Nerve damage seems to be the most common serious injury (as opposed to minor injuries like rope marks, bruising, etc) that occurs in bondage scenes.
Nerve damage is much more of a concern for bondage than decreased circulation (though the two can and do happen concurrently).
Danger signs for nerve damage include pain (generally described as sharp/shooting), weakness, tightness, stress, tingling, and numbness. These generally occur QUICKLY, sometimes instantly, and should be acted on immediately to prevent long term damage.
Nerve damage can occur either by stretching of the nerve (ex: over-extending the arms over the head for extended periods of time) or by compression (ex: rope pressing tightly up against the armpit)/shearing force (ex: tight rope pulling across the upper arm). Shearing force refers to parallel surfaces sliding past one another and is particularly problematic for your nerves – if you ever had a gradeschool classmate do a “snake bite” on your arm, you have some idea of what this type of force feels like.
- Individual differences in nerve vulnerability.31 Some people seem to have bombproof nerves, some people seem to get nerve damage if you look at them funny
- Anatomical location: where on the body you are tying. Some locations are higher risk than others. For example, joints and upper arms are generally higher risk areas, as compared to the thighs or ankles31
- Duration of compression. Nerve damage happens in stages – removing bondage at the first signs of injury can keep a minor injury from becoming a major one.1
- Severity of compression/amount of shearing force.1 The increased severity of compression and risk of shearing is part of what makes suspension bondage generally higher risk than floor work.
- Stretch/stress positioning. This also has a lot of individual variance. Keep in mind that stretching/stress positioning may also make nerves more vulnerable to compression.
- Environment (internal & external)
Most incidents of nerve damage involve many (if not all) of these 6 factors.
As a general rule: The more force and the longer the time, the greater the damage will be. “Mechanisms of nerve injury include direct pressure, repetitive microtrauma, and stretch- or compression-induced ischemia. The degree of injury is related to the severity and extent (time) of compression.”1
It’s possible for nerve damage to occur without any warning/symptoms at all, and even with an experienced top who does “everything right.”
Nerve irritation that is immediately resolved leads only to temporary nerve damage (numbness that goes away quickly). Any prolonged irritation can lead to semi-permanent damage (nerves need weeks or even months to heal!) or to permanent loss of function. “Recovery of nerve function is more likely with a mild injury and shorter duration of compression.”7