Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.

Let’s discuss an elephant in the room of operating room anesthesia–the association between peripheral nerve blocks and nerve injury.


The use of peripheral nerve blocks has crescendoed in anesthesia practice, stimulated by the use of ultrasound-guided visualization of nerves. There are growing economic industries in ultrasound machines, ultrasound block needles, and in anesthesia personnel who bill for this additional optional procedure on orthopedic patients.

Ultrasound allows us to visualize the nerves, but there are no data demonstrating a lower neurologic complication rate with this ultrasound technique.(Liu SS, et al. A prospective, randomized controlled trial comparing ultrasound versus nerve stimulator guidance for interscalene block for ambulatory shoulder surgery for postoperative neurological symptoms. Anesth Analg. 2009;109:265-271).

The incidence of nerve injury following peripheral nerve block is low, but not zero. Per Gadsden, the mechanism of permanent nerve injury is felt to be either needle trauma, or toxicity of local anesthetics. In a review article by David Hardman MD MBA, of the University of North Carolina, the incidence of permanent injury rates, as defined by a neurologic abnormality present at or beyond 12 months after the procedure, ranges from 0.029% to 0.2%. This reviewed data came from old studies, dating from 2001 – 2012. There are no more recent published studies of large populations. Multiplying this 1/3000 to 1/500 incidence by the tens of thousands of nerve blocks performed yearly leads to a significant number of permanently damaged nerves.

This is a problem.

I would never agree to have an ultrasound-guided brachial plexus, femoral or popliteal nerve block performed on me.

Why not? Because I need my hands and upper extremities to function normally in order to earn a living as an anesthesiologist. Because I’m also active in a number of sports, and I need my legs and lower extremities to function normally in order to walk, run, and function in athletics.

For me, the acceptable incidence of permanent nerve injury to my limbs is zero. The incidence of permanent nerve injury with general anesthesia should be zero. Of course, if the surgical team is negligent and positions me in a dangerous posture during general anesthesia, there could be a compression or traction nerve injury, but this is exceedingly rare in competent hands. Of course, if an orthopedic surgeon is negligent and compresses, stretches or damages a nerve, there could be nerve injury, but again this is exceedingly rare in competent hands.

If I’m wary of having a peripheral nerve block performed on myself, then I must be wary for my patients as well. Every individual needs their upper and lower extremities to function normally to perform every day tasks, to perform their jobs, or to enjoy their leisure or athletic activities.

I contend that, as of 2018, the incidence and number of permanent nerve injuries during this era of ultrasound-guided nerve blocks looms larger than any medical literature confirms. Why is this? I believe there are several reasons for the under-reporting of nerve injury following peripheral nerve blocks:

  1. Time lag in published data. The data in the medical literature regarding peripheral nerve injury following nerve block is old. In a lecture on this topic by David Hardman MD MBA at the American Society of Anesthesiologists (ASA) national convention in San Francisco, none of the data regarding nerve injury complication was more recent that 2007. Recent data is still unreported, and remains to be analyzed.
  2. Time lag in Closed Claims data. The ASA Closed Claims data always lags behind the occurrence of complications. A typical malpractice lawsuit takes a long time (e.g. 4 – 7 years) to come to a conclusion. The ASA Closed Claim database may be 10 years or more in arrears before it is finally published.
  3. Some peripheral nerve injuries never get reported to anyone. Either the patient never informs the physician, the case never gets tallied in any database, the physician never informs any quality assurance (QA) committee, or the case meets its termination in a QA committee discussion that goes no further.
  4. No one publishes case reports of their complications. Do you think an anesthesiologist is motivated to publish a case report in which they had permanent nerve injury of the brachial plexus following an interscalene nerve block for shoulder surgery? Of course not. He or she wants that case buried deeply, with as few people as possible knowing. No one publishes their dirty laundry, hence the medical literature is lacking in adverse case reports.
  5. Academic professors specializing in regional anesthesia have little interest in publicizing data that could damn or minimize the importance of their chosen subspecialty. A physician who makes his or her living performing, teaching, and writing about a hammer has a conflict of interest when it comes to speaking out on the dangers of wielding that hammer.

In my role as a peer review physician, quality assurance committee member, expert legal witness, and simply as a physician in a busy medical system, I’m aware of more than a dozen patients who already have permanent nerve injury following an ultrasound-guided peripheral nerve block. None of their case histories has been published, and none of their cases have appeared in a published series of nerve injury complications.

Is there a cover-up ongoing regarding permanent nerve injury? There is certainly no publicizing of these complications.

Let me give you an example of another anesthesia technique that was associated with permanent nerve injury: In the 1990’s we routinely used hyperbaric 5% lidocaine for spinal anesthesia. Lidocaine had the advantage of supplying short (1 – 1 ½ hour) spinal anesthesia for simple cases such as cytoscopies, urethral surgeries, perineal surgeries, and inguinal hernias. Case reports of cauda equina syndrome emerged, in which some lidocaine spinal anesthetics were associated with inflammation of the distal spinal cord (cauda equina), which caused permanent lower extremity nerve injury. Because of this risk, the use of lidocaine spinal anesthesia disappeared. The risk of nerve injury was real, and the risk was too daunting to continue using that anesthesia technique.

Expect a similar story to evolve over the coming years regarding the current burgeoning practice of peripheral nerve blockade. “Complications of Peripheral Nerve Block,” an article published in the British Journal of Anaesthesia in 2010, stated that “complications of peripheral nerve blocks are fortunately rare, but can be devastating for both the patient and the anaesthesiologist.” Indeed, for the patients whose nerve injury does not resolve it can be a tragedy.

In his lecture on nerve injury complications of peripheral nerve block delivered at the 2018 ASA national convention in San Francisco, speaker David Hardman, MD MBA told a standing room only crowd of anesthesiologists that if your patient develops a permanent nerve injury following a peripheral nerve block, “you will be sued.” Why was there a huge crowd for this particular lecture? I believe it’s because many anesthesiologists are aware of the occurrence of nerve injury, and aren’t sure what to do about the incidence of ultrasound-guided nerve blocks in their practice.

No one wants to be sued, but per the Hippocratic Oath we must first do no harm. The real crisis is not that an anesthesia provider gets sued, but that the patient will go the rest of their lives without the normal use of their arm or leg.

General anesthesia has risks. Adding a regional anesthetic to a general anesthetic adds a second set of risks. At times regional anesthesia is indicated. I still perform peripheral nerve blocks on select patients, and I believe peripheral nerve blockade still has utility in anesthesia practice. I believe ultrasound-guided peripheral nerve blocks are indicated:

  1. If the scheduled procedure will cause significant post-operative pain, e.g. a total shoulder replacement.
  2. If parenteral narcotics are unlikely to relieve the pain satisfactorily, e.g. a total shoulder replacement, or you are doing a painful procedure on a patient who consumes chronic narcotics, and who will be tolerant to narcotic analgesia.
  3. If I explain the non-zero risk of permanent nerve injury, e.g. a risk of 1 in 3000 patients, and the patient both understands this risk and consents to proceed.

Seducing a patient into accepting a peripheral nerve block by minimizing the chance of permanent nerve injury with phases such as, “nerve injury is very, very rare,” or “nerve injury is very uncommon, and it usually resolves,” is deceptive medical practice. If that patient later develops permanent nerve injury, you can expect to be sued. A 2007 survey of academic regional anesthesiologists indicated that nearly 40% of respondents did not disclose the risks of long-term and disabling neurologic injury prior to performing peripheral nerve blocks.( Brull R, et al. Disclosure of risks associated with regional anesthesia: a survey of academic regional anesthesiologists. Reg Anesth Pain Med. 2007;32:7-11)

It’s better to tell the patient the truth, and risk the following dialogue:

Anesthesiologist: “The risk of permanent nerve injury after this nerve block is very low, but it’s not zero. A ballpark incidence of the chance of permanent nerve injury to your arm (or leg) is one patient in 3,000.”

 Patient: “A one in 3000 chance that I could have permanent nerve injury? I don’t want to take that chance. Skip the block.”

Yes, you might lose the opportunity to do the block, but that’s what informed consent is all about. It’s your duty to explain the risks, the benefits, and the alternatives. In Hardman’s article, the author states that he circles the words “nerve injury” on the anesthesia consent for peripheral nerve block, and he has the patient write their initials next to it, to document that they have read it and understand the risks.



  2. Liu SS, et al. A prospective, randomized controlled trial comparing ultrasound versus nerve stimulator guidance for interscalene block for ambulatory shoulder surgery for postoperative neurological symptoms. Anesth Analg. 2009;109:265-271).
  3. Brull R, et al. Disclosure of risks associated with regional anesthesia: a survey of academic regional anesthesiologists. Reg Anesth Pain Med. 2007;32:7-11.


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