Current RMA Instruments
| Reasonable Hypothesis SOP | 11 of 2021 |
| Balance of Probabilities SOP | 12 of 2021 |
Changes from previous Instruments
ICD Coding
- ICD-9-CM Codes: 446.5
- ICD-10-AM Codes: M31.5, M31.6
Brief description
This is a type of systemic vasculitis that most commonly involves the large and medium arteries of the head, particularly the temporal arteries.
Confirming the diagnosis
The diagnosis may be suspected on clinical grounds. A combination of clinical findings, laboratory test results and colour Doppler ultrasound imaging may allow a diagnosis to be made, but temporal artery biopsy will be needed in a proportion of cases. Because of the risk of visual loss and the need for aggressive steroid therapy the diagnosis needs to be made unequivocally.
The relevant medical specialist is a physician, rheumatologist and/or ophthalmologist.
Additional diagnoses covered by SOP
- Cranial arteritis
- Giant cell arteritis with polymyalgia rheumatica
- Horton’s disease / syndrome
- Temporal arteritis
Conditions not covered by SOP
- Polymyalgia rheumatica (without giant cell arteritis)*
* another SOP applies.
Clinical onset
The condition affects persons over 50 years of age, with peak incidence between ages 70 and 79. Initial symptoms may include new headaches, visual disturbances, jaw pain brought on by chewing and non-specific fever, fatigue or other consitutional symptoms. Onset tends to be subacute.
Clinical worsening
Appropriate management includes careful evaluation of the diagnosis and treatment with high dose corticosteroids. Disease and treatment duration is variable. The condition may resolve over a year or two or persist for longer. Treatment can be tapered and eventually discontinued in most patients.