**2. Methodology**

164 Hearing Loss

Caustic injuries to the tympanic membrane can cause its perforation. With alkaline agents, the tympanic membrane is damaged by liquefaction necrosis, that is, the alkaline caustic penetrates the tympanic membrane, causing occlusion of the vasculature that may extend

As a result, the size of the perforation may not be fully appreciated until all of the inflammation is resolved. Furthermore, after caustic injuries, other middle ear pathologies observed include an extensive granulation reaction with scarification, ossicular fixation, chronic infection of the middle ear mucosa, canal blunting where the raw surfaces that surround the canal form a cicatrix, leading to narrowing of the ear canal and loss of the vibratory surface of the tympanic membrane. Other complications are chronic myringitis on the surface of the tympanic membrane, creating a raw weeping surface with granulation on the surface of the drumhead. Treatment involved the use of systemic antibiotics, steroidbased topical ear drops for aural dressing, audiologic assessment and a complete neurotologic evaluation to determine the extent of injury. When the ear has stabilized, and preferably when drainage has diminished, the middle ear and tympanic membrane can be

In Nigeria compared to the developed world it is difficult to know the economic impact of this injury both financially and otherwise. It is estimated that the annual cost of dealing with this tragedy is more than \$100 billion in the USA. In a study done by the National Academy on Aging Society (NAAS) in 1999, it was found that the average value for time lost in a conductive injury due to trauma in the workplace costs more than US \$8,000. [NAAS 1999]. However this data are not available for the developing countries. Trauma patients consume more health care resources than heart and cancer patients combined, and whereas mortality from heart disease and cancer is declining, the incidence from trauma is increasing

Blunt trauma to the skull most frequently occurs as the result of the head being thrown against a solid or semisolid object, or an object being thrown directly at the head. Soft tissue injuries of the external auditory canal may occur with blunt trauma, particularly trauma that is glancing in nature, that is, delivered in a sharp angle to the side of the head as opposed to a 90-degree injury. Fractures of the middle ear structures, otic capsule, and structures surrounding the otic capsule may occur from blunt trauma. The most common form of temporal bone fracture, occurring from blunt trauma, is the longitudinal fracture of the temporal bone. It is estimated that 70% to 90% of temporal bone fractures are longitudinal (Cannon and Jahrsdoerfer, 1983; Dolan, 1989; Nelson, 1979). These fractures most commonly result from direct lateral blunt trauma to the skull in the parietal region of the head. In considering the effect of a fracture of the skull and its relationship to the temporal bone, it is helpful to think of the fracture occurring initially in a weaker portion of the calvarium, such as the squamous portion of the temporal bone, and the fracture line extending toward the temporal bone. Recognizing that the otic capsule is extremely dense bone, the fracture will occur around the otic capsule, taking the course of least resistance (Dahiya et al 1999. The course of least resistance usually involves major foramina in the skull base, the most common being that of the carotid artery and the jugular bulb. Fractures are frequently near the roof of the external auditory canal and run parallel along the petrous apex extending anteriorly to the foramen lacerum and the carotid artery. The line may also extend into the

farther than the visible perforation.

reconstructed surgically.

[Boden&Galizzi 1999, Shires GT et al 1994].

temporomandibular joint regions.

This is a retrospective review of 64 patients seen at the Ear, Nose and Throat clinic and the accident and emergency unit of the University of Ilorin Teaching hospital, Ilorin, Nigeria over a ten year period between January 1998 to Dec 2007. The patients had history of bleeding from the ear due to trauma from various causes. Patients with multiple traumas were also included and these had traumatic tympanic membrane perforation as part of the presentation. The data retrieved included the bio-data, the clinical presentation, source of injury, the clinical findings and the outcome of the patients. These were entered into an SPSS version 11.0 computer soft ware and analyzed descriptively.
