An occipital nerve block (ONB) is a non-surgical treatment used to manage pain from headache disorders, including migraines, cluster headaches, and occipital neuralgia. This minimally invasive procedure involves injecting medication near the occipital nerves, located at the base of the skull. The goal is to interrupt pain signals and reduce inflammation, offering temporary relief for head and neck pain. Understanding the potential risks and side effects is necessary when considering this generally safe and effective option.
The Occipital Nerve Block Procedure
The occipital nerves (greater and lesser) originate from the upper cervical spinal nerves and provide sensation to the back of the scalp. Irritation or inflammation of these nerves causes pain that radiates across the head. The nerve block targets this area for relief.
The procedure occurs in a clinic with the patient seated or lying down. After cleaning the skin, the provider locates the nerve using anatomical landmarks or ultrasound guidance for accuracy. The injection solution typically contains a local anesthetic (e.g., lidocaine or bupivacaine) to numb the area. A corticosteroid may be added for longer-lasting anti-inflammatory effects.
The needle is carefully inserted near the nerve, and the medication is slowly injected. The entire process usually takes only a few minutes. The local anesthetic begins working immediately, and some patients feel pain decrease within minutes. Patients are monitored briefly before going home.
Expected Temporary Side Effects
Patients should anticipate common, temporary reactions related to the injection or medication effects. The most frequent is mild pain, soreness, or tenderness at the injection site. This discomfort is due to the needle insertion and usually resolves within one to three days.
Minor bruising or localized bleeding may occur where the needle penetrated the skin. The local anesthetic causes temporary numbness in the treated scalp area, which is expected and typically wears off within two to six hours.
Some people experience brief lightheadedness, dizziness, or vertigo shortly after the procedure, often due to the anesthetic spreading or a temporary drop in blood pressure. If a steroid is used, temporary facial flushing or warmth may occur. Rarely, localized skin changes, such as temporary hair loss (alopecia) or skin thinning (atrophy), can happen at the injection site.
Rare and Serious Risks
Occipital nerve blocks are generally safe, but serious risks require immediate medical attention. A significant risk is infection, which can be localized or, rarely, systemic. Signs of infection include increasing pain, warmth, spreading redness, or swelling at the injection site, especially if accompanied by a fever.
There is a small risk of nerve injury or damage, manifesting as prolonged or new burning pain, weakness, or persistent tingling. Vascular injury can occur if the needle enters a blood vessel, such as the occipital artery. Providers mitigate this risk by performing aspiration before injection to ensure the needle is not inside a vessel.
Rarely, allergic reactions to the anesthetic or steroid may occur. Severe allergic signs include trouble breathing, sudden facial or throat swelling (facial edema), or a significant drop in blood pressure. Patients with diabetes should note that the corticosteroid can cause a temporary elevation in blood sugar levels lasting up to two weeks.
A transient worsening of the original headache is sometimes reported immediately after the procedure. In extremely rare instances, if the medication travels into the subarachnoid space, it can lead to brain stem anesthesia or unconsciousness. Any severe or persistent headache, vision changes, or prolonged weakness or numbness beyond the anesthetic effects should be reported immediately.