Blast injuries to the ear: an historical and literary review

Otorrinolaringología

The terrorist attack on 11 March caused a high percentage of patients with ear injuries. Shock waves provoke alterations to the external ear as well as to the middle and inner ear. The most frequent lesion is tympanic membrane perforation. Initial evaluation with otoscopy, acoumetry, tonal audiometry and vestibular examination was performed and was repeated after 2 and 3 months. In most patients there was a correlation between the grade of middle ear lesion and auditory damage. In most patients with tympanic rupture, the perforation was total or subtotal. Spontaneous closure can occur in some patients but is usually related to the size of the initial lesion. Thus in tympanic perforations of more than 50%, spontaneous closure is unlikely.

Spontaneous healing of traumatic tympanic membrane perforations in man: a century of experience

Widespread controversy exists concerning the treatment of traumatic tympanic membrane perforations. To elucidate the issue, a reference value for the rate of spontaneous tympanic membrane closure in man, to which the healing rates following different techniques of early surgical repair should be compared, was established on the basis of a review of more than 500 texts covering a century's literature on the traumatically perforated tympanic membrane. The spontaneous healing rate appeared to be close to 80 (78.7 per cent) in 760 evaluable cases of traumatic tympanic membrane perforations of all sorts diagnosed within 14 days post injury. A relative, causal-related variation of spontaneous healing could be demonstrated, and a pathogenetic classification of direct traumatic tympanic membrane perforations into ruptures induced by air-pressure changes, heat or corrosives, solids, and water pressures, is of proved clinical value and may have medico-legal validity. There is an obvious need for clinically controlled studies on the spontaneous healing of all kinds of traumatic perforations of the tympanic membrane in humans, and important elements in the design of future studies are advocated.

Middle ear injury in animals exposed to complex blast waves inside an armored vehicle

With greater reliance on armored vehicles of improved survivability, questions have arisen about the likelihood of the wounding of vehicle occupants from blast waves alone. In this study, we placed anesthetized animals (sheep or pigs) inside lightly armored vehicles and exposed them to the blast waves generated by one of three sizes of shaped-charge munitions. Sixty-seven animals were exposed and 15 served as controls. No difference was noted between exposed and control groups for blast injury to the respiratory or gastrointestinal tracts. In contrast, middle ear damage was observed exclusively in animals exposed to blast and was correlated strongly with the peak pressure. The ear is the organ most sensitive to blast damage, and if protectors are not used, military physicians can expect to see a high incidence of middle ear injury in modern combat. The operational consequences of such an injury are not known.

Primary blast injury after a bomb explosion in a civilian bus

A 6-kg explosive charge detonated under a seat in the center of a crowded city bus in Jerusalem, killing three passengers immediately. Of the 55 survivors, all of whom were transferred to two major medical centers, 29 were hospitalized. Among those admitted, a high rate of primary blast injuries was found, including perforated ear drums (76%), blast lung (38%), and abdominal blast injuries (14%). Two of the latter patients suffered bowel perforations, which were diagnosed with considerable delay. Eight patients (31%) had sustained life-threatening trauma, consisting of a combination of primary, secondary, and tertiary blast injuries. The overall mortality rate was 10.3%. The large number of primary blast injuries, including the unexpected finding of bowel perforations, is explained by the high amplitude of the air pressure wave (3.8-5.2 atm) and its relatively long duration (2-3 msec) resulting from the detonation of the high-energy explosive charge in the small, enclosed space of the bus. Besides the usual wounds sustained by victims of an explosion that occurs in a confined space, the possibility of primary blast injury to the abdomen and to the lungs should be taken into account by the treating surgeon.

The ENT problems following the Birmingham bombings

The ENT problems following the Birmingham bombings of 1974 are presented. It is during the positive phase of bomb blast that the tympanic membrane ruptures. Spalling is a likely explanation for the mechanism of rupture of the tympanic membrane specially in large perforations. Tympanic membrane defects involving 80 per cent of the surface area of the drumhead or more persisted, whereas those involving less than 80 per cent healed with conservative treatment. The majority of perforations (81.4 per cent) healed spontaneously, with a three-layered membrane. A month should be allowed for the healing of every 10 per cent loss of the surface area of the drumhead. During surgical repair of persistent perforations, the malleus handle was found to be on a deeper plain than the long process of the incus. Tympanic membrane perforations did not protect the inner ear, the sensorineural deafness producing either a high tone or a flat loss. One in four of the victims seen in the hospital complained of deafness. A patient who suffered blast injuries to the lung also developed cord palsy.