors
- Medical conditions – diabetes, smoking, high blood pressure, vascular disease.
- Being male.
- Increasing age.
- Being very overweight or extremely thin.
- Surgical factors
- More complicated operations which involve more instruments are more likely to damage nerves than simpler operations.
- Certain operations, including:
- Operations on the spine or brain
- Cardiac or vascular operations (on the heart or major blood vessels)
- Operations on the neck or parotid (a gland in the face)
- Some kinds of breast operation
- Operations in which a tourniquet (a tight band around a limb) is used to reduce bleeding.
- Positioning
- Prone
- Lateral
- Typically presents as
- Neuropraxia or
- Axonotmesis.
- Lower Extremity Injuries:
- Patients with significant fixed sagittal malalignment can sustain various lower extremity nerve compressions, such
- As quadriceps palsy, even with appropriate padding, which can be relieved by appropriate recognition and interventions.
- Upper Extremity Injuries:
- Brachial Plexus
- Highly susceptible to stretch injuries due to its fixation at the cervical and axillary fascia and its traversal through bony architecture (clavicle, first rib, humeral head).
- Risk factor
- Abduction of the arm greater than 90° (Greatest risk)
- Extension, external rotation plus abduction of the arm
- Rotation plus lateral flexion of the neck in the ipsilateral direction
- Application of shoulder braces.
- The most common clinical presentation is a motor deficit, with the majority of cases resolving over time.
- Specific Peripheral Neuropathies:
- Ulnar nerve palsy
- Increased risk with
- Elbow flexion greater than 90°
- Most vulnerable peripheral nerve in the upper extremity to brachial artery ischemia.
- Direct pressure to the cubital tunnel
- Obesity and preoperative cubital tunnel syndrome are identified risk factors for ulnar nerve injury.
- Malpositioning of a blood pressure cuff
- Lateral femoral cutaneous neuropathy (meralgia paresthetica)
- Reported in up to 24% of patients undergoing prone spinal surgery.
- This is believed to be caused by direct compression of the nerve by the pelvic bolsters near the anterior superior iliac spine.
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