methimazole and Perceptual-Disorders

Upside-down reversal of vision (UDRV) is a rare form of metamorphopsia, or visual illusions that can distort the size, shape or inclination of objects. This phenomenon is paroxysmal and transient in nature, with patients reporting a sudden inversion of vision in the coronal plane, which typically remains for seconds or minutes, though occasionally persists for hours or days, before returning to normal. Distorted egocentric orientation (ie, the patient perceives the body to be tilted away from the vertical plane) is even more rare as a co-occurring phenomenon. To the best of our knowledge, this is the first reported case of a veteran who presented with UDRV and distorted egocentric orientation during hospitalisation on an inpatient physical medicine and rehabilitation setting following an elective hip surgery. This case serves not only to document the presence of rare visual illusions, but also illustrates the importance and value of an interdisciplinary team approach.

Topics: Aged; Antithyroid Agents; Arthroplasty, Replacement, Hip; Casts, Surgical; Endocrinology; Graves Disease; Hip Dislocation; Hospitals, Veterans; Humans; Illusions; Male; Methimazole; Neuropsychology; Patient Care Team; Perceptual Disorders; Postoperative Complications; Psychiatry; Reoperation; Veterans; Vision Disorders

Thyroid hormones (THs) are essential for proper brain development in mammals. TH insufficiency during early development causes structural and functional abnormalities in brain leading to cognitive dysfunction. The specific effects of developmental hypothyroidism on attention have not been well characterized in animal models. The present study was conducted to characterize the effects of developmental hypothyroidism on attention in rats, and tested the hypothesis that the hypothyroidism has adverse impacts on attention by means of a visual signal detection task. Pregnant rats were exposed to the anti-thyroid drug, methimazole (0.02% w/v) via drinking water from gestational day 15 through postnatal day (PND) 21 to induce maternal and neonatal hypothyroidism. Male offspring served as subjects for the task started on PND 90. A light stimulus (500 ms, 250 ms or 50 ms) was presented in signal trials and not in blank trials. The offspring were required to discriminate these signal events, and subsequently press the correct lever. The correct response for signal and non-signal events was considered as hit and correct rejection, respectively. The hypothyroid offspring exhibited a decreased hit response for short signals (250 ms and 50 ms) which requires the higher attentional demand. The total number of lever responses during inter-trial interval (ITI) was also increased in the hypothyroid group. The number of lever responses was negatively correlated with a hit response at 50 ms, not at 250 ms. These results suggest that developmental hypothyroidism disrupts signal detection performance via impairment of visual attention and the altered lever response behavior.

Topics: Age Factors; Analysis of Variance; Animals; Animals, Newborn; Antithyroid Agents; Attention; Body Weight; Conditioning, Operant; Female; Hypothyroidism; Male; Methimazole; Perceptual Disorders; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Reaction Time; Reinforcement, Psychology; Signal Detection, Psychological