What is Sjögren's syndrome?

Sjögren's syndrome

It is an autoimmune disorder affecting exocrine glands (e.g. salivary and lacrimal) resulting in dry mucosal surfaces. Though it may happen to both sex it is much more common in the females (ratio 9:1). The typical age of onset is between 40 and 50 years of age. It is associated with HLA-B8 and HLA-DR3.

Types of Sjögren's syndrome: It may be any of the following two:

• Primary Sjögren's syndrome (PSS) 
• Secondary to RA, SLE or other connective tissue disorders, where it usually develops around 10 years after the initial onset

Features:

• Eye symptoms: Dry eyes termed as keratoconjunctivitis sicca is the main eye problem. Conjunctivitis and blepharitis are quite common problems which may lead to filamentary keratitis (it occurs due to binding of tenacious mucous filaments to the cornea and conjunctiva.
• Oral symptoms: Dry mouth (xerostomia), dental caries and high risk of dental failure
• Rashes or skin irritation
• Plasma cell infiltration of salivary and lacrimal glands may occur e.g. Parotid swelling is found in Sjögren's syndrome
• Generalized osteoarthritis
• Fatigue (often the most disabling symptoms)
• Dry vagina
• Non-erosive arthralgia, myalgia
• Raynaud's phenomenon
• Sensory polyneuropathy
• Renal tubular acidosis (usually subclinical)
• There is a marked increased risk (40-60 folds) of lymphoid malignancy (NHL)
• SOX syndrome may be found (Sialadenitis, Osteoarthritis and Xerostomia)

Investigation:

• RF positive in nearly 100% of patients
• ANA positive in 70%
• Anti-Ro (SSA) antibodies in 70% of patients with PSS
• Anti-La (SSB) antibodies in 30% of patients with PSS
• Hypergammaglobulinaemia (↑ IgG) in 80%
• Low C4
• Raised ESR
• Schirmer's test: Placing filter paper near conjunctival sac to measure tears formation (wetting of less than 5 mm in 5 minutes indicates defective tear production).
• Rose Bengal staining of the eyes commonly shows punctuate or filamentary keratitis.
• Histology: focal lymphocytic infiltration in minor salivary gland biopsy
• Chest X-ray and lung function test (Interstitial lung disease can complicate PSS)

Management:

• For dry eyes: Artificial tears for keratoconjunctivitis sicca. Lacrimal substitute such as hypromellose should be used at daytime. In addition, during the night, more the viscous lubricating substitute should be used. A soft contact lens can be used to protect the cornea if filamentary keratitis develops
• For dry mouth: Artificial saliva sprays, saliva-stimulating tablets, pastilles and oral gel can be used for xerostomia but chewing gum is the most effective one
• Vaginal lubricants are used for dry vagina
• Adequate oral hygiene should be maintained following a meal. If oral fungal infections develop, prompt treatment is necessary
• Drugs used in Sjögren's syndrome:
• Systemic pilocarpine (5-30 mg daily in divided dose): Useful in the early stage of the disease
• Hydroxychloroquine (200 mg twice daily): May be helpful in skin conditions, musculoskeletal symptoms and in case of fatigue
• Immunosuppressive drugs (glucocorticoids and cyclophosphamide): essential in progressive interstitial lung diseases

Reference:

• Davidson’s Principles and practice of medicine 23^rd Edition; page: 1038
• 2- Step Up to MRCP Review Notes for P1 & P2 by Dr Khaled El Magraby 1^st edition; page: 696