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Patients with preexisting neurologic disease present a unique challenge
to the anesthesiologist. Knowledge of the pathophysiology of the disease and
the effect of anesthetic drug therapy on the disease process is essential
for the safe management of anesthesia for these patients. Both active and
dormant neurologic diseases may worsen in the perioperative period,
independent of the chosen anesthetic method. However when regional
techniques are used, the cause of postoperative neurologic deficits may be
difficult to evaluate as neural injury can be related to a wide variety of
reasons, ie, surgical trauma, tourniquet pressure, improper positioning, or
anesthetic technique.1 The possibility of needle-induced
trauma, local anesthetic toxicity, or neural tissue ischemia or damage
during regional anesthesia has led many anesthesiologists to avoid
regional techniques in patients with underlying neurologic diseases.
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Many of these patients can benefit from regional
techniques. Greater autonomic stability, the ability to provide selective
anesthesia and analgesia, greater hemodynamic stability (especially with
peripheral nerve block anesthesia in patients with concurrent
cardiomyopathy), and the avoidance of side effects related to general
anesthetics and opioids are a few of the advantages.2,3
Careful preoperative neurologic evaluation, evaluation of the risk/benefit
ratio, and a comprehensive discussion with the patient about the anesthetic
plan and the possibility of worsening neurologic signs and symptoms
unrelated to the anesthetic technique is important for successful
implementation of regional techniques in this patient population.
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Although perioperative nerve injuries have been well recognized as a
complication of spinal and epidural anesthesia, severe or disabling
neurologic complications occur relatively rarely. In 1999, Cheney and
colleagues examined the American Society of Anesthesiologists Closed Claims
database to determine what percentage of the claims were related to nerve
damage in malpractice cases.4 Of the 4183 claims reviewed,
670 (16%) were anesthesia-related nerve injuries. Ulnar neuropathies were
the most frequently reported, followed by other injuries to the brachial
plexus, lumbosacral nerve roots, and spinal cord. The injuries were
bilateral in 14% of the ulnar injuries and in 12% of the brachial
plexus injuries. The important factor in this analysis is that the incidence
of ulnar and brachial plexus injuries was greater with general anesthesia
than with regional anesthesia.5,6 Horlocker and coworkers
examined the cause of perioperative nerve injury in a review of 607 patients
undergoing 1614 axillary blocks for upper extremity surgery. Various surgical variables
(direct trauma, stretch, hematoma, vascular compromise, case or tourniquet
ischemia) were thought to be the cause of neurologic complications in the
majority of the cases (89%).7
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In the Closed Claims Analysis 189 (4%) involved either the
lumbosacral root or the spinal cord. Injuries to these areas were more
frequently associated with regional anesthesia. The lumbosacral root
injuries were thought to be related to paresthesias during needle or
catheter placement or pain on injection of local anesthetic. The spinal cord
injuries were related to blocks for chronic pain or neuraxial blocks on
patients receiving systemic anticoagulation. These injuries ...