What are possible complications of therapeutic injections to manage pain?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Neurological complications may result from systemic reactions or be due to specific procedures. For example, injuries to peripheral nerves may result from direct trauma including localized hematoma, compression by tourniquet, unintentional neural traction, compression due to positioning, or injection of an excessively high concentration of LA. Complications following subarachnoid or epidural injections can result from direct spinal cord or nerve root trauma, spinal cord compression by hematoma, or spinal cord ischemia.

Direct neural damage is most often reported with brachial plexus blocks. Direct intraneural injection often is attributed to the practitioner's negligence or lack of skill but can occur with highly skilled and experienced interventionists. Needles with a low bevel angle (< 45°) may contribute to a lower incidence of such complications. Postblock neuropathy can occur immediately after the block or within the first 7 days; however, recovery is common over the ensuing 2-3 months.

Accidental injection of LA into the subarachnoid space sometimes complicates paravertebral blocks aimed at addressing somatic or sympathetic neural structures, such as the stellate ganglion. If the level of anesthetic-induced spinal cord dysfunction is as high as C4, respiratory support, including artificial ventilation, may be necessary. Occasionally, withdrawal of 10-15 mL of cerebrospinal fluid (CSF) reduces CSF concentration of the misplaced LA. Hypotension also can result from unintentional extensive subarachnoid or epidural blockade, or in some cases, from paravertebral sympathetic or celiac plexus blockade.

Pneumothorax is a potential complication from thoracic paravertebral, supraclavicular brachial plexus, intracostal, and celiac plexus blocks. Occasionally, trapezius and other apically directed intramuscular injections also might lead to pneumothorax. Symptoms can develop within minutes but more often develop over several hours. Frequently, patients who experience injections that violate the respiratory space complain of tasting the anesthetic followed by hoarseness. Radiographic evaluation is obligatory in cases in which this complication is suspected.

Injection site hematomas are usually minor complications associated with the use of large needles having a dull bevel or hook, except in patients with a bleeding disorder or taking anticoagulant medications. Diagnosis is usually evident by subcutaneous extravasation of blood, and in some cases, neural deficit, which may be slow to resolve. In cases of localized hematoma, initial use of ice and pressure is warranted to slow or stop the bleeding. Occasionally, this complication may require ultrasound or other imaging studies to document the size and location of the hematoma.

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