Chiropractic care frequently uses spinal manipulation, a procedure involving a high-velocity, low-amplitude thrust applied to a joint to improve mobility and function. This technique is often sought to address musculoskeletal pain, particularly in the spine. Given the proximity of the spine to the nervous system, a common concern is whether this physical intervention can lead to nerve damage. While spinal manipulation is generally considered a low-risk procedure, the potential for serious complications, including nerve injury, requires a detailed understanding of the mechanisms and safety protocols involved.
Understanding the Risk Profile
The risk of experiencing severe, permanent nerve damage following a spinal manipulation is statistically low when compared to the total number of procedures performed annually. Minor and temporary side effects are relatively common, with approximately 35% to 66% of patients reporting transient symptoms such as localized stiffness, muscle soreness, or mild headache immediately following an adjustment. These effects are typically short-lived, resolving within 24 to 48 hours as the body adapts to the changes. The most serious complication associated with cervical spine manipulation is a stroke resulting from vertebral artery dissection (VAD). Estimates for this event vary widely in the literature, ranging from approximately 1 in 20,000 to as low as 1 in 5 million adjustments. Injuries to the peripheral nervous system, such as nerve compression or radiculopathy, are also extremely infrequent, with one estimate placing the risk at about 1 in every 50,000 chiropractic visits.
Mechanisms of Potential Nerve Damage
Neurological injury from spinal manipulation can occur through several distinct physical pathways, primarily involving the mechanical forces applied during the procedure. One of the most discussed mechanisms is vascular compromise, specifically the dissection of the vertebral or carotid arteries in the neck. The high-velocity thrust of a cervical adjustment can, in rare instances, cause a small tear in the inner lining of an artery wall. This tear can lead to a blood clot forming at the site, which may then travel to the brain, resulting in a stroke and subsequent neurological deficit.
Another pathway involves the direct mechanical compression or traction of a nerve structure. This risk is elevated in the presence of pre-existing, undiagnosed spinal conditions. If a patient has a substantial space-occupying lesion, such as a large, acute herniated disc, the force of the adjustment could potentially worsen the disc protrusion. This can increase pressure on the spinal nerve root, leading to severe radiculopathy, or in the lumbar spine, potentially compress the cauda equina nerve bundle, a medical emergency.
Beyond the major structures, excessive mechanical stress can also cause injury to specific peripheral nerves. Cases have been reported where the force or stretch applied during a neck adjustment resulted in damage to nerves like the phrenic nerve or the spinal accessory nerve. In all cases of serious neurological injury, the damage is typically a result of the procedure interacting with an underlying, often asymptomatic, vulnerability in the patient’s anatomy.
Screening and Risk Mitigation Protocols
Chiropractors employ comprehensive screening protocols to identify patients who may be at an elevated risk for neurological complications before administering treatment. The process begins with a detailed patient history, which is used to uncover pre-existing conditions that may contraindicate spinal manipulation. Conditions such as severe osteoporosis, inflammatory arthritis, spinal cancer, or a recent history of vascular events are all considered significant risk factors. The practitioner then screens for “red flags,” which are specific symptoms that suggest a serious underlying pathology requiring immediate medical referral rather than manipulation.
These flags include:
- Unexplained weight loss
- Fever
- Night pain
- Progressive neurological deficits like foot drop or rapidly worsening weakness
A thorough physical and neurological examination is also performed, which involves testing reflexes, muscle strength, and sensation patterns to assess the integrity of the nervous system. Specific orthopedic tests, such as those designed to challenge the cervical arteries, are often performed, although it is recognized that no single in-office test can definitively rule out a vertebral artery dissection.
If any of these screening steps suggest an elevated risk—for instance, if the patient reports symptoms indicative of vertebrobasilar insufficiency—the manipulation procedure is considered inappropriate. In such cases, the chiropractor will modify the treatment plan, use a gentler technique, or refer the patient to another medical specialist.
What to Do If Symptoms Occur
Patients must be aware of specific warning signs that necessitate immediate medical attention following a spinal manipulation. Any sudden, severe headache—often described as the “worst headache of your life” or a thunderclap headache—is a serious warning sign of a potential vascular event. Neurological signs such as sudden weakness or numbness on one side of the body, facial drooping, or difficulty lifting an arm are classic indicators of a stroke. These symptoms, particularly when combined with dizziness, slurred speech, or vision changes, require an immediate trip to the emergency room or an immediate call for emergency medical services.
Additionally, the sudden onset of bladder or bowel incontinence, combined with severe low back pain or numbness in the saddle area, is a sign of cauda equina syndrome. This condition is a surgical emergency that requires immediate intervention to prevent permanent paralysis. For less severe symptoms, such as persistent numbness, tingling, or increased localized pain that does not begin to resolve within 24 to 48 hours, the patient should contact their chiropractor or primary care provider for a follow-up assessment.