Graves orbitoptathy Flashcards
what is the incidence of graves orbitopathy
The estimated incidence of GO is 16 women or 3 men per 100,000 person per year
Prevalence: 400 000 people in the UK with GO
Compare with Type 2 diabetes:
One in ten people over 40 in theUKare now living with a diagnosis of Type 2diabetes
Prevalence: 3.4 million people in the UK with a diagnosis of Type 2diabetes
what is the incidence of graves orbitopathy
The estimated incidence of GO is 16 women or 3 men per 100,000 person per year
Prevalence: 400 000 people in the UK with GO
Compare with Type 2 diabetes:
One in ten people over 40 in theUKare now living with a diagnosis of Type 2diabetes
Prevalence: 3.4 million people in the UK with a diagnosis of Type 2diabetes
describe the thyroid gland
Highly vascular endocrine organ
Lower neck anterior to trachea between the sternocleidomastoid muscles
Consists of densely packed follicles
Function
concentrates iodide to form thyroid hormones
Thyroid hormones synthesised and stored in the follicles
what does the thyroid hormone release
TRH stimulates release of TSH
TSH is secreted by the anterior pituitary and stimulates secretion of
T3 – Tri-iodothyronine
T4 - Tetra-iodothyronine (Thyroxine)
T3 & T4 secreted into bloodstream:
bound to plasma proteins
free form - intracellular
what are the role of thyroid hormones
Growth and Development
rate of growth of many tissues
maturation of CNS and bones
regulation of synthesis of some respiratory enzymes
Metabolic Effects
regulation of basal metabolic rate
regulation of water and ion transport
regulation of calcium and phosphorus metabolism
regulation of cholesterol and fat metabolism
regulation of nitrogen metabolism
what is hyperthyroidism
Enlarged thyroid gland – goitre
Abnormal heart rhythms – tachycardia
Increased appetite but may have weight loss
Hand tremors
Fine brittle hair
Hyperactivity
Heat intolerance and increased perspiration – warm, moist skin
Lighter or less frequent periods
Irritability
Anxiety
Muscle weakness – upper arms and thighs
what is hypothyroid (under active)
Fatigue, exhaustion
Feeling run down and sluggish
Unexplained / excessive weight gain
Dry, coarse, itchy skin and hair
Slow heart rate
Feeling cold – especially in the extremities
Goitre
More frequent periods, increased menstrual flow
Difficulty concentrating – brain fog
Hoarse voice
Muscle cramps
how to diagnose thyroid abnormalities
TSH – (considered outside normal if lower than 0.3 or higher than 3.0)
- Calculated free T4 index (10-20 pmol/L)
- Thyroid-stimulating immunoglobulin (TSI)
- Anti-thyroid antibodies
- Serum T3 (2.5 – 5.3 pmol/L)
what is the management for hyperthyroidism
Drug therapy
Radioactive iodine treatment
Thyroidectomy
what drugs are used for hyperthyroidism
Drug therapy
Thinomines (Carbimazole, Methamizole, Propylthiouracil) Interfere with thyroid hormone synthesis by blocking the build up of iodine. Most effective if the onset of disease within 1 year
Steroids (oral Prednisone) Decreases secretion of thyroid hormones and peripheral conversion of T4 and T3. Used in severe cases
Immunosuppressants (Azathioprine or Rituximab)
how is radioactive iodine used for hyperthyroidism
Radioactive iodine
- Radioactive iodine introduced to the body and taken up by the thyroid gland. Normal cell division and function is disturbed.
- Generally used on patients over 45 years of age or in younger patients if other treatments are contraindicated.
- 20% of patients become hypothyroid within 1 year of the treatment
- Ocular symptoms have been found to worsen following this treatment (Acharya 2008)
what does radioactive iodine and corticosteroids do in hyperthyroidsim
Prevents progression of GO in patients with pre-existing eye disease
Eye signs worsened in 6 months in:
15% after RI
2.7% after antithyroid drugs (carbimazole)
None who had RI and prednisone
what is a thyroidetomy in hyperhyroidism
removal of thyroid gland
Removal of most of the thyroid gland
Reduces hormone production
Post-op recurrence in 10-15% of patients
Post-op hypothyroidism in 40% of patients
Usually performed in younger patients
what medication is given for hypothyroidism
oral thyroxine
what is graves disease
Graves’ disease is an autoimmune disorderthat causes hyperthyroidism. The immune systemattacks the thyroid and causes it to make more thyroid hormone than the body needs
what percentage of people with graves disease have graves orbitopathy
Approx 40% of GD have GO
define graves orbitopathy
Auto-immune disease
Disease of the orbit affecting the orbital soft tissues
Closely correlated to auto-immune (systemic) thyroid disease (Graves’ Disease)
Prescence of circulating antibodies that bind and stimulate the thyroid hormone receptor (TSH) leading to hyperthyroidism and goitre.
what are the risk factors for graves disease
Genetic
Environmental
Smoking
Stress
Immune factors
what populations are most affected by graves orbitopathy
Male / female
female - 86%
16/10 000 women
3/10 000 men
Age
women 45-50 years
men 50-55 years (> severity)
Greater severity with age
(Lin et al 2008)
what are the risk factors for smoking
Smoking
Main known risk factor 7-8 fold increase
Severity of eye signs and symptoms increased with increased tobacco consumption (Shine et al, 1990 Lancet)
what type of thyroid problem do most people with graves orbitopathy have
Hyperthyroidism 90%
Hypothyroid 3-5%
Euthyroid 5% ? Sensitivity of detection
Patients hyperthyroid without eye signs = 50-60%
80-90% have EOM changes on CT imaging
what is the natural history of graves orbitopaty
natural history is called bundles curve
active phase where their is inflammation for 1-3 years and then fibrosis = inactive phase 3 years and later where fibrosis occurs
what are the stages of graves orbitopathy
Wet / Congestive / Inflammatory / Active phase
Eyes are painful and red
Can last around 3 years
Dry / Fibrotic / Inactive phase
Eyes are white
Painless, restrictive myopathy may be present
what is the history of graves orbitiopathy
Signs
Lid retraction
– 90-98%
Lid lag – von Graefe’s sign
Exophthalmos (proptosis)
Lid oedema
Periorbital oedema
Epiphora
Visual loss – Dysthyroid optic neuropathy DON ~5%
Chemosis
Strabismus – Eso/ Hypo
AHP
Thyroid disease
what lid symptoms do people with graves have
upper lid , lower lid and palpebral appeture lid retraction
how to measure lid retraction
Position patient’s head correctly
Ask patient to fixate on target positioned at their eye level and in the distance.
Ask patient to relax as much as possible to record the minimum amount of retraction for that patient (i.e. Müller’s muscle as relaxed as possible).
Observer holds vertical clear plastic ruler near to visual axis without touching eyelashes
Observer should consistently use only one of their eyes, and on same horizontal level as patient’s eye.
For patients with manifest strabismus, the contralateral visual axis is occluded prior to measurement.
Record in mm
what is used to measure exopthalomos/ propotosis
hertel mirrpor exopthalmoeter
what are the normal ranges for exopthalmost
12-21
12-33
12-20
12-24
what do you need to note when measuring exopthalmos
Bilateral
Asymmetric
Unilateral ?
Normal
exophthalmometry >22mm or
asymmetry greater than 3mm
Amount depends on severity of disease/ inflammation and structure of anterior orbital septum
Axial / non-axial
what happens during the wet/actve phase of ted
Wet phase – Active phase
Cellular infiltration with glycosaminoglycans (GAGs) and osmotic inhibition of water
This leads to EOMs becoming up to 8-10x enlarged
May compress ON leading to visual loss
Subsequent degeneration of muscle fibres leads to fibrosis resulting in restriced motility and diplopia
This phase tends to settle within 3 years
what happens to the eom during the dry/fibrotic phase
Fibrotic Phase / Dry Phase
Muscle fibres become distorted, contracted and damaged due to fibrosis
Eyes are white and quiet
Painless, restrictive myopathy may be present
what can be seen on a MRI of eom
enlarged by 10 times muscle but not tendon
what would you see on ocular movements
Limitation
Reversal
Saccades
Cog wheel pursuit
Fatigue
Pain
Retraction
Bilateral involvement
what is the order of eom involvement
IR
MR
SR, LR
SO, IO (Thacker et al 2005)
Vertical, horizontal and torsional diplopia
Swelling of EOM results in restriction: if IR affected then pt unable to elevate as eye becomes tethered down
