Neck Holds

Pressure on and around the neck is well-known to be a potentially lethal action (14). Death can be caused after compression of the neck by any one of four mechanisms or by any combination of two or more of the following:

• Airway obstruction by direct compression of the larynx or trachea or by the pressure on the neck raising the larynx upward and causing the superior aspect of the pharynx to be occluded by the tongue base. This can be achieved by pressure of a forearm across the front of the neck, sometimes called the "choke hold."

• Occlusion of the veins in the neck. The low pressure in the venous system and the thin yielding nature of the vein walls make venous occlusion more easily achieved than arterial occlusion; however, the large reserve capacity of the venous system makes it unlikely that rapid death would result even if complete occlusion was achieved, unless some other factor supervened.

• Compression or occlusion of the carotid arteries. This is harder to achieve than venous occlusion because of the higher pressure in the arterial system and the thickness of the arterial walls; however, the effects of occlusion will become apparent much quicker. Saukko and Knight (14) record that occlusion of the carotid circulation for 4 min or more may result in brain damage, and Reay et al. (15) demonstrated significant changes in blood flow in the face of five individuals who were subjected to compression of the carotid arteries by the application of a "sleeper hold" in experimental conditions. A sleeper hold is applied when the upper arm compresses one side of the neck and the forearm the other and the larynx rests in the "V" formed by the elbow.

• The fourth mechanism by which death can occur during pressure to the neck results from stimulation of the vagus nerve by direct pressure in its course down the neck or as a result of stimulation of the carotid sinus. Vagal stimulation results in bradycardia, which may progress to asystole or, in some cases, immediate asystole.

Mercy et al. (16) reviewed 20 deaths where neck holds had been applied and concluded that in 19 of these cases, the application of the neck hold was associated with the death. Conversely, Kowai (17) concluded that the use of the choke hold could take between 10 and 20 s to cause unconsciousness, and, therefore, it was safe. Clearly, they did not experience the vagal effects of this hold in their experiments.

Neck holds are commonly used in many forms of wrestling or martial arts, and in these situations, they are seldom associated with fatalities, possibly because of the ability of the person held to indicate his or her willingness to submit to a referee and so cause the hold to be released. No such authority is present during a restraint by police; perhaps this is why fatalities are recorded in this situation. In the United Kingdom, the use of neck holds by police during restraint is specifically prohibited and officers are warned during their training of the potentially fatal effects of applying any pressure to the neck. However, in the United States, neck holds are an approved method of restraint.

The pathological examination of deaths associated with compression of the neck requires a detailed and careful dissection of the neck structures (18). The finding of injuries to the muscular, cartilaginous, vascular, or neural components of the neck must be interpreted in the light of the restraint events, the actions of the restrainers, and the subsequent resuscitation, if any. Pressure on the neck to maintain an airway after cardiac or respiratory arrest may result in bruising, which could be confused with pressure before or, indeed, causing that arrest. Therapeutic insertion of cannulae during active resuscitation by paramedics or in the hospital commonly leads to marked hemorrhage in the neck that, although it is unlikely to be confused with bruising caused by a neck hold, may mask any bruising that was present.

Pressure on the neck is not, of course, the only mechanism whereby an individual may suffer anoxia or asphyxiation. Any action that partially or completely occludes the mouth and/or the nose will result in difficulty in breathing and may result in asphyxiation. The features of these other causes of asphyxiation, traumatic or restraint asphyxia, are discussed in Subheading 11.

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