Dr. Adams' Alabama Headache Blog

A recent abstract discussing The Jolt Syndrome, The Muscle Dysfunction Following Low-Velocity Impact. Pain Manag, Nov/Dec 1990.

Despite involving forces insufficient to cause tissue injury, many low velocity collisions and occupational accidents result in pain and sometimes disability. This article proposes that the underlying mechanism in this dysfunctional state is an unusual sustained positive feedback loop, flowing from the proprioceptor in the muscle spindle and joint capsules to this neuologic circuit, an increase in muscle tension and an imbalance in the motor position of the jolted muscles.

This study used a three pronged approach. The office archives were carefully evaluated for appropriate cases. A review of the literature was conducted. Consultation with a varied group of basic and chemical scientists and back care providers was also included. The premise of this study was that there can be pain without specific injury. Myofascial structures can be made painful without injury when stretched into the supra-physiologic stretch reaction or suddenly reflexly contracted.

Muscle spindles are encapsulated muscle fibers connected to or ensheathed in windings of sensory fibers and innervated by small efferents. There are twelve of these in each muscle. The tension of the intrafusal muscle fibers is set by the gamma efferent and it is this tension that determines the sensitivity of the local extrafusal muscle fibers to stretch. Experiments with cats have indicated that gamma efferents may be highly responsive to very small disturbances as rapid stretching of partially contracted muscles occurs. Work with muscles of cats demonstrates a powerful synaptic activity among interneurons associated with ascending tracts, as well as spinal reflex pathways. This indicates that a flurry of afferent discharge from the spindles may reflexly generate exaggerated sensitivity to stretching. Evidently, the more structurally compromised a tissue, the less force necessary to cause systematic disruption.

Despite involving forces insufficient to cause tissue injury, many low velocity collisions and occupational accidents result in pain and sometimes disability. The mechanism proposed is a positive feedback loop, flowing from the proprietory in muscle spindles and joint capsules. The effects of this neurologic circuit are an increase in muscle tension and an imbalance in the motor patterns of the jolted muscles. Treatment should focus on reestablishing dynamically efficient motor patterns via properly selected exercises and posture training.