Chemically Induced or Drug Induced Tinnitus

F or approaching the truth about the clinical phenomenon of tinnitus from more and more possible aspects, it is important in the sense of the old Aristotelean systematics of scientific thinking to choose various and alternating directions for regarding the phenomenon. Therefore, today I am also choosing a biochemical angle of view. Our model of good and bad hearing, ear noise or tinnitus , is primarily demonstrated in the dimension of physics and modern data technology. Hearing is based on the transmission of physical sounds from the surrounding world by resonance in space to the outer ear; the physical amplifier of the middle ear; and finally by digital data transmission from the cochlea via the hearing pathways to the temporal lobe of the brain. However, the human spirit, with all its sensory capacities, does not reside in a technically isolated house nor in a computer, but in a chemically constructed and biologically functioning human body. Many dysfunctions of the central nervous system, including the symptom of tinnitus can be elicited on a biochemical basis. For example, the toxic effect(s) of solvents or the so-called untoward side effects of various drug therapies. From an ecological as well as as neurotologic standpoint, particularly in the past 30 years, society has become increasingly aware of the dangers to human neurosensory function(s) secondary to special industrial chemicals called solvents. A clinical syndrome has been identified, related to this danger, called CHRONIC TOXIC ENCEPHALOPATHY (CTE) (Odkvist et aI., 1988). The onset of symptoms are gradual and increase in intensity and multiplicity of central nervous system involvement following an initial and subsequent chronic exposure of the patient to the inhalation from the air of vapors of the solvent(s), e.g., Trichlorethylene, Tetrachlorethane, and Hexane (Gasoline), Cyclohexane, Tolluol , Styrene, Methyl-n-butyl-ketone, Methylchloride, Dichlormethane, Trichlorethylene, Perch lor-ethylene, Lindan, etc. The CTE syndrome has been identified in laborers, technicians , painters as well as others who work and live in a polluted environment. The predominant complaints are disturbances in concentration, memory, cognition, headache, drowsiness, malaise, and balance complaints described as unsteadiness and dizziness. Significant accompanying complaints include hearing disorders and tinnitus. Many patients complain of reduced hearing and understanding of speech. Frequent auditory complaints include a high pitched noise and a sensation of ear blockage. Diagnosis is elusive, but is eventually established. The neurotoxic complications are increased in number and intensity when solvents are multiple in number and are released in combination into the environment. CTE is a chronic progressive disease. Recently, a male patient, age 58, was seen in consultation for severe tinnitus. A prior diagnosis of CTE had been established 26 years ago, secondary to toxic inhalation of trichlorethylene vapors. Tinnitus was reported to have been the initial symptom. The patient discovered the beneficial effect of acoustical masking by placing the noise from a toy train close to the involved ear. It provided temporary relief from the constant and irritating tinnitus noise. Today he reports tinnitus control , i.e., relief with a tinnitus masker. The complaint of ear pressure was eliminated following removal of the patient from the toxic environment. However, the high pitch tinnitus persists. Neurotologic evaluation revealed a bilateral sensorineural hearing loss, primarily cochlear in location; and abnormalities in the early and late brain stem potentials. Vestibular testing with polygraphic electronystagmography (ENG) and cranio-corpo-graphy (CCG) recordings revealed multiple abnormalities compatible with central neurotological disturbances. The public and professional communities should become alert to CTE. Such an awareness will result in its early diagnosis and treatment; and contribute to an increase in our understanding of environmental hazards to public health and concept of tinnitus. Specifically, the concept and diagnosis of CTE should be expanded to include both the physical and chemical worlds for the evaluation and treatment of the symptom of tinnitus. It is well known among the lay public and medical! audiological professional communities that tinnitus may be elicited by a toxic drug overdose, e.g., Quinine and Aspirin. Many medical treatments elicit a chemically induced tinnitus, i.e., iatrogenic. From a medical perspective, the possibility of a toxic effect of a drug prescribed for its pharmacologic and beneficial effect can occur. Classification of drug pharmaceuticals are primarily based on their principle actions. However, it is clear that