In severe forms, psoriatic arthritis may progress to arthritis mutilans which on X-ray gives a "pencil-in-cup" appearance.Because prolonged inflammation can lead to joint damage, early diagnosis and treatment to slow or prevent joint damage is recommended. Causes
The exact causes are not yet known, however silica dust exposure has been identified in Australia and a number of genetic associations have been identified in a genome-wide association study of psoriasis and psoriatic arthritis including HLA-B27. Diagnosis
There is no definitive test to diagnose psoriatic arthritis. Symptoms of psoriatic arthritis may closely resemble other diseases, including rheumatoid arthritis. A rheumatologist (a physician specializing in autoimmune diseases) may use physical examinations, health history, blood tests and x-rays to accurately diagnose psoriatic arthritis. Factors that contribute to a diagnosis of psoriatic arthritis include the following:

Psoriasis in the patient, or a family history of psoriasis or psoriatic arthritis. A negative test result for rheumatoid factor, a blood factor associated with rheumatoid arthritis. Arthritis symptoms in the distal Interphalangeal articulations of hand (the joints closest to the tips of the fingers). This is not typical of rheumatoid arthritis. Ridging or pitting of fingernails or toenails (onycholysis), which is associated with psoriasis and psoriatic arthritis. Radiologic images demonstrating degenerative joint changes.Other symptoms that are more typical of psoriatic arthritis than other forms of arthritis include enthesitis (inflammation in the Achilles tendon (at the back of the heel) or the plantar fascia (bottom of the feet)), and dactylitis (sausage-like swelling of the fingers or toes).
Caffeine/ergotamine (trade name Cafergot) is the proprietary name of a medication consisting of ergotamine tartrate and caffeine. This combination is used for the treatment of headaches, such as migraine headache. Use
Correct timing of use is important. Cafergot is an abortive headache treatment, which prevents the development of the headache, rather than a treatment for an established headache. The medication should be administered at the first sign of headache. There exist some limitations as to the maximum number of tablets that can be taken per day per week. Different sources of drug information may carry different information, and patients are encouraged to ask their pharmacist or prescriber about such details. Cafergot is currently available as a generic drug (ergotamine tartrate/caffeine)

Mechanism of action
According to a topic review on UpToDate, "ergotamine and dihydroergotamine (DHE 45) bind to 5HT 1b/d receptors, just as triptans do." This along with binding to other serotonergic and dopaminergic receptors is their presumed mechanism of action in treating migraine. Adverse effects
Because the vasoconstrictive effects of ergotamine and caffeine are not selective for the brain, adverse effects due to systemic vasoconstriction can occur. Cold feet or hands, angina pectoris, myocardial infarction, or dizziness are some examples. == References ==