Benign paroxysmal positional nystagmus in hospitalized subjects receiving ototoxic medications

Vestibulotoxicity Associated With Platinum-Based Chemotherapy in Survivors of Cancer: A Scoping Review

Background: Cochleotoxicity following the treatment with platinum-based chemotherapy is well documented. The potential for vestibulotoxicity is still unclear. This scoping review examined the extent of current research literature, summarized research findings and identified research gaps regarding vestibular-related adverse effects associated with platinum-based chemotherapy in survivors of cancer.

Methods: Inclusion criteria followed the PICO principles: Participants, adult, and pediatric cancer patients of any cancer type; Intervention, platinum-based chemotherapy (such as cisplatin, carboplatin, and oxaliplatin); Control, none or any; Outcomes, vestibular-related adverse effects. English language articles published since 1978 were retrieved. Seventy-five eligible studies were identified from a systematic literature search, and relevant data were charted, collated, and summarized.

Results: Testing for vestibulotoxicity predominately featured functional evaluation of the horizontal semicircular canal using the caloric and rotational tests. The rate of abnormal vestibular function test results after chemotherapy administration varied from 0 to 50%. The results of objective testing did not always correspond to patient symptoms. There is tentative support for patients with pre-existing loss of vestibular function to be more likely to experience vestibular toxicity after dosing with cisplatin.

Conclusions: A number of studies reported significant evidence of vestibular toxicities associated with platinum-based chemotherapy, especially cisplatin. This scoping review emphasizes that vestibular toxicity needs more attention and comprehensive evaluation. Specifically, studies that analyse cumulative dose of platinum-based chemotherapy, affected sites of lesion in vestibular end organs, and the correlation and temporal patterns of cochlear and vestibular toxicity are needed.

Our experience with 500 patients with benign paroxysmal positional vertigo: Reexploring aetiology and reevaluating MRI investigation

OBJECTIVE

To explore the aetiology of and to evaluate the importance of MRI investigation on the posterior semicircular canal benign paroxysmal positional vertigo in an Irish population.

METHODS

A retrospective observational study of 500 patients with posterior semicircular canal benign paroxysmal positional vertigo, diagnosed and treated by the senior author over a 10-year period. Most patients underwent an MRI brain and inner ear, following the same scan protocol. This included T1 weighted sagittal IR-FSPGR volume, axial T2 weighted, gradient echo T2 weighted and FLAIR sequences plus time of flight cerebral angiography.

RESULTS

The average age of presentation was 56 years; with the overall female to male ratio was 1.6:1, which was largely the net results of 2 age groups. Over 30% of our patients recalled distinct aetiological triggers, of which the top 3 were trauma, infection, and surgery. These accounted for 16%, 6%, and 5%, respectively. More than 25% of the patients were discovered to have abnormal intracranial findings on MRI. The 2 most common non-infarct incidental findings were neoplasia and vascular abnormalities. Although fewer than 20 patients had acute intracranial haemorrhage or malignant tumours, most of them were urgently referred to neurosurgeon due to the life-threatening nature of the condition. One round of particle repositioning manoeuver was successful in treating 84% of the patients, and the 2-year recurrence rate was only 2.2%.

CONCLUSION

The diagnosis of posterior semicircular canal benign paroxysmal positional vertigo is thought to be relatively easy to make, and the treatment is highly effective. Clinicians should be fully aware of and prepared for the diverse aetiology, and thus have no hesitation in requesting MRI scan as an important investigation.

[Otoconia : Current aspects of research]

Otoconia are calcite-based nanocomposites containing >90 % calcite and <10 % organic material. The mean size is approximately 10 µm. The external structure of all otoconia in the utricle and saccule is similar, with a cylindrical bulbous body with a slightly hexagonal contour. The internal structure consists of a composite with varying volume thickness, dense branching structures (branches) and less dense surrounding areas (bellies). Intact otoconia can be clearly identified only by scanning electron microscopy. In the case of morphological changes (e.g. due to "degeneration") the origin of even very small particles of otoconia can be assigned using physical and chemical analytical methods. The inorganic component of otoconia (calcite) is extremely sensitive to chemical influences, which leads to morphological alterations. A "degeneration" of otoconia can be objectively accomplished in vitro by alterations in pH, electrolyte imbalance and by the influence of complex formation. These three main processes then lead to irreversible morphological alterations. Artificial (biomimetic) otoconia serve as a suitable model system for detailed investigation of growth and degenerative processes.

[Current aspects of ototoxicity. Ototoxic substances and their effects]

Ototoxicity describes reversible or irreversible disorders of inner ear functions due to the influence of chemical, biological, or physical substances. Ototoxicity should be kept in mind during differential diagnosis of hearing loss, tinnitus, dizziness, and vertigo. In clinical practice, drug-induced ototoxic effects play a major role. The otorhinolaryngologist should also be involved in interdisciplinary cooperation, e.g., during treatment with antineoplastic chemotherapeutic agents with potential ototoxic side effects. In clinical practice, multimedication and interactions between different agents can complicate precise correlation in individual cases. Recent studies also show that noncellular components, such as otoconia, are extremely sensitive to chemical attacks.

Principles of calcite dissolution in human and artificial otoconia

Human otoconia provide mechanical stimuli to deflect hair cells of the vestibular sensory epithelium for purposes of detecting linear acceleration and head tilts. During lifetime, the volume and number of otoconia are gradually reduced. In a process of degeneration morphological changes occur. Structural changes in human otoconia are assumed to cause vertigo and balance disorders such as benign paroxysmal positional vertigo (BPPV). The aim of this study was to investigate the main principles of morphological changes in human otoconia in dissolution experiments by exposure to hydrochloric acid, EDTA, demineralized water and completely purified water respectively. For comparison reasons artificial (biomimetic) otoconia (calcite gelatin nanocomposits) and natural calcite were used. Morphological changes were detected in time steps by the use of environmental scanning electron microscopy (ESEM). Under in vitro conditions three main dissolution mechanisms were identified as causing characteristic morphological changes of the specimen under consideration: pH drops in the acidic range, complex formation with calcium ions and changes of ion concentrations in the vicinity of otoconia. Shifts in pH cause a more uniform reduction of otoconia size (isotropic dissolution) whereas complexation reactions and changes of the ionic concentrations within the surrounding medium bring about preferred attacks at specific areas (anisotropic dissolution) of human and artificial otoconia. Owing to successive reduction of material, all the dissolution mechanisms finally produce fragments and remnants of otoconia. It can be assumed that the organic component of otoconia is not significantly attacked under the given conditions. Artificial otoconia serve as a suitable model system mimicking chemical attacks on biogenic specimens. The underlying principles of calcite dissolution under in vitro conditions may play a role in otoconia degeneration processes such as BPPV.

Is routine audiometric evaluation necessary in gynaecologic tumour patients undergoing chemotherapy?

BACKGROUND

Our objective was to assess the auditory function of gynaecological tumour patients who had received cytotoxic agents and to determine their associated risk of ototoxicity.

PATIENTS AND METHODS

87 patients who had undergone chemotherapy for gynaecological malignancies were investigated. Of these patients, 79% had breast cancer, and 14% ovarian cancer. All of the patients had a subjective assessment of their hearing function on a visual analogue scale. Audiometric tests were performed before and at 9 weeks, 18 weeks and 3 months after completion of chemotherapy.

RESULTS

The age of the patients ranged from 32 to 71 years (mean age of 53.5 ± 10.5 years). The average subjective rating of the patients' hearing function was 83.0 ± 17.2 before and 84.8 ± 16.9 3 months after completion of chemotherapy. No significant audiometric change at either the speech hearing frequency range (0.5-2 KHz) or high frequencies was observed in the patients after chemotherapy. There was also no significant difference in the hearing threshold of the patients who had received platinum analogue-based chemotherapy compared to non-platinum analogue-based chemotherapy.

CONCLUSION

Hearing loss is uncommon in patients treated with the typical gynaecological chemotherapy protocols. Hence, routine audiometric testing in these patients is not necessary.

Self-treatment of benign paroxysmal positional vertigo with DizzyFix, a new dynamic visual device

Benign paroxysmal positional vertigo is one of the most common disorders of the vestibular system. It is characterized by episodes of recurrent vertigo triggered by head movements or position changes associated with nystagmus. There is scientific evidence that in the majority of cases this condition responds well to the particle repositioning maneuver (PRM) correctly performed by the physician. However, the PRM needs to be repeated in approximately 30% of the cases. Although the maneuver is simple, patients often find it difficult to perform correctly as self-treatment, with the result that it fails to bring about an improvement in the symptoms. DizzyFix (Clearwater Clinical Limited, Canada) is the name given to a new dynamic visual device designed to provide a visual representation of the PRM based on the canalith theory. The DizzyFiX consists of a specially curved acrylic tube containing a nontoxic viscous fluid and a bead, the purpose of which is to help the patient and the inexperienced physician to perform the PRM correctly. A randomized clinical trial has shown that it reliably enables the maneuver to be performed correctly, and a study investigating the effectiveness of patient self-treatment of benign paroxysmal positional vertigo with the device in comparison with standard office treatment revealed both techniques to be equally effective. The device has now been approved by the US FDA.