Cortisone injections are a common medical procedure used to treat inflammation and pain in the foot and ankle, delivering a powerful anti-inflammatory corticosteroid, often combined with a local anesthetic, directly to the source of discomfort (e.g., plantar fasciitis, arthritis, or Morton’s neuroma). While the procedure is routine and generally safe, the foot contains numerous nerves, making accidental contact a known, though rare, potential complication. Understanding the signs and subsequent care is important for anyone undergoing this treatment.
Immediate Signs of a Nerve Encounter
The most immediate and distinct sign that the needle has encountered a nerve is a sudden, intense sensation that feels like an electric shock. This powerful, involuntary reaction often causes the patient to flinch or pull the foot away instantly. The pain is typically described as shooting or stabbing, radiating sharply down the foot or into the toes along the path of the affected nerve.
This initial electrical sensation is caused by the mechanical stimulation of the nerve bundle by the needle tip. Following this acute pain, the patient may experience immediate, temporary neurological changes, such as numbness or weakness in the foot or toes. These symptoms result from the nerve being abruptly agitated or compressed.
The introduction of the injection fluid, which contains the corticosteroid and a local anesthetic, can also cause an intense burning or tingling sensation, medically known as paresthesia. This chemical irritation can occur even if the needle did not directly puncture the nerve sheath. If the sensation is severe, the clinician should immediately withdraw and reposition the needle before proceeding with the injection.
Distinguishing Irritation from Injury
A transient encounter between the needle and a nerve typically results in temporary irritation, which is distinct from a lasting injury. This temporary trauma is often caused by the mechanical pressure of the needle or the volume of the injected fluid compressing the nerve tissue. Symptoms from this type of irritation usually begin to resolve quickly, often within minutes to a few hours after the procedure.
A true, lasting nerve injury involves damage to the nerve fibers themselves, which is a very uncommon event. The risk of this injury is highest if the injection fluid is delivered intrafascicularly, meaning directly into the nerve’s internal structure. Some corticosteroid agents have been shown to have a neurotoxic effect when injected directly into the nerve.
The duration of symptoms is the primary factor in distinguishing between irritation and injury. With irritation, the electric or shooting pain sensations subside rapidly, and any residual tingling or numbness disappears as the local anesthetic wears off. A potential nerve injury, however, is suggested by persistent or worsening symptoms that continue beyond 24 to 48 hours after the injection. This persistent pain, numbness, or motor weakness indicates that the nerve may have sustained significant trauma requiring specialized care.
Necessary Medical Management and Recovery
Immediate post-injection management for a suspected nerve encounter begins with protecting the foot and minimizing potential secondary damage. Patients should rest the foot and avoid placing excessive pressure or weight on it for the first one to two days. Applying ice to the injection site can help reduce localized swelling and inflammation, soothing the irritated nerve.
It is necessary to contact the prescribing physician immediately if certain symptoms develop or persist. Signs that necessitate urgent follow-up include foot drop (the inability to lift the front part of the foot) or a complete loss of sensation in a specific area. A pain that drastically increases in intensity after the initial local anesthetic has worn off is also a warning sign.
For mild nerve irritation, the recovery timeline is typically short, with symptoms often fading over a few days to a couple of weeks as the nerve sheath recovers from the temporary shock. If a true nerve injury is confirmed, the management pathway is more involved and may begin with medications designed to treat nerve pain. Further treatment could include physical therapy to maintain muscle strength and mobility. In some cases, specialized nerve testing, such as electromyography, may be used to assess the extent of the damage and guide the long-term recovery strategy.