This retrospective case review aimed to evaluate the frequency and extent of extraocular muscle enlargement in cases of acromegaly at presentation. All new presentations of acromegaly diagnosis at a single tertiary centre over a five-year period were screened for inclusion. A requirement for inclusion was the availability of computed tomography (CT) imaging. Patients also diagnosed with thyroid eye disease or history of other orbital disease were excluded. Age- and sex-matched controls were sought with non-functioning pituitary adenomas without history of thyroid eye disease or growth hormone dysfunction from the same centre over the same time period. The following data was extracted from medical notes: demographics, laboratory tests including growth hormone, insulin-like growth factor-1 (IGF-1), thyroid stimulating factor (TSH), free triiodothyronine (free T3) and free thyroxine (free T4) and CT imaging from initial presentation. The maximum diameter and cross-sectional area of all rectus muscles was measured by a single non-blinded neuroradiologist. A total of 17 patients were included in the study with a mean age of 50 years and 59% male. The 18 control participants were slightly younger with a mean age of 49 years and a higher proportion of males at 67%, however these differences were not found to be significant. IGF-1, random / fasting growth hormone, fasting glucose and free T4 were found to be higher and TSH lower in the acromegaly group compared with controls. The maximum diameter of all four rectus muscles was found to be significantly increased indicating these muscles to be enlarged in the acromegaly group. The medial and superior recti had the largest amount of difference. The authors acknowledge the following limitations of the study: measurement of the extraocular muscles was made on CT imaging without controlling for gaze deviation; the small sample size; and that the radiologist was not blinded. Acromegaly should be considered in the list of differential diagnosis in the presence of extraocular muscle enlargement.
Acromegaly associated with enlargement of extraocular recti muscles
Reviewed by Lauren Hepworth
Extraocular muscle enlargement in acromegaly.
CONTRIBUTOR
Lauren R Hepworth
University of Liverpool; Honorary Stroke Specialist Clinical Orthoptist, Northern Care Alliance NHS Foundation Trust; St Helen’s and Knowsley NHS Foundation Trust, UK.
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