Strangulation involves external pressure applied to the neck, compressing the delicate structures within. This action can impede normal breathing or the circulation of blood to and from the brain.
Mechanisms of Neck Compression
Strangulation inflicts harm through three mechanisms that disrupt bodily functions. The immediate impact often stems from vascular compression, affecting both the arteries that supply blood to the brain and the veins that drain it. Pressure on the carotid arteries, located on either side of the neck, restricts the flow of oxygen-rich blood to the brain, leading to cerebral ischemia, or a lack of blood supply. Simultaneously, compression of the jugular veins prevents deoxygenated blood from leaving the brain, causing blood to pool and increasing intracranial pressure. This dual effect on cerebral blood flow rapidly contributes to oxygen deprivation in brain tissue.
Another mechanism is airway obstruction, which occurs when pressure is applied to the trachea, or windpipe. When compressed, the trachea restricts or completely prevents air from entering the lungs, leading to asphyxia. This lack of oxygen intake further exacerbates the brain’s oxygen deprivation.
Beyond vascular and airway effects, strangulation can also involve nerve stimulation. The neck contains the vagus nerve and carotid sinus, both of which are sensitive to external pressure. Stimulation of the carotid sinus reflex can trigger a sudden drop in heart rate (bradycardia) and blood pressure (hypotension). This reflex response can contribute to a rapid loss of consciousness, even if complete vascular or airway obstruction has not yet occurred.
Immediate Bodily Responses
The body reacts to neck compression, initiating physiological responses. A primary consequence is cerebral hypoxia or anoxia, which refers to insufficient or complete absence of oxygen reaching the brain, respectively. Reduced blood flow fueled by carotid artery compression and impaired venous drainage leads to a rapid depletion of oxygen in brain cells. This oxygen deprivation quickly impairs neuronal function and can lead to cellular damage.
As the brain becomes deprived of oxygen, loss of consciousness occurs quickly. This can happen within seconds to tens of seconds due to the brain’s high oxygen demand and its inability to store oxygen. The brain’s altered state due to hypoxia leads to a rapid progression from confusion to unconsciousness.
The severe oxygen deprivation can also trigger involuntary bodily reactions. These may include seizures, which are uncontrolled electrical disturbances in the brain, or loss of bladder and bowel control. Muscle twitching or involuntary movements can also occur as the brain is affected by hypoxic conditions.
The cardiovascular system attempts to compensate for the sudden disruption. Initially, changes occur in heart rate and blood pressure as the body tries to maintain cerebral perfusion. However, these compensatory mechanisms are quickly overwhelmed by sustained compression, leading to further deterioration.
Resulting Physical Injuries
Strangulation can leave physical marks, both externally visible and hidden internally, reflecting trauma to the neck’s delicate structures. External signs include:
Bruising, which may appear immediately or develop over hours to days.
Ligature marks, if an object was used, indicating the shape and material of the compressing force.
Petechiae, tiny pinpoint hemorrhages, observed on the face, eyelids, and in the whites of the eyes (subconjunctival petechiae). These occur due to increased venous pressure in the head and neck as blood cannot properly drain from the brain.
Swelling of the neck or face.
Internal injuries are important to note because they may not always correlate with the presence or severity of external signs. Structures such as the larynx (voice box) and trachea can be damaged, potentially leading to voice changes or difficulty breathing. The hyoid bone, a small, U-shaped bone, or the thyroid cartilage can also sustain fractures. Damage to blood vessels, such as carotid or vertebral artery dissection or rupture, can occur, which may lead to delayed complications like stroke.
Critical Timelines
The speed at which events unfold during strangulation underscores its danger. Loss of consciousness occurs rapidly, often within 7 to 10 seconds of sustained compression. This swift onset of unconsciousness is primarily due to the immediate deprivation of oxygen to the brain. Even if the compression is released quickly, the individual may experience a period of confusion following the regain of consciousness.
Irreversible brain damage can begin to occur within minutes if oxygen deprivation persists. Neurological injury is possible after only a few minutes without adequate blood flow and oxygen to the brain. The brain’s cells are sensitive to oxygen levels, and prolonged hypoxia can lead to permanent cognitive and physical impairments.
Fatal outcomes can result from sustained compression, with death potentially occurring within one minute. The rapid progression from consciousness to unconsciousness and then to irreversible brain damage highlights the life-threatening nature of any form of strangulation.