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Show Letters to the Editor should be comprehensive if the transfer RNA A/G 3243 mutation is not found. Finally, we agree with the need to proactively test patients with MIDD for subclinical organ failure. Patients with MIDD are eligible for care at muscular dystrophy clinics, where there may be a monetary supplement to their private insurance. Although there is no cure for this disorder at the present time, preventive care may impact substantially on the quality of life. Jorge C. Kattah, MD Department of Neurology/Neurophthalmology, Illinois Neurologic Institute, University of Illinois College of Medicine at Peoria, Peoria, Illinois Palinopsia: Side Effect of Topiramate and Acetazolamide W e read with interest the recent articles by Yun et al (1) and Belcastro et al (2) describing palinopsia as a side effect of topiramate. This rare phenomenon, in which viewed images persist after the original visual stimulus is removed, can last from minutes to months (3). We evaluated a patient with acetazolamide-induced palinopsia. A 30-year-old obese woman, with previously treated idiopathic intracranial hypertension, complained of pulsatile tinnitus and chronic headache for a month. Examination revealed 20/20 visual acuity in each eye, normal ocular motility, full confrontational fields, and bilateral optic disc Simon R. Cardenas, MD Department of Neurology, Universidad Nacional Facultad de Medicina, Bogota, Colombia The authors report no conflicts of interest. REFERENCE 1. Cardenas SR, Saber Tehrani AS, Blume G, Kattah JC. Visual, ocular motor and cochleo-vestibular loss in patients with heteroplasmic maternally-inherited diabetes mellitus and deafness (MIDD), 3243 Transfer RNA Mutation. J Neuroophthalmol. 2016. in press. swelling. She was counseled about nutritional and low sodium dieting and prescribed acetazolamide 500 mg twice a day for 2 weeks and increased 1 tablet per week until tolerance of 2,000 mg daily. At that dose, she reported paresthesias in hands and feet, carbonation taste changes, difficulty concentrating, and cloudy urine. When stressed or when moving her hand in front of her face, the patient noted "ghost images" trailing her hand. Two months later, she expressed a desire to decrease the dose of acetazolamide due to the unpleasant side effects. Ophthalmic examination was unchanged. Acetazolamide was decreased to 1,500 mg and aggressive weight loss encouraged. However, the visual trailing effect became more frequent. She also experienced 2 new peculiar visual and tactile symptoms. She described seeing an image on FIG. 1. Illustration of persistent afterimage. Letters to the Editor: J Neuro-Ophthalmol 2016; 36: 343-352 347 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Letters to the Editor Facebook of a lotus pod flower. She began to see the same vivid image on walls, faces, and even with her eyes closed (Fig. 1). Although the patient understood the image was not real, it caused anxiety and insomnia. The lotus pod image appeared in different visual fields and would either appear randomly or triggered by patterns that reminded her of a lotus pod. She avoided coworkers who wore clothing similar to the lotus pod pattern and took precautions to avoid viewing flowers in her apartment complex. She reported a tactile sensation, described it as "feeling of things crawling on me but seeing nothing there," which differed from the "tingling or fuzzy" sensation associated with her paresthesias. Acetazolamide was discontinued with almost immediate resolution of all symptoms within 1 week. The patient refused a rechallenge. The pathophysiology of palinopsia is still unclear but hypotheses include an exaggeration of normal afterimage, seizure disorder, psychogenicity, or drug induction. Drugs with serotonin receptor activity, such as LSD, trazodone, and nefazodone, are known to cause drug-induced palinopsia (4). In our patient, palinopsia was induced by acetazolamide, a potent carbonic anhydrase inhibitor (5). After a thorough literature review, we found no other medications that inhibit carbonic anhydrase reported to induce palinopsia, except topiramate. The mechanisms of action of topiramate are unclear but include direct or indirect action on serotonin receptors and weak inhibition of Type II and Type IV carbonic anhydrase (5). Because topiramate and acetazolamide share carbonic anhydrase inhibition and not serotonin activity, it seems plausible that carbonic anhydrase inhibition maybe a mechanism that induces palinopsia. Our case highlights an unanticipated and previously undocumented side effect of acetazolamide. Palinopsia induced by medication maybe underreported due to patient Sildenafil-Induced Nonarteritic Anterior Ischemic Optic Neuropathy in a Patient With Pulmonary Hypertension W e read with interest the review article by Pomeranz (1) on the role of erectile dysfunction medications as a cause of nonarteritic anterior ischemic optic neuropathy (NAION). We evaluated a patient who developed NAION when taking sildenafil for the treatment of pulmonary hypertension. A 56-year-old woman reported segmental left visual field loss, which she described as a "veil." This was associated with heaviness in her left scalp. She had systemic lupus erythematous, which was treated with long-term low-dose corticosteroids. Complications of her lupus included glomerulonephritis and pulmonary hypertension with left ventricular failure, for which she had been prescribed sildenafil, 348 reluctance to report this unusual symptom. We encourage physicians to inquire about visual disturbances associated with acetazolamide. Peggy H. Vogt, BS FSU College of Medicine, Tallahassee, Florida Garrett Barr, BS TMH Foundation HealthCare, Tallahassee, Florida Charles G. Maitland, MD FSU College of Medicine, Tallahassee, Florida TMH Foundation HealthCare, Tallahassee, Florida The authors report no conflicts of interest. REFERENCES 1. Yun SH, Lavin PJ, Schatz MP, Lesser RL. Topiramate-induced palinopsia: a case series and review of the literature. J Neuroophthalmol. 2015;35:148-151. 2. Belcastro V, Aguglia U, Pisani LR, Ferlazzo E. Palinopsia and other reversible visual disturbances induced by topiramate. J Neuroophthalmol. 2015;35:329-330. 3. Meadows JC, Munro SS. Palinopsia. J Neurol Neurosurg Psychiatry. 1977;40:5-8. 4. Hoyt WF, Walsh FB, Miller NR, Newman NJ; Ovid Technologies Inc. Walsh and Hoyt's Clinical NeuroOphthalmology, 6th edition. Philadelphia, PA: Lippincott Williams & Wilkins, 2005. 5. Mula M. Topiramate and cognitive impairment: evidence and clinical implications. Ther Adv Drug Saf. 2012;3: 279-289. 10 mg 3 times daily. She had been on this medication for 7 years. She also had well-controlled blood pressure for which she was taking furosemide, 20 mg/d. On examination, visual acuity was 20/20 in left eye, with a left relative afferent pupillary defect and mild left optic disk swelling. She had a superior altitudinal visual field defect in her left eye and a cup-to-disc ratio of 0.7. Visual field testing in the right eye was entirely normal and the right cup-to-disc ratio was normal. She had a sedimentation rate of 42 mm/h and a C-reactive protein of 4 mg/L (normal #5.0 mg/L). Complete blood count and serum chemistries were normal, and there was no evidence of active lupus vasculitis. Because of rapid evolution of vision loss, she was admitted for further investigation and for pulsed intravenous methylprednisolone. Sildenafil also was discontinued. A temporal artery biopsy was performed and was negative for giant cell arteritis. At discharge from hospital, her visual field defect was slightly improved. Letters to the Editor: J Neuro-Ophthalmol 2016; 36: 343-352 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. |
