Strangulation injuries are a heterogeneous set of traumatic pathology that occurs as a result of mechanical force applied externally to the neck and surrounding structures. As a type of asphyxia, these injuries may result in decreased cerebral oxygen delivery either by compression of cervical blood vessels, or tracheal occlusion. Death rapidly ensues without the removal of compressing forces. Should a patient survive the initial injury, care must be taken to evaluate for occult injury. External signs of injury, or lack thereof, may underrepresent the extent of deeper damage. The term “choking” is colloquially used to describe these injuries, however more accurately this term when used medically suggests an internal occlusion or partial occlusion of the proximal airway.

Patients who suffer from these injuries also represent a high-risk population in regards to a variety of biopsychosocial sequelae. Domestic and other types of violence unfortunately represent a significant percentage of these injuries year-over-year.[1][2] Additionally, it is a common injury pattern seen in completed suicide and suicide attempts. History and toxicological analysis of these patients sometimes reveal various substances, either intentionally ingested or otherwise.[3] Strangulation injuries can also occur as a result of both consensual and non-consensual sexual activity.[4] Martial arts, combat sports, military training, and law enforcement action are implicated as well – certain holds and detainment maneuvers may call for external neck compression.[4]

Pediatric populations are particularly vulnerable not only because of anatomic differences but because of downstream psychosocial issues that put them at high risk for morbidity and mortality should they survive the initial injury.[5][6] Additionally, social media and other outside media influences have been reported as a social stressor leading to suicide attempts in adolescent populations.[7][8]

Identification, diagnosis, and treatment require a multi-disciplinary approach. Once medical evaluation and treatment are underway, simultaneous mobilization of mental health experts, social workers, and law enforcement (depending on the clinician's jurisdiction) must occur. Other personnel and approaches may be required as well depending on the individual injury pattern and psychosocial milieu. Criminal implications exist on the autopsy of patients who have succumbed to these injuries as well.

Strangulation is defined as the compression of blood or air-filled structures which impedes circulation or function. In this summary, strangulation will refer to compression of anatomical neck structures leading to asphyxia and neuronal death. Strangulation injuries can be divided into several categories. These include hanging injuries, manual strangulation, and ligature injuries.[9][10][11][12]

Hanging injuries can be further divided into specific categories. Complete hanging is defined by the full weight of the patient being suspended by the neck. Incomplete hanging injuries encompass all injuries in which the patient is supported partially by another object such as the ground or furniture. For centuries hanging has been used in the penal systems as a form of punishment. The term “well-hung” referred to the erection a male experienced after a proper hanging was performed. This method of execution usually involved dropping the person from a height equal to or greater than their height, which often resulted in spinal fractures, spinal trauma, and spinal shock causing priapism.[13] Classically, hanging injuries have also been associated with vascular pathology ranging from carotid intimal tears to complete rupture.[14]

Ligature and manual strangulation injuries occur when a force that is independent of the patient’s body is applied to the neck. Strangulation injuries can also be divided into categories of intent. These include homicidal, suicidal, accidental, and auto-erotic.[2][15] The material involved in a ligature or hanging may also have implications on pathology and subsequent forensics.[16]

A significant number of pediatric strangulation injuries are accidental.[6] The unique behavioral characteristics of different ages highlight the mechanisms among these injuries and deaths. Younger children may suffer from injuries related to car windows, electrical cords, and becoming trapped between furniture (including high-chairs designed for children).[17][18] Accidental or intentional suffocation injuries, a mechanism distinct from strangulation via which asphyxia occurs due to oral-nasal obstruction, may also be part of the presenting situation.[16] Playground and handle-bar strangulation injuries, while rare, are important etiologic factors to consider in polytrauma pediatric patients with supporting histories.[19] As mentioned earlier, social media influences play a critical and more contemporary role in teenage and adolescent populations. The literature describes auto-erotic asphyxiation as a more common mechanism in this population as well and constitutes a mechanism of injury that can be considered both intentional and accidental. 

Strangulation injuries can occur during partnered sexual activity – either intentionally, accidentally, or both. It is a dangerous form of intimate partner violence, and survivors are at high risk for becoming victims of homicide.[20] Conversely, consenting adults engaging in low-force activity to enhance pleasure may sustain devastating injuries if care is not taken. Additionally, auto-erotic asphyxiation is seen in the adult population of strangulation injuries and is described as a paraphilia.[21]   

Many “submission holds” within the world of martial arts are known to place direct pressure on cervical structures and can result in strangulation injuries. Along similar lines, police and military combatants are given training on "vascular neck restraint." This effective, but controversial, approach to subduing a target can result in permanent and debilitating injuries or even death.[22]

The true prevalence and incidence of all-cause strangulation injuries and mortality is unknown. Because of the diversity of etiologies that lead to the common injury pathway, epidemiological studies, and case series within the literature tend to be etiology and population specific. 

Hanging injuries are the second most common cause of suicide in the United States; whereas, gunshot wounds are the leading cause. Males are more likely to commit suicide in both of these manners.[23] Women in abusive relationships are at the greatest risk of strangulation injury. Epidemiological studies and medical literature may underrepresent the true incidence and prevalence due to patient underreporting when medical attention is sought.[2] The incidence of hanging injuries has been increasing in the United States over the past several years, though as a cause of death in homicide cases it has remained fairly unchanged from 2006-2013.[3] The popularity of “choking games” amongst pre-teens and teens has also affected the escalation of these injuries.[24]

In a retrospective case series published by Berke et al (2019), 98 near-hanging patients were identified over an 11-year period. All patients underwent trauma evaluation, and 254 CT and MRI scans were performed, which discovered only 8 traumatic injuries. Two patients demonstrated injuries to the cervical vasculature, three patients showed signs of thyroid cartilage and hyoid bone fractures, and three patients had vertebral injuries. A total of 35.7% of patients had clinically diagnosed anoxic brain injury, which was deemed present in all 19 patients who expired (19.5%). Injuries were more common in patients with a low Glasgow Coma Scale (GCS) compared with those exhibiting a normal GCS.[25] 

Pediatric patients less than 1 year of age unintentional strangulation injuries ranks fourth among all causes of unintentional injury. Motor vehicle accidents, drownings, and burns are all more common. Of over 200,000 playground injuries recorded in 1999, only 0.07% were fatal, and of these 50% were determined to be caused by asphyxia from strangulation injuries. Eighty percent of victims were found to be under 10 years of age.[6]

The common pathway through which strangulation injuries cause morbidity and mortality is via cerebral hypoxemia and resultant cerebral ischemia. Four specific pathways are described in the literature.[26]

1. External pressure to the jugular veins prevents adequate venous return from the cerebral circulation. Backpressure prevents eventual arterial inflow and results in elevated intracranial pressures. This ultimately results in unconsciousness, depressed brainstem functions, and ultimately asphyxia and death.
2. External pressure to the carotid arteries directly prevents oxygenated blood flow to the cerebral vasculature which leads to asphyxia and death.
3. Pressure obstruction of the larynx primarily results in the inability to oxygenate the pulmonary vasculature. Systemic hypoxia quickly ensues of which the most pronounced effects are rapid loss of consciousness followed by death.
4. Though rare, cardiac dysrhythmias may occur with pressure directed towards the carotid bodies bilaterally. This has the potential to evoke cardiac arrest, and subsequent death if not promptly recognized

Acute sequelae of rapid (or slow) loss of perfusion include various forms of anoxic brain injury. Watershed infarcts can occur in patients with chronic cerebrovascular disease. Ultimately, with a significant initial injury, diffuse cerebral edema can result which may lead to various forms of brain herniation and death. Diffuse axonal injury has also been described in the autopsy literature.

Pathophysiologic phenomenon can also be grouped in relation to the aforementioned three categories of strangulation - hanging, manual strangulation, and ligature-based injuries.

The nature of the hanging injury informs the type of pathophysiology. Judicial hangings from height can result in rapid deceleration mechanisms. Mechanical forces transmitted in this manner can result in what is described as “internal decapitation” – spinal cord transection, cervical vascular transection, and various types of spinal fractures. Classically, the "hangman's" fracture is described when deceleration causes forceful extension of the neck resulting in bilateral C2 pedicle fractures. If the force is severe enough C2 can become severely subluxated from C3, thus threatening the spinal cord. Associated hematomas may also result in neurological compromise. These fractures have been described in motor vehicle accidents where the top of the steering wheel immediately halts the forward movement of a patient's neck (should an airbag not be present) resulting in a similar hyperextension injury. Manual strangulation or hanging without a significant height drop implies less deceleration force, and fractures are not typically common in this population. Many types of cervical spine injuries in these patients are described as unstable.[26][27]

Compression of the jugular veins results in acute death by causing cerebral hypoxia followed by loss of muscle tone. Once muscle tone is compromised, increased pressure is applied to both the carotid arteries and the trachea. Direct compression of the carotid arteries also leads to a decrease or loss of cerebral blood flow and brain death. The direct pressure on the carotid sinuses causes a systemic drop in blood pressure, bradycardia, and other arrhythmias. Consequences are anoxic and hypoxic brain injury death.

Ligature-based injuries can include focused force trauma to certain structures. Force applied over a smaller surface area may result in more pointed injuries rather than extensive and broader crush-type injuries. The type of ligature may also be important – barbed ligatures may cause penetrating trauma to various neck zones, and may even injure deep structures. All types of aerodigestive injuries must be considered in these patients. Fractures of the hyoid bones and thyroid cartilage result from a force directed towards these structures.[26]

A variety of spinal cord injuries are associated with strangulation and pathophysiology is directly related to the specific mechanism. Complete cord transection might be a sign of rapid deceleration injuries. Alternatively, injury to surrounding structures may threaten nearby neurological anatomy. Hematomas and injury-related edema have all been described as mechanisms that result in spinal cord trauma. Spinal cord ischemia may result from the disruption of vessels necessary to maintain perfusion. Care must be taken in the evaluation as mechanical forces and displaced surrounding structures may injure or disrupt spinal tendons and ligaments. The pathophysiology of these injuries is diverse and if severe can lead to paralysis and ultimately death.   

Facial and cervical petechiae and ecchymoses are a common injury pattern found in strangulation injuries. Pressure transmitted via compressed vasculature can result in capillary, venule, and arteriole injuries resulting in these skin findings. Facial plethora or swelling can occur due to the externally-applied pressure. Similar mechanisms result in ocular findings such as subconjunctival hemorrhages. Epistaxis from pressure has been described as well and is thought to be due to pressure-related vascular injury.[28]

Vascular trauma may include transection and intimal tears. These injuries can lead to chronic issues and possibly pseudoaneurysms and other vascular complications. Lower pressures are needed to occlude cervical veins, and higher pressure is required for cervical artery deformation. Thrombotic events may result, which can cause acute occlusion and/or embolic phenomenon.[3][26][28]

Histopathological implications of strangulation injuries are as diverse as the pathophysiology that underlies each specific type and the conditions present at the time of injury. Typical findings of anoxic brain injury can be expected. Cell damage can appear in as little as four hours and is dependent on the extent and duration of anoxia/hypoxia. Ischemic cell damage may result in primary necrosis of neurological structures, or a delayed fashion via apoptosis if the patient survives the initial insult. A "cloudy swelling" pattern of nuclear regions and a reduction in basophilic character to the nucleus have been described. Cytoplasmic shrinking and pyknotic nuclei are also potential injury patterns. At the 8-12-hour mark classic “red neurons” begin to appear.[29]

Higher metabolic rate and oxygen demand underscore the areas of the brain that are most easily affected by strangulation injuries. Watershed regions are at a particular risk as well. CA1 pyramidal neurons within the hippocampus are implicated in memory deficits seen in patients who survive. Within the cerebellum, the Purkinje cells are at higher risk of anoxic injury, which explains gait abnormalities sometimes seen in survivors. Arterial border zones in various areas of the brain may demonstrate “wedge-shaped” lesions, which may be seen on detailed neuroimaging as well.[29]

There are multiple forensic pathology considerations in this patient population as well. Excoriation marks on the face and various body surfaces may signal struggle either by the patient to remove a ligature or other object causing strangulation. They may also signify injury caused by a potential assailant. Burns and musculoskeletal trauma may be present on autopsy as well depending on the circumstances. The cause of death can be difficult to assess due to the multiple pathways that lead to the common pathophysiology of death in strangulation. For example, homicide victims who suffer strangulation injuries that were also found submerged in bodies of water might have signs of both strangulation and submersion injury. Both lead to hypoxia and eventually death, and thus determining a sequence of events might be difficult.[3]