Clinical Focus: Strangulation and Hanging Injuries

A 31-year-old male was brought in by ambulance after attempting to hang himself. He was found hanging from a tow rope in the back yard by his brother who immediately cut him down. He was unconscious when he was cut down and had been hanging for an unknown amount of time.

A common method for suicide, hanging presents EPs with the question of whether imaging is necessary.

A 31-year-old male was brought in by ambulance after attempting to hang himself. He was found hanging from a tow rope in the back yard by his brother who immediately cut him down. He was unconscious when he was cut down and had been hanging for an unknown amount of time. On EMS arrival he was noted to be groggy but awake and alert, breathing spontaneously with normal breath sounds. In the ED, his physical exam is notable for ligature marks on his neck (image 1). His voice sounds normal to you and to the patient.  You wonder if you should get a CT angiogram or if he needs just observation, or if he can be safely discharged soon.

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Background
Hanging was historically used as a method for execution. For this reason, hangings in the past were broadly categorized as judicial or non-judicial. Classically, a judicial hanging involved a ligature with careful knot placement directly below the occiput and a drop equivalent to the victim’s height with abrupt tightening of the ligature and complete suspension of the entirety of the victim’s body weight. When done properly, this resulted in forceful distraction of the head and neck from the body, high cervical fracture, complete cord transection, and death. Victims of judicial hanging are not patients who survive and present to the ED.

Non-judicial hangings are those that occur in homes and jails. They are usually not associated with any significant drop and frequently lead to incomplete suspension, with part of the victim’s body still in contact with the ground. For this reason, near-hangings are associated with very different pathophysiology and injuries than complete, judicial hangings. Other patients encountered in the ED may be survivors of manual or ligature strangulation with the forces applied to the neck being independent of the victim’s body weight. Postural strangulation is the term applied to compression of the anterior neck against a firm object and also involves the victim’s body weight. This is frequently the cause of accidental asphyxiation in children.

Epidemiology
Hanging is the second most common form of suicide in the United States after firearms, accounting for 23% of the over 34,500 suicides that occurred in the year 2007. This number is on the rise compared with prior years. More than half were aged 15-44 years1. The majority of hanging victims are males.  A history of drug or alcohol abuse is seen frequently among hanging victims, as is psychiatric illness2.

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The true incidence of manual strangulation is unknown. In 2009, 2.4% of murders were secondary to “strangulation” or “asphyxiation”1. Women are much more likely to be victims of strangulation assaults than men. Non-fatal manual strangulation is likely underestimated and under reported, especially in the setting of intimate partner violence. Incidences reported in the literature range from 10-68% for non-fatal strangulation in intimate partner violence3.

Pathophysiology
The relatively superficial and unprotected jugular veins in the neck are quite vulnerable to compression by external forces. Obstruction of venous outflow from the brain leads to stagnant hypoxia and loss of consciousness in as little as 15 seconds. The resultant decrease in muscle tone allows the external force to tighten further and leads to complete arterial occlusion, brain injury, and death. External compression of the airway structures requires significantly more force than the vascular structures and this is not thought to play a significant role.

Another proposed mechanism for the cause of death relates to vagal reflexes resulting from external pressure on the carotid body, which can lead to extreme bradycardia and cardiac arrest. The role of the carotid sinus reflex in strangulation and near hanging is disputed and believed to be relatively uncommon.

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Pulmonary sequelae are frequently seen in survivors of near-hanging and strangulation as well. These include pulmonary edema, aspiration pneumonitis/pneumonia, and adult respiratory distress syndrome (ARDS). Two mechanisms have been proposed as causes for pulmonary edema. Neurogenic pulmonary edema results from a centrally-mediated, massive sympathetic discharge after anoxic brain injury.

Post-obstructive pulmonary edema results from excessive negative inspiratory pressures generated by the victim’s attempts to forcefully inspire against an airway obstruction. Once the obstruction is removed, pulmonary edema develops and can rapidly lead to ARDS. Pulmonary complications are frequently responsible for delayed mortality in survivors of near-hanging and strangulation.

Clinical Features
Presenting signs and symptoms vary depending on mechanism. Common features include evidence of external pressure on the skin of the neck by the ligature, assailant’s hands, or other object causing strangulation. This may be as subtle as hyperemia or as obvious as ecchymosis or abrasions. Defensive marks may also appear on the neck in the form of abrasions/fingernail scratches. Petechial hemorrhages on conjunctiva, mucous membranes, and skin cephalad to ligature are another common feature (as shown in image 2). These are referred to as Tardieu’s spots and occur when the venous pressure rises as the ligature tightens resulting in congestion and capillary rupture. The same mechanism leads to subconjunctival hemorrhages.

Other frequently reported symptoms include voice changes (from hoarseness to aphonia), odynophagia, dysphagia, dyspnea, neck or throat pain, altered mental status and neurologic symptoms. In many cases, physical findings are completely absent in non-fatal strangulation.

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Diagnostic Considerations
Cervical spine fractures are well-documented in judicial hangings but are thought to be exceedingly rare or non-existent in non-judicial hangings. However, one retrospective case review of near-hangings over a 10-year period at LA County and University of Southern California Medical Center found a cervical spine fracture incidence of nearly 5%9. Cervical spine fractures are also uncommon in manual strangulation. However, it is still recommended that precautions be taken to stabilize the cervical spine until such injury can be appropriately excluded.

Fractures of bony and cartilaginous structures in the neck are common, reported in both near-hanging and strangulation victims. Cricoid fractures are touted as the most serious of laryngotracheal injuries; being the only complete ring, fracture of this structure can rapidly lead to complete airway obstruction. Fortunately cricoid injuries are rare. Other, more common injuries are hyoid bone fractures and laryngeal fractures and contusions. These injuries may present with subcutaneous air or bony crepitus over the larynx. Patients may also exhibit dysphonia, aphonia, dyspnea, stridor, hemoptysis, neck tenderness over the larynx, or loss of landmarks of the anterior neck secondary to swelling or overlying hematoma. Pain with movements of the tongue or with swallowing may imply injury to the epiglottis, hyoid bone, or laryngeal cartilage. Injury to any of these structures puts patients at risk for airway obstruction from edema. Obstruction can be delayed, rapid, and life-threatening, making close airway monitoring a must.

Blunt vascular injury is rare but is thought to be one of the most underdiagnosed injuries and may have devastating delayed complications. It has been reported in both near-hanging and strangulation victims. Diagnosis requires a high index of suspicion, as patients are frequently asymptomatic immediately after the injury. Injury is thought to occur from compression of the common carotid artery against the transverse processes of the fourth to sixth vertebrae leading to hemorrhage within the media or intimal disruption. Both thrombosis and thromboembolism can lead to delayed neurologic signs and symptoms.

Imaging
There is inadequate experience or data to recommend an evidence-based approach to imaging in strangulation or near-hanging victims. Imaging should be ordered based on clinical suspicion.

Plain radiographs may show signs suggestive of laryngotracheal injury, such as subcutaneous emphysema, tracheal deviation from edema/hemorrhage, or hyoid bone fracture. Fracture of non-calcified cartilages may not be readily apparent on plain film and further imaging should be pursued if this is suspected. Plain films utility in determining life threats or helping the physician disposition their patient is limited. Patients that require imaging who are stable enough for CT scan or MRI will get little to no benefit from a pre CT/MRI Plain Film. Fiber optic laryngoscopy is useful to evaluate the soft tissues of the oropharynx but tells us little about the deeper soft tissue injuries. This can help us identify patients who may need further imaging or observation. CT is much more sensitive for bony, cartilaginous, and soft tissue injuries, subcutaneous emphysema, edema, and hemorrhage. MRI is the best imaging modality for deep soft tissue injury and edema. It is the best modality for assessing the deep soft tissues, larynx, and vessels; however, it is not as readily available from the ED and its cost and time requirements make it less appealing for routine use.

CT Angiography is considered by most to be the test of choice when evaluating for blunt vascular injury. It boasts sensitivities up to 100% (for clinically significant injuries). Carotid Doppler ultrasound is an alternative method for diagnosis of carotid injury and it has the advantage of being readily available, portable, and does not require radiation or IV contrast. The disadvantage of this method is that ultrasound has a lower resolution than CT and thus, lower sensitivity. Its sensitivity is reported as 80-90%. The most extensive review of imaging modalities for strangulation victims by Stapczynski in 2010 gives recommendations based on clinical scenarios in terms of which type of imaging to pursue.

Overhanging these recommendations is the understanding that “There is not enough experience to present an evidence-based approach for the use of the CTA.” The author then goes on to recommend CTA for patients who remain unconscious after ED arrival or exhibit unilateral neurologic signs9. Several paragraphs later the author discusses MRI stating “There is not enough experience with MRI to present an evidence-based decision tool for its use in strangulation victims.” His recommendation is that MRI be done in patients who are awake but report a loss of consciousness during the strangulation episode or have facial or conjunctival petechiae.

Ultimately it seems as though there are several modalities available to us when evaluating strangled patients. The most severely injured and the least severely injured are the two groups that you can decide imaging most easily. Someone with no signs of trauma and no neurologic symptoms should just require a period of observation, if anything, following initial evaluation. People that remain unconscious or have signs of neurologic injury will need further imaging be it MRI or CTA. People with no neurologic injury but with evidence of trauma and or petechial or subconjunctival hemorrhage seem to merit some sort of imaging although exact recommendations are not available at this time. MRI seems to give the most information regarding the direct injury to the soft tissues and vessels and further information regarding neurologic injury to the central nervous system.

Management and Disposition
As with any ED patient, airway management is the initial priority. The best and safest technique for intubation is controversial but oral intubation, if necessary, is safe in most. Given the potential for delayed and rapid airway obstruction, earlier intubation often leads to easier intubation in this patient population. This should be a consideration if the patient will be leaving the department for imaging studies or prior to transfer to another facility if necessary.

In patients not requiring emergent or early intubation, serial exams are crucial. It is important to re-evaluate frequently for evidence of progressive airway or vascular compromise, such as dyspnea, dysphonia, stridor, drooling, bruits, and focal neurologic deficits. Clinically these patients can be divided into 3 main groups. First you have the patients who show little to no evidence of trauma and or vascular congestion, who are and have remained conscious and have no neurologic deficits. Second, there are the patients that had an episode of unconsciousness or continue to be unconscious requiring intubation or have neurologic deficits. The third and the final group include patients with voice changes, petechial and or evidence of trauma from the strangulation. The first group can be assessed and discharged without imaging or observation period. Recommendations for group two the most severely injured are ABCD stabilization and admission to the appropriate level of care. Group 3 will be the group that requires that the provider decide imaging (CTA vs. MRI vs. observation), and if observation is decided then 12 hour vs. 24 hour. 2,4,5

Case Conclusion
Our patient underwent a 6-hour observation period and was deemed medically stable for a psychiatric evaluation. There was no issue with his airway, vascular or neurologic systems and the patient was cleared by Psychiatry the next day and discharged home.

References

1. United States Census Bureau; Statistical Abstract of the United States; 2012.

2. Vander Krol L, Wolfe R. The emergency department management of near-hanging victims. J Emerg Med 1994;12:285-92.

3. Taliaferro E, Hawley D, McClane G, Strack G. “Strangulation in Intimate Partner Violence”. Intimate Partner Violence: A Health-Based Perspective. Chapter 16:217-35.

4. Schaider J, Bailitz J. Neck Trauma: Don’t Put Your Neck On The Line. Emergency Medicine Practice. Volume 5, Number 7. July 2003.

5. Stapczynski, J. Stephan. “Strangulation Injuries.” Emergency Medicine Reports. 2 Aug 2010.

6. Iserson KV. Strangulation: A review of ligature, manual, and postural neck compression injuries. Ann Emerg Med 1984;13:179-85.

7. Vilke G, Chan T. Evaluation and Management for carotid dissection in patients presenting after choking or strangulation. J Emerg Med 2011;40:355-58.

8. Clarot F, Vaz E, Papin F, Proust B. Fatal and non-fatal bilateral delayed carotid artery dissection after manual strangulation. Forensic Sci Int 2005;149:143-50.

9. Salim A, Martin M, Sangthong B, Brown C, Rhee P, Demetriades D. Near-hanging injuries: A 10-year experience. Int J Care Injured 2006;37:435-39.

10. Rosen’s Emergency Medicine.

Dr. Ashley Menne is a 4th year EM Resident at the Denver Health Emergency Medicine Residency Program. Dr. Peter Pryor is an Attending Physician at Denver Health and Assistant Professor of EM at the University of Colorado School of Medicine.