Multiple temporal bone anomalies in isotretinoin syndrome: a temporal bone histopathologic case report

The evaluation of the use of isotretinoin on vestibular system by using vHIT

AIM

The aim of the present study was to evaluate the effect of isotretinoin (ISO) on peripheral vestibular system using vHIT.

MATERIAL AND METHOD

This is a prospective study in which 30 patients administered ISO treatment with the diagnosis of acne vulgaris was evaluated. Following ear nose and throat, examination, audiological and vestibular evaluations were carried out. vHIT tests were conducted before and three months after the use of ISO (0.5-0.75 mg/kg/day). In addition, all participants underwent perceptual vertigo and dizziness tests before and three months after the use of ISO.

RESULTS

In vHIT evaluation of all patients, no overt saccade, covert saccade and spontaneous nystagmus finding was observed. Gain and asymmetry were compared before and after the use of ISO: No significant difference was found between lateral semicircular canal, anterior, and posterior semi-circular and symmetry measurements made before ISO use and those made three months after it (p = 1.00; p = 0.99; p = 0.66). Similarly, there was no significant difference in asymmetry values of vertical semicircular canals measured before ISO and three months after it (p = 0.90; p = 0.76). No statistically significant difference was found in vertigo, nausea and dizziness in terms of responses before and 3 months after ISO use (p = 0.063; p = 0.031; p = 0.063).

CONCLUSION

Although the studies demonstrating the effect of ISO on cochlea and symptoms occurring during treatment such as nausea, vomiting and vertigo suggest that it may exert effects on peripheral vestibular system, the present study indicates that it has no short terms effects on structures in peripheral vestibular system and vestibuloocular reflex pathways.

Development of canal cholesteatoma in a patient with prenatal isotretinoin exposure

PURPOSE

To describe the clinical and radiologic findings in a case of isotretinoin embryopathy-like syndrome and discuss management of hearing loss, congenital external auditory canal (EAC) stenosis, and EAC cholesteatoma.

METHODS

Review of medical, audiological, and radiological records.

RESULTS

An 8 year old female presented with bilateral moderate conductive hearing loss, bilateral microtia, left EAC stenosis, and right EAC atresia, secondary to prenatal isotretinoin exposure. Comorbidities included developmental delay, ventricular septal defect, hypotonia, and retinal maldevelopment. The left EAC was sharply upsloping with a 2mm-diameter meatus. Computed tomography (CT) scan of the temporal bone demonstrated normal middle and inner ears bilaterally; serial CT scans over 6 years demonstrated progressive development of left canal cholesteatoma. Implantation of a right BAHA system was performed, followed by left canalplasty and excision of cholesteatoma with facial nerve monitoring. An endaural incision was utilized to avoid compromising future microtia repair. Postoperative left-sided hearing improved to mild low-frequency conductive hearing loss rising to normal at 2000 Hz and above.

CONCLUSIONS

Despite extensive precautions for its use, isotretinoin remains a cause of major birth defects, including sensorineural, conductive or mixed hearing loss. Congenital EAC stenosis is much less common than congenital atresia or acquired stenosis; optimal surgical approaches vary depending on hearing status and facial nerve anatomy. Close monitoring for development of canal cholesteatoma is necessary.

Rhabdomyomatous hamartomata of the pharyngeal region with bilateral microtia and aural atresia: A new association?

BACKGROUND

Bilateral microtia with aural atresia is rare. Rhabdomyomatous hamartomata containing salivary tissue, situated bilaterally and symmetrically simulating the palatine (faucial) tonsils, has apparently not been reported. We present the combination of these findings in two unrelated patients.

CASES

In the first case, the patient was exposed prenatally to 13-cis-retinoic acid (isotretinoin) and has typical features of this exposure, including bilateral microtia with aural atresia and bilateral 7th nerve palsies. Due to symptoms of obstructive sleep apnea, patient 1 had a "tonsillectomy" and adenoidectomy. Histopathologic studies demonstrated rhabdomyomatous hamartomata containing salivary and striated muscle tissue in place of the palatine tonsils. In the second case, the patient had been prenatally exposed to alcohol, cocaine, and marijuana. He has been noted to have developmental delay and behavioral issues in addition to bilateral microtia with aural atresia. "Tonsillectomy" and adenoidectomy were performed to alleviate chronic upper respiratory infections and snoring. Again, histopathologic studies of the tissue submitted as "tonsil" demonstrated rhabdomyomatous hamartomata containing salivary and muscle tissue. Although an extended banded karyotype and subtelomere panel were normal, a genetic etiology for the second patient's features cannot be excluded.

CONCLUSIONS

We hypothesize that the findings of bilateral microtia with aural atresia and rhabdomyomatous hamartomata containing salivary and muscle tissue in the area of the palatine tonsils may represent a newly recognized association, which may have a teratogenic and/or genetic etiology.

A risk management program aimed at preventing fetal exposure to isotretinoin: retrospective cohort study

BACKGROUND

Preventing fetal exposure to isotretinoin is an important public health goal. Since approval of isotretinoin (1982), the Food and Drug Administration has implemented several unsuccessful risk management programs aimed at preventing fetal exposure. The Kaiser Permanente isotretinoin risk management program included electronic capture of all isotretinoin prescriptions and the documentation of pregnancy testing with each dispense.

OBJECTIVE

Our aim was to analyze the success of Kaiser Permanente's program at improving pregnancy testing rates and reducing fetal exposure.

METHODS

This was a retrospective cohort study.

RESULTS

Pregnancy testing rates improved after implementation of the Kaiser Permanente program. However, the rate of fetal exposure to isotretinoin did not change (0.21% before vs 0.23% after, P = .85). LIMITATIONS/CONCLUSION: In this study, linking a negative pregnancy test to isotretinoin dispensing did not reduce fetal exposures. Patient failure to use two contraceptive methods was the most common reason for fetal exposure. These results have important implications for iPLEDGE, the new isotretinoin risk management program mandated by the Food and Drug Administration.

Temporal bone pathology in fetuses exposed to isotretinoin

Isotretinoin can be teratogenic, affecting many tissues, including the ear. However, there are only two histopathologic studies of the temporal bone in affected humans, and neither describes the findings in early gestation. We had the opportunity to study both temporal bones in each of two fetuses (22 and 24 weeks) exposed to isotretinoin in early gestation. One of the fetuses had a dilated IVth ventricle and a hypoplastic cerebellar vermis, while no dysmorphic features were seen in the other. In both infants the external ears were not noticeably abnormal. Histologically, anomalies of the middle ear included medial deviation of the malleus, forward displacement of the incus, and a small tympanic cavity (4/4); unilateral absence of the stapes (1/4); single "columella" crus and hypoplastic footplate (3/4); and unilateral dehiscence of the facial canal in one infant. Autolysis limited the examination of the labyrinth, but there was reduction in the number of cochlear spirals, and dilatation of the saccule in both infants. Anomalies of the middle and inner ear can be present without anomalies of the external ear or the central nervous system, and may be found even after relatively short exposures. These anomalies are similar to those detected in experimental exposure to isotretinoin, and are consistent with altered expression of the goosecoid gene.

Safety issues in isotretinoin therapy

Isotretinoin (Accutane, Roche Laboratories Inc, Nutley, NJ) is an important drug, not only for the treatment of severe acne, but also for other diagnoses and in chemoprevention settings. Because the use of isotretinoin is increasing, it is important for physicians to be aware of the adverse events, toxicities, and management issues related to its use. The most important issue is that of congenital defects, which has resulted in new pregnancy prevention policies and programs implemented by the manufacturer. A relatively new concern is that of depression associated with isotretinoin use, also resulting in new policies placed by the manufacturer and the FDA. The most common adverse effects observed during treatment are mucocutaneous and ocular in nature, but laboratory abnormalities and effects in the nervous, musculoskeletal, gastrointestinal, pulmonary, hematologic, and other systems are also described. Additionally, potential drug interactions, follow-up, and toxicity prevention measures are discussed.