Fact-sheet: Thyroid associated ophtalmopathy - Basedow


Updated on 11/16/2022 at 2:19 PM

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Definition

Orbitopathy associated with Graves Basedow disease.
May occur before thyroid dysfunction.

Population at risk: women, 40-60 years, smoking, thyroid dysfunction

Clinical features

  • exophthalmos: bilateral, axial, non-pulsatile, and reducible
  • eyelid signs: upper eyelid retraction, lid-globe lag
  • soft tissue involvement: edema and redness of the eyelids and conjunctiva
  • oculomotor disorders and diplopia
  • optic neuropathy from optic nerve compression; unilateral or bilateral decreased visual acuity
  • increased intraocular pressure
  • signs of thyroid dysfunction

Laboratory findings

Hyperthyroidism: elevated T3 T4 and decreased TSH; positive TSH receptor antibodies

Ultrasound

Thyroid Ultrasound findings in Graves Basedow disease:

  • Moderate goiter, diffusely hypoechoic and homogeneous
  • Thyroid inferno: hypervascularized goiter
  • Doppler of the thyroid arteries: increased peak systolic velocities > 100 cm/s

CT

Non-contrast orbital CT.

The semiology includes:

  • Exophthalmos. Relative to the interzygomatic line. Distance between the anterior surface of the globe and the line >= 23mm
  • Enlargement and fatty involution of the extraocular muscles. Most often bilateral (76-90%) and symmetric (70%). Correlation between muscle enlargement and the severity of Graves Basedow disease and the risk of optic nerve compression
  • Enlargement of the retro-orbital fat
  • Barrett index >= 60%: highly sensitive and specific for optic neuropathy
  • Enlargement of the lacrimal glands
  • Chemosis
  • Anterior displacement of the orbital septum

MRI

Orbital MRI: indication - clinically moderate to severe forms (Clinical Activity Score CAS > 2) - post-treatment evaluation of moderate to severe forms: improvement? - prior to surgical treatment or radioactive iodine therapy due to the risk of orbitopathy decompensation. Sequences: axial T2, coronal T1, T2, and T2 FatSat

  • Exophthalmos
  • Muscle hypertrophy (size > 5 mm except for the superior oblique > 4 mm)
  • Change in muscle signal (inflammatory or fatty)
  • Orbital fat hypertrophy, fat inflammation (T2 FS fat hyperintensity)
  • Optic nerve involvement: atrophy, T2 hyperintensity

Nuclear medicine

Thyroid scintigraphy:
diffuse and homogeneous hyperfixation of the isotope