Ligature Strangulation Injury

Ligature strangulation is compression of the neck by a cord, wire, cloth or similar material tightened by a force other than body weight. It can cause airway obstruction, vascular occlusion and hypoxic brain injury, and often indicates assault.

Epidemiology. It is a cause of homicide, and non-fatal cases are often linked to intimate partner violence, sexual assault and self-harm. Many survivors have few visible signs.

Mechanism. Pressure of 2 kg on the jugular veins, 5 kg on the carotid arteries, 15 kg on the trachea and 30 kg on the vertebral arteries occludes the structure. Carotid occlusion causes loss of consciousness within about 10 to 15 seconds, and death follows after several minutes.

Pathophysiology. Venous congestion, then arterial occlusion and hypoxia. Reflex bradycardia or arrhythmia from carotid sinus stimulation, laryngeal injury with delayed oedema, pulmonary oedema and carotid or vertebral dissection with delayed stroke.

Presentation includes a horizontal ligature mark around the neck (may be faint), bruising, petechiae of the face, conjunctivae and mucosa, voice change, hoarseness, pain on swallowing, cough, dyspnoea, neck swelling, subcutaneous emphysema, loss of consciousness, incontinence, headache, and neurological symptoms. Fingernail marks on the neck suggest a victim's attempt to remove the ligature. Look for defensive injuries.

Red flags.

• Stridor, voice change, neck swelling or subcutaneous emphysema.
• Loss of consciousness, incontinence, focal deficit or visual change.
• Pregnancy, or a ligature mark with petechiae.

Document injuries with photographs and body maps, with consent where possible. CT angiography of the neck is advised for any history of loss of consciousness, neck marks with symptoms, voice change, dysphagia, respiratory symptoms or neurological signs. CT of the larynx for suspected fracture, and flexible laryngoscopy if voice change or stridor. MRI brain if neurological signs. ECG, troponin and chest radiograph. Pregnancy test.

Differential diagnosis. Hanging, manual strangulation, accidental ligature (clothing, scarf), intoxication, seizure and primary cardiac arrest.

Airway. Assess and secure the airway early, since oedema progresses over hours. Intubate for stridor, expanding swelling or respiratory failure, with an awake approach and a difficult airway plan. Protect the cervical spine.

Breathing and circulation. Oxygen, ventilatory support and usual cardiac arrest care. Targeted temperature management after cardiac arrest.

Vascular injury. Antithrombotic treatment for dissection, directed by vascular and stroke specialists: aspirin 300 mg then 75 to 100 mg daily, or heparin, after intracranial bleeding is excluded.

Observation. Observe for at least 24 hours when there are any airway, vascular or neurological symptoms, because deterioration is delayed. Discharge only with clear advice to return, and not alone.

Forensic and safeguarding care. Preserve the ligature and clothing as evidence, keep a continuous record of custody, take photographs and notes in the patient's words, and offer a forensic and sexual assault examination with consent. Assess the risk of further harm, involve social work, police and domestic abuse services as law and consent allow, and safeguard children.

Monitoring. Airway, swallowing, voice, neurological observations and vital signs.

Referral and escalation. ENT, intensive care, neurology and vascular teams, forensic medicine, and specialist support services.

Special groups. In pregnancy, check foetal wellbeing and consider placental injury. In children, report to child protection services.