What is psoriatic arthritis?
Psoriatic arthritis is chronic inflammatory rheumatism (CIA) characterized by inflammatory pain (waking up at night, severe morning fatigue, worsening of symptoms at rest). In 90% of cases, psoriatic arthritis affects people with psoriasis or a history of psoriasis.
Psoriasis precedes the onset of joint pain by 10 to 12 years in 75% of cases. Occasionally, dermatological and common symptoms appear at the same time in 15% of cases. In one in ten cases, rheumatic pain precedes skin problems.
They are classified into three categories:
Auto-inflammatory diseases: they are caused by a dysfunction of the innate immune system, that is, the body’s first line of defense designed to counter the penetration and/or proliferation of pathogens. Innate immunity causes an immediate inflammatory response, regardless of the specific disease it is fighting. It involves three types of cells: phagocytic, granulocytic, and NK cells.
Autoimmune diseases are related to a dysfunction of acquired immunity. Acquired immunity involves specialized cells depending on the infectious agent: B cells (responsible for the production of specific antibodies) and T cells (the cells that coordinate acquired immunity).
Inflammatory diseases of undetermined origin
Definition of psoriatic arthritis:
Psoriatic arthritis is a chronic inflammatory disease of the joints that progresses in flare-ups.
It is an autoimmune disease: the patient’s immune system mistakenly attacks his or her own joints, causing inflammation and, if not treated early, joint damage. The result is joint pain and sometimes severe difficulty in performing specific movements.
This type of arthritis has the particularity of being generally associated with psoriasis.
In about 80% of cases, psoriasis precedes the onset of psoriatic arthritis.
In 15% of cases, psoriatic arthritis precedes dermatological disease.
In 5% of cases, the two conditions occur simultaneously.
Psoriatic arthritis affects between 0.5% and 1% of the population. Men and women are affected equally. The peak of clinical manifestations is usually between the ages of 30 and 50, although the disease can appear at any age. There is also a childhood form of the disease: juvenile psoriatic arthritis.
-Evolution by flare-ups
The course of psoriatic arthritis is generally slow and variable over time. Most of the time, psoriatic arthritis evolves by flare-ups, interspersed with periods of remission of varying length, during which the symptoms are less marked.
If left untreated, joint damage can spread, eventually causing stiffness and deformity. This is why early treatment is beneficial.
Causes of psoriatic arthritis :
The exact causes of psoriatic arthritis are still unknown. However, certain factors may favor the occurrence of the disease and/or an inflammatory flare-up:
-Genetic factors: having a family history of psoriasis or psoriatic arthritis, personal account of psoriasis or nail psoriasis.
-Immune factors: abnormal immune responses are targeting one’s own tissues and structures.
-Environmental factors: such as smoking, ENT infections, stress, alcohol consumption, certain medications.
-Other factors: overweight or obesity, age (between 30 and 50 years), Caucasian type.
-Joint symptoms of psoriasis:
Psoriatic arthritis affects the joints and the insertion points of tendons and ligaments, an area known as the enthesis. The locations vary -depending on the patient:
-Inflammatory involvement of the entheses, i.e., the insertion of tendons and ligaments on the bone (elbow, heel, sole of the foot);
-Peripheral joint involvement: fingers and toes (especially the last joints called distal interphalangeal joints), hip, knee, shoulder. The damage is often asymmetrical (the two sides of the body are not affected equally).
-Axial involvement, i.e., of the spine, sacroiliac joints (joints located in the buttock between the sacrum and the iliac bone), and the thoracic cage joints (sternum and ribs).
The inflammation of the joints is manifested by:
-Joint pain: usually occurs at rest, often at the end of the night, and maybe responsible for waking up at night. The complaints typically improve after the patient has moved, but not always.
-A feeling of heat.
-Swelling (due to inflammation and fluid accumulation in the joint).
We speak of flexibility when the attack affects the fingers or the whole toes, taking on a “pudgy” appearance.
In the absence of effective treatment, the patient may suffer from joint deformities (“mutilating” arthritis) and a progressive mobility reduction.
Generalized inflammatory disease:
Many scientists consider psoriatic arthritis to be a generalized inflammatory disease because of its many forms (organs, tissues, joints). The severity of the inflammation – and therefore of the symptoms – varies from patient to patient and has varying degrees of impact on social, family, and professional life.