The supratrochlear nerve block is a special procedure, which can be utilized to relieve pain in the mid-forehead region. It can provide anesthesia for complex laceration repairs and trigeminal neuralgia, among many others. Unlike local infiltration, this regional nerve block does not distort local anatomy and can achieve significant analgesia with a minimum amount of local anesthetic. There is some overlap with the supraorbital nerve block with regard to regional innervation and procedural location/technique. However, it is still a unique block and worthy of discussion for Emergency and urgent care providers, plastic surgeons, neurologists, and others who treat patients suffering from painful conditions involving this area of the head/face.
Providers must possess adequate knowledge of the regional anatomy involved in this block to achieve analgesia. The supratrochlear nerve is a division of the trigeminal nerve, specifically the V1 (ophthalmic) branch. The trigeminal nerve divides into the ophthalmic (V1), maxillary (V2), and the mandibular (V3). Furthermore, the ophthalmic branch divides into the supraorbital nerve and the supratrochlear nerve. The supratrochlear nerve emerges 3 mm medial to the vertical line drawn from the apex of the lacrimal caruncle along the supraorbital margin. The nerve innervates the paramedian aspect of the forehead and occasionally the part of the eyebrow and internal angle of the orbit.
The supratrochlear nerve block indications include local anesthesia as needed for procedures or temporary pain relief in the following:
Contraindications for the supratrochlear nerve block include:
To perform the supratrochlear nerve block, the required equipment includes:
Providers need to discuss the risks and benefits of the procedure and document informed consent from the patient or alternative decision-maker/authority (i.e., the patient’s parent or guardian). Proper preparation includes having all necessary equipment and medication at the bedside. Providers, especially those new to this technique, may also find it helpful to review and map out or even mark the appropriate landmarks prior to infiltrating the anesthetic agent.
The following steps are used in performing the supratrochlear nerve block:
Complications vary in frequency, but may include:
The supratrochlear nerve block can help anesthetize a large area of the forehead without distorting the tissue, as would be the case with local infiltration. Moreover, it is an alternative to opioids or other pain medications.
The supraorbital nerve block is also frequently used to anesthetize the forehead and, as it innervates a larger portion of the forehead, involves a larger total area, including the periphery of the forehead/face. Performing a supratrochlear nerve block can help anesthetize the paramedian region of the forehead and, in conjunction with a supraorbital nerve block can anesthetize the entire hemi-forehead extending posteriorly to include the anterior portion of the scalp.
Interdisciplinary teams are essential to healthcare. Each member of the healthcare team should cooperate, and the team should operate seamlessly with each member knowing their role and working together to provide the best and highest level of care for each patient.
In many healthcare settings, nurses have the most face to face contact with the patient from triage/introduction to discharge. They can ensure that informed consent was obtained before any procedure. Nurses are often the first to notice abnormal vital signs, allergic reactions and medication side effects including rashes or changes in mental status and can take proactive action by placing them on appropriate monitors (i.e., cardiac or pulse oxygenation), double-checking the patient’s known allergies as well as whether the medication ordered was ordered with the appropriate dose. Their assistance before, during, and after nerve blocks is imperative to minimize adverse effects and complications from any procedure.
Likewise, pharmacy staff can be crucial to provide aid in the selection of alternative agents due to allergies and dosing of less commonly used medications or treatments, such as lipid emulsion, especially in the case of adverse events such as local anesthetic systemic toxicity (LAST). The amount of local anesthetic used, particularly in small regional nerve blocks like the supratrochlear nerve, is so little that concern for LAST is quite minimal.
Physicians and non-physician providers (i.e., nurse practitioners and physician assistants) are usually the members of the healthcare team who will perform the supratrochlear nerve block and any related procedures (i.e., laceration repair) if necessary depending on the indication. They are ones who will be held primarily responsible for any significant complications or adverse events. Good communication practices between physicians, team members, patients, and the patients’ families are essential for optimal patient outcomes and promote a culture and commitment to patient and provider safety.
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