Complications of Strangulation
Hanging may occur in a complete or incomplete fashion. Complete hanging is defined as the victim's body being completely suspended and the feet are not touching the ground. When their feet are touching the ground, this is referred to as incomplete hanging. If hanging victims are dropped from a height greater than his or her height, forceful distraction of the head from the neck and the body cause unstable upper cervical spine injuries, transection of the spinal cord, and death. Victims who drop from a height less then their own height or via incomplete hanging typically experience constriction of vital neck structures causing cerebral venous congestion leading to cerebral ischemia and loss of consciousness. Eventually, loss of postural tone occurs and exacerbates constriction of vital structures leading to arterial cerebral blood flow and asphyxiation. When the ligature knot is tied at the midline behind the occiput, that also precludes to arterial occlusion. It is also possible for cardiac arrest to occur during a hanging due to persistent carotid sinus stimulation leading to increased vagal tone (especially in the elderly). It takes approximately 4 minutes of compression of vascular structures to cause irreversible neurologic damage or death; hence attackers let go of their victims before death actually occurs and hanging victims succumb to complications other than asphyxiation.
Victims of incomplete hanging have potential for laryngeal injuries including fractures of the thyroid cartilage (50%), hyoid bones (20%), larynx, or cricoid cartilage. Although rare, fractures of the cricoid cartilage (which usual occurs during manual strangulation) can lead to death through acute airway obstruction and are the most serious laryngeal injuries.
It is important to be aware of the pulmonary sequela including pulmonary edema, pneumonia, and ARDS, which are more commonly seen in incomplete hanging cases. Neurogenic pulmonary edema occurs as a result of central mediated sympathetic discharge and is most commonly associated with serious brain injury. Post-obstructive pulmonary edema develops after the obstruction and high negative intrapleural pressure associated with hanging is relieved (victims taken down) and can rapidly progress to ARDS.
Evaluation and Management
Evaluating stable patients after strangulation injuries is a challenge because they may have non-specific symptoms and occult injuries making the diagnosis difficult. Serial airway, neurologic, and vascular exams are crucial to identify potential decompensation. Survivors who present to the ED may have overt signs of strangulation such as abrasions, ligature marks, or petechial hemorrhage of the skin, mucosa and conjunctiva above the area of compression. Evaluate patients for signs airway injuries and obstruction such as dysphonia, aphonia, dyspnea, stridor, hemoptysis, subcutaneous emphysema and crepitus, tenderness or hematoma overlying the larynx. Pain with tongue movement suggests injury to the epiglottis, hyoid bone, or laryngeal cartilage.
Imaging considerations in strangulated and hanging victims should probably include radiographs of the chest and neck to identify pulmonary infiltrates or edema, subcutaneous emphysema and edema, fractured cartilaginous laryngeal structures. Current literature does not provide guidelines on the use of computed tomography (CT), hence liberal use of CT is common practice. In appropriate cases, a head CT and CT-angiogram of the neck should be obtained. A neck CT provides is more sensitive than radiographs for detecting potential laryngotracheal injuries and assessing airway diameter, presence of hematomas, or cricothyroid or cricoarytenoid joint dislocations.
Management should address potential airway compromises, dysrhythmias, cervical spine injuries, neurogenic pulmonary edema, and cerebral edema. Routine airway management with cervical spine immobilization when there are potential cervical spine injuries is advised. The comatose or altered patient should be presumed to have cerebral edema and elevated intracranial pressure until proven otherwise and managed accordingly. Be aware that baseline neurologic status does not predict neurologic outcome. Patients with pulmonary edema respond well to positive end-expiratory pressure (PEEP). Vascular injuries from strangulation and hanging are very rare, but carotid dissection or thrombus formation causing partial or complete vascular occlusion and embolism have been reported. Consider vascular imaging studies in those with unexplained neurologic deficits. Cervical spine or spinal cord injuries from incomplete hangings are also uncommon so routine imaging in such cases is not necessary.
Disposition
In appropriate cases, consider admission for observation of delayed sequela such as a threatened airway from traumatic edema of the larynx and supraglottic tissue or delated mortality from neurogenic pulmonary edema and aspiration pneumonia. Psychiatric and emotional support should be provided for survivors. Over time patients and their family should be made aware of long term neuropsychiatric complications (i.e. PTSD, psychosis, amnesia, dementia) that may arise.
References:
- Iserson KV: Strangulation: a review of ligature, manual, and postural neck compression injuries. Ann Emerg Med 13: 179, 1984.Fowler D.R. (2011).
- Chapter e263.2. Forensics. In Tintinalli J.E., Stapczynski J, Ma O, Cline D.M., Cydulka R.K., Meckler G.D., T (Eds), Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e. Retrieved June 12, 2015 fromhttp://accessmedicine.mhmedical.com.ezproxy.rush.edu/content.aspx?bookid=348&Sectionid=403817
by Dr. Marcus Emebo
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