Occipital Pressure Injury in the Beach-Chair Position Is a Strap-Tension Phenomenon: A Two-Patient Case Report and Review of Literature

When a surgeon needs to repair a shoulder, they often place the patient in a position that mimics sitting upright in a chair, with the head resting on a padded support. This setup, known as the beach-chair position, offers the surgeon a clear view and easy access to the joint. However, keeping a person still in this upright posture for hours creates a unique physical challenge for the back of the head. The skin and nerves at the base of the skull are delicate, and if they are pressed too hard against a hard surface for too long, the blood flow can be cut off. This can damage hair follicles, causing patches of hair to fall out, or it can pinch the nerves that carry sensation from the scalp, leading to numbness. While surgeons have long known that these injuries can happen during long, flat-on-back surgeries, they generally believed that the upright beach-chair position was safer because gravity pulls the head away from the support rather than pressing it down.

Two doctors at King's College Hospital and Ashford and St Peter's Hospitals decided to test this assumption after noticing that two patients had suffered these exact injuries despite being in the upright position. The first patient, a 53-year-old man, had a shoulder surgery that lasted 92 minutes. He woke up with a distinct, hairless patch on the back of his head. The second patient, a 24-year-old man, underwent a longer procedure lasting 180 minutes. He woke up with persistent numbness and tingling on the side of his head, a sign that a nerve had been compressed. Both men were healthy, their blood pressure remained stable throughout the operations, and their heads were positioned straight without any twisting. They were lying on a modern, padded headrest that was widely considered safe, yet they still developed injuries.

The researchers realized that the usual explanations for these injuries did not fit. Typically, hair loss or nerve damage is blamed on low blood pressure, which starves the tissue of oxygen, or on the head being twisted to one side, which concentrates pressure on a small spot. In these two cases, neither factor was present. The patients' blood pressure was normal, and their heads were aligned perfectly straight. This forced the team to look closer at how the head was actually being held in place. In the upright position, the head does not rest heavily on the pad due to gravity; instead, it is held against the pad by straps that go over the forehead and under the chin. The doctors proposed that these straps were the true culprit. They suggested that the tension from tightening the straps to keep the head from slipping forward was pressing the back of the skull into the headrest with enough force to cause injury, regardless of how soft the padding felt.

To understand why this matters, one must look at the difference between lying flat and sitting up. When a person lies on their back, their own head weight presses down on the support. When they sit up at an angle of about 80 degrees, gravity pulls the head backward along the spine, so very little of its weight actually presses into the cushion. In this upright state, the only thing pushing the head firmly into the pad is the force of the straps holding it there. If the straps are pulled too tight, they create a strong, focused pressure on the skin and nerves at the back of the head. This pressure can be high enough to block blood flow to hair follicles or compress the nerves, even if the surgery is relatively short and the patient is otherwise healthy. The researchers noted that while the padded cradle used in the hospital was better than a hard, horseshoe-shaped rest, it was not enough to stop the injury if the straps were pulling the head too hard against it.

The team reviewed similar cases in medical literature and found that injuries to the nerves on the side of the head had been reported with many different types of headrests, from rigid plastic rings to soft foam pads. This pattern suggested that no single design of headrest could guarantee safety on its own. The common thread was the mechanical force applied to the head. In the upright position, that force comes primarily from the straps. The researchers emphasized that this was a hypothesis based on their observations and the mechanics of the situation, as they did not have a way to measure the exact pressure inside the headrest during the surgeries. However, the fact that injuries occurred in patients with no other risk factors strongly pointed to the straps as the missing piece of the puzzle.

In response to these findings, the hospital unit changed how they prepare patients for shoulder surgery. They now add extra layers of soft foam padding over the standard headrest to spread the pressure out more evenly. They also instruct the team to tighten the forehead and chin straps just enough to keep the head from sliding, but not so tight that they indent the skin. The anesthesiologists check the head's position every 30 minutes and gently lift and reposition it whenever the surgeon allows, especially if the operation goes on for more than two hours. They also make sure to check the back of the head after surgery and ask patients specifically about numbness or hair loss. Most importantly, they now tell patients about these risks before the surgery begins, so that if a patient wakes up with a numb spot or a bald patch, they understand it is a known complication of the position and not a sign of a more serious brain injury.

The doctors concluded that while these injuries are rare, they are preventable. The key is to recognize that in the upright beach-chair position, the straps are doing the heavy lifting, not gravity. By loosening the straps slightly and adding extra cushioning, the medical team can reduce the pressure on the back of the head. They cannot promise to eliminate the risk entirely, as every patient's body is different, but these simple adjustments make the surgery much safer. The story of these two patients serves as a reminder that even in modern medicine, the way we hold a patient still can have unexpected consequences, and that paying attention to the small details of positioning can prevent real harm.