Peripheral nerve damage and regional anaesthesia

Looking Back, Moving Forward in Pain Medicine

Pain is an ancient medical complaint and a clinical riddle that has never been entirely solved. Looking back into history was the springboard to a look into the future of pain medicine. This article was based on a series of presentations given in a recent congress (May 2023) and represents the research, views, and opinions of the authors. Opium has been used for millennia to treat pain, but when it gained broad use in the United States in the 1980s and 1990s, it was so vastly overprescribed and mis-prescribed that it led to a public health crisis. This, in turn, led to the reaction where opioids at times were under-prescribed, leaving out many patients who may have benefited from opioids while leaving many legacy pain patients to manage withdrawal on their own and with few analgesic options. Cannabinoids (CB) were likewise widely used for various conditions, including pain, but were outlawed in the 20th century, only to be brought back as a potential analgesic agent. Interventional pain medicine is a developing discipline and has reinforced the concept of the interdisciplinary pain clinic. It plays an increasingly important part in modern medicine overall, especially with the support of ultrasound, for both diagnosis and therapy. Today, the views about pain have changed. Anyone has accepted that pain is not purely a physical phenomenon but a biopsychosocial phenomenon that occurs within a cultural context. Pain management remains a small but vitally important medical subspecialty that is critical from a functional enablement and population health perspective, which is helping to navigate new therapeutic targets, new drugs and routes of administration, greater understanding of pain psychology, and new technologies. Pain control today means early intervention, functional enablement through pain alleviation, educating patients about pain management, and minimizing the transition from acute to chronic pain.

Is there still a place for the use of nerve stimulation?

The introduction of nerve stimulation as a method of nerve localization sparked a new beginning in regional anesthesia. It was an epochal development akin to the utilization of ultrasound in more recent times. Many experts now consider ultrasound-guided peripheral nerve blockade to be more efficient, less painful, and more successful than landmark and nerve stimulation techniques. However, inadvertent intraneural injection continues to occur despite the widespread use of ultrasound and nerve stimulation. Both of these technologies allow for only limited elucidation of needle position relative to the target nerve and are unable to reliably identify intraneural position of the needle. This article will review the role of nerve stimulation in modern regional anesthesia techniques in light of the introduction of ultrasound technology.

Complications of peripheral blockade

The wide variety of peripheral blocks makes for a difficult endeavor in trying to grasp their many potential complications. However, the common features of these complications makes it possible to use the construct presented here, in combination with one's knowledge of anatomy, to be able anticipate many, if not most, of the complications of any particular peripheral regional anesthetic.

[Different types of nerve injuries in locoregional anesthesia]

Neural damage is a possible complication of central nerve blockade and regional anaesthesia. Damage may be caused by ischaemic, mechanical or chemical mechanisms, which may occur either alone or in combination. Neural ischaemia may be caused by 1) prolonged and severe arterial hypotension, which compromises blood supply to the cord, 2) a spinal haematoma whose main etiological factor is a coagulation abnormality and 3) an intraneural injection. Mechanical trauma by the needle bevel is an important factor of neuropathy, particularly when searching for paraesthesiae. Neurological complications may also result from a direct neurotoxic effect of local anaesthetic agents which is concentration and dose-dependent. Better understanding of these mechanisms will permit the establishment of reliable bases for new preventive strategies.