Lightning injury of the tympanic membrane

Lightning and the Forensic Pathologist

This paper explores the pathology caused by lightning. It covers the basic physics and mechanisms of injury of lightning strikes followed by a short discussion. The purpose of this paper is to suggest an approach to the investigation and autopsy of a lightning-related death.

Tympanic Membrane Perforation Caused by Thunderbolt Strike

Thunderbolt strike is a life-threatening entity. In the patients presenting with thunderbolt strike, the central nervous system and the cardiovascular system should be primarily evaluated, followed by tympanic membrane lesions. The most important symptom connected with ear is the loss of hearing. In this report, a 43-year-old male patient with unilateral tympanic membrane perforation, tinnitus, and bilateral sensorineural hearing loss caused by thunderbolt strike is presented through a review of the literature.

The Explosive Effects of Lightning: What are the Risks?

The explosive effects of lightning have been known to exist for some time; however the precise risks associated with it have been generally unknown. This curious injury phenomenon has existed historically under many different names in the literature: "lightning's pressure blast wave," "arc blast," "shattering effects of lightning," "pressures developed by arcs," "thunder generation of shock waves," and "the sixth mechanism of lightning injury" are but a few of the many divergent and disparate terminologies used in the past to describe this invisible blast phenomenon. Blunt force trauma injuries and barotrauma injuries are often identified on lightning strike victims. Lightning's pressure blast wave and its associated overpressure does appear to have significant injury implications associated with it. This paper takes an in-depth look at the explosive effects of lightning and the main blast-related pathologies seen on lightning strike victims. Knowledge and insight into this phenomenon may help forensic pathologists and those working in the fields of lightning injury and lightning protection. A general literature search of the medical, the electrical engineering, and the mechanical engineering literature was conducted. By looking exclusively at the pathology of barotrauma in the human body, forensic pathologists may now get a relatively good idea as to the possible overpressures and distances involved with regards to lightning's explosive effects.

Lightning injury in an outdoor swine herd

Three pigs, weighing 63 kg-70 kg each, from a group of 8 pigs in an outdoor pen that was struck by lightning were necropsied. All 3 pigs presented with hind limb paralysis. The only lesions identified were multiple fractures of the last (seventh) lumbar vertebral body and first sacral vertebral segment, with dorsal displacement of the sacrum and transection of the distal spinal cord and spinal nerves. Hemorrhages extended from the fracture sites into muscles immediately surrounding the lumbosacral junction and retroperitoneally into the pelvic cavity. These hemorrhages were not clearly visible until the pelvic region was dissected. Lesions commonly found in human lightning-strike victims were not present in these pigs. Because vertebral fractures may be the only lesions and may be grossly subtle in heavily muscled pigs, careful pelvic and vertebral dissection is recommended in cases of suspected lightning strike and electrocution.

Effect of healed tympanic membrane perforations on umbo velocity in the rat

Heterodyne laser interferometry was used to measure tympanic membrane (TM) velocity at the umbo during acoustic stimulation in 2 groups of rats. The control group had a normal TM, while in the other group the TM was perforated and then allowed to heal for at least 28 days. Umbo velocity functions for constant sound pressure level stimuli were obtained for test tones between 0.3 and 40.0 kHz in each animal. The results revealed that velocity was the same in the control and healed TMs below 3.0 kHz. Above 5.0 kHz, the velocity response in the healed ear was between 3 and 12 dB smaller than in the control ears. Histologic evaluation of the healed perforation revealed a thick fibrous reaction between the epidermal and lamina propria layers. The results indicated that the added mass of the scar tissue changed the middle- and high-frequency TM responses.

Acoustic trauma caused by lightning

Lesions produced by exposure to noise are frequent in everyday life. Injuries may be found in all systems of the human body, from the digestive to the endocrine, from the cardiovascular to the nervous system. Many organs may be damaged, the ear being one of them. It is known that noise produced by factories, airports, musical instruments and even toys can cause auditory loss. Noises in nature can also cause acoustic trauma. This report is the case history of acoustic trauma caused by lightning. The patient was studied with CAT scan, electroencephalogram, and brain mapping, impedance audiometry with tympanogram and acoustic reflex, audiometry and evoked otoacoustics emissions: distortion products and transients.

The effect of tympanic membrane perforation size on umbo velocity in the rat

The tympanic membrane (TM) in adult rats was surgically exposed and laser interferometry was used to measure TM velocity at the umbo for frequencies between 1.0 and 40.0 kHz. Velocity measures were obtained for five conditions: TM intact, and four progressively larger holes cut into the posterior region of the membrane. Photomicrographs of each condition were used to calculate the percentage of pars tensa lost to the perforation. The relation between TM velocity and stimulus sound pressure level (SPL) was also examined for each of the conditions. The results revealed a systematic loss in low-frequency velocity as perforation size increased. These observations were consistent with clinical reports of low-frequency hearing loss in the perforated human TM. The rat appears to be a successful model for studying this form of conductive pathology.