Extreme implosive forces1820 Certain types of acoustic trauma may also cause PLFs We have confirmed reports of PLFs in patients exposed to explosions or to sudden or catastrophically loud sound21

With the advent of stapedectomy, PLFs were implicated as a complication of stapes surgical procedures,22-24 particularly if Gelfoam was used as the graft or if polyethylene tubing was used as a prosthesis.25,26

In 1971, Goodhill27 advanced the theory of implosive and explosive mechanisms for traumatic PLFs. According to Goodhill, an explosive PLF occurs when a sudden increase in the cerebrospinal fluid (CSF) pressure that ruptures the oval or round window due to increased intracranial pressure is transmitted to the perilymphatic fluid space. An implosive event occurs when sufficient external (ambient) pressures were applied to the tympanic membrane or entered the middle ear through the eustachian tube, driving the stapes into the inner ear and causing rupture of the oval or round window, or both.

G.A. Fee, an astute Canadian otolaryngologist,28 was among the first to identify trauma as a cause of PLFs5,29-35 in patients suspected of having Meniere's disease. The most likely mechanism of PLFs after blunt body or head trauma is a transient dramatic increase in intracranial pressure, as proposed by Goodhill's explosive theory.27 The head trauma need not be severe. Whiplash injury has been linked to PLFs.36 Goodhill's explanations probably account for PLFs occurring in association with whiplash trauma to the neck, and without direct head blow.36

A more recent example of implosive PLF formation is airbag deployment trauma. According to Ferber-Viart et al.,37 airbags may reach peak volume in 50 ms after impact, inflating at a speed of 156 mph, and with an opening force equivalent to a shotgun blast. Traumatic injury to head, neck, upper body, and face in association with airbag deployment has been well documented.38-40 These reports suggest that PLFs from airbag injury are likely to increase.

The patient with spontaneous or idiopathic PLF exhibits signs, symptoms, and findings fully consistent with PLFs but that lack correlation to a specific cause.41-45 In reality, spontaneous PLFs probably do not exist per se but are more likely a reflection of the inability to correctly identify a causative event.

Anatomic variants have been associated with PLFs,46,47 including patent fissula ante fenestrae,1,2,48,49 large patent cochlear aqueducts,50,51 the Mondini deformity,52,53 and oval window microfissures.2,54,55 In some cases, anatomic variants may show familial tendency.56 Congenital PLFs have been described by many clinicians;47,56-59 in some cases, congenital PLFs appear to have anatomic and/or familial links.

Within the modern otologic community, great diversity exists with regard to the identification and management of PLFs. A detailed review is beyond the scope of this chapter. The following discussion summarizes our methods and approaches in dealing with some of the purported controversies associated with the care of the PLF patient.

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