Viral and bacterial infections, as well as drug and chemical poisoning, can induce vertigo. The manifestations vary depending on the timing and severity of cochlear and vestibular damage, with some cases primarily presenting vertigo, while others mainly exhibit tinnitus and deafness. Currently, the most common cause is drug poisoning, such as antibiotics, diuretics, anticancer drugs, and heavy metals like lead and mercury. Among these, aminoglycoside antibiotics are the most frequently implicated, including streptomycin, neomycin, kanamycin, and gentamicin. Streptomycin sulfate poisoning is the most severe, accounting for approximately 12% of vestibular damage cases in China. These drugs interfere with and disrupt cellular protein synthesis, damaging the vestibular end organs and nuclei, and may even affect the cerebellum and brainstem. Therefore, the severity of poisoning is not directly proportional to the dosage administered and may be related to individual susceptibility and renal function. Poisoning can be classified into acute and chronic types. Acute poisoning manifests symptoms on the day of medication or within a few days. Most cases are chronic poisoning, typically occurring 2–4 weeks after drug administration. Even after discontinuation, symptoms may progressively worsen, peaking within a few days. If the drug is continued, symptoms may develop more rapidly. This phase can persist for several years.

bubble_chart Clinical Manifestations

Symptoms in children are mild and few, while in adults they are more severe and common. Patients often complain of tinnitus, dizziness, nausea, and vomiting. If the vestibular center is affected, blurred vision or floaters may occur, with severe cases experiencing unclear vision during head movement that improves after cessation. Patients often walk with a stiff head position and move straight forward, known as visual recognition disturbance vertigo (Dandy's syndrome). If the patient is insensitive to medication, symptoms may only appear after high doses, but these are not vertigo but rather a drunken-like unsteadiness. In cases of chronic poisoning, due to good individual compensatory function, even if bilateral vestibular function is completely lost, the patient may remain unaware until vestibular function tests reveal severe impairment. Bilateral damage is often asymmetrical, sometimes severe on one side and normal on the other, with caloric tests possibly showing directional preponderance. Cochlear vestibular and hearing impairments are not directly linked; sometimes severe vestibular damage coexists with normal hearing. Generally, varying degrees of sensorineural deafness are present.

There is a clear history of drug poisoning disease, and the diagnosis is generally easy.

bubble_chart Treatment Measures

Clinically, prevention should be prioritized, avoiding or minimizing the use of toxic drugs whenever possible. When their use is necessary, weekly cochlear vestibular function tests should be conducted for monitoring. If functional impairment is detected, the medication should be discontinued promptly, and treatment with neurotrophic drugs, vasodilators, high doses of vitamins A and B, and similar medications should be initiated. Sedatives are generally not recommended. Early administration of BAL is more effective.