Reactive arthritis

Reactive arthritis aka Reiter's syndrome aka Reiter's disease aka arthritis urethritica, venereal arthritis, seronegative spondyloarthropathy, polyarteritis enterica.

Reactive arthritis is a RF-seronegative, HLA-B27-linked spondyloarthropathy with symptoms similar to arthritis or rheumatism. It is caused by genitourinary or gastrointestinal infections, and is thus "reactive", i.e. dependent on the other condition.

Reactive arthritis is the combination of three seemingly unlinked symptoms:

1. an inflammatory arthritis of large joints
2. inflammation of the eyes (conjunctivitis and uveitis), and
3. urethritis.

Epidemiology

• Most commonly strikes individuals aged 20-40.
• More common in men than in women.
• More common in white men than in black men due to white individuals being more likely to have tissue type HLA-B27 than black individuals.
  
• People with HIV have an increased risk of developing reactive arthritis.

History

Reactive arthritis was first described by Hans Reiter, a German military physician, who in 1916 described the disease in a World War I soldier who had recovered from a bout of diarrhea.

The term Reiter's syndrome is being phased out, partly due to a move in the field of medicine to give descriptive names, rather than personal names, to conditions, and partly due to Dr. Reiter's experiments in Nazi concentration camps.

Causes

• Reactive arthritis is set off by a preceding infection, the most common of which would be a genital infection with Chlamydia trachomatis.
• Other bacteria known to cause reactive arthritis are Neisseria gonorrhoeae, Ureaplasma urealyticum, Salmonella spp., Shigella spp., Yersinia spp., and Campylobacter spp..
• A bout of food poisoning or a gastrointestinal infection may also trigger the disease.
• Reactive arthritis usually manifests about 1-3 weeks after a known infection.

Pathophysiology

The mechanism of interaction between the infecting organism and the host is unknown.

Synovial fluid cultures are negative, suggesting that RA is caused either by an over-excited autoimmune response or by bacterial antigens which have somehow become deposited in the joints.

Signs and symptoms

• Symptoms generally appear within 1-3 weeks but can range from 4-35 days from the onset of the inciting episode of the disease.
• The classical presentation is that the first symptom experienced is a urinary symptom such as burning pain on urination (dysuria) or an increased need to urinate (polyuria or frequency).
• Other urogenital problems may arise such as prostatitis in men, and cervicitis, salpingitis and/or vulvovaginitis in women.
• The arthritis that follows usually affects the large joints such as the knees causing pain and swelling with relative sparing of small joints such as the wrist and hand.
• Eye involvement occurs in about 50% of men with urogenital reactive arthritis and about 75% of men with enteric reactive arthritis. Conjunctivitis and uveitis can cause redness of the eyes, eye pain and irritation, and blurred vision.
• Roughly 20 to 40 percent of men with reactive arthritis develop penile lesions called balanitis circinata (circinate balanitis) on the end of the penis. A small percentage of men and women develop small hard nodules called keratoderma blennorrhagica on the soles of the feet, and less often on the palms of the hands or elsewhere. In addition, some people develop mouth ulcers that come and go. In some cases, these ulcers are painless and go unnoticed.
• About 10 percent of people with Reactive Arthritis, especially those with prolonged disease, will develop cardiac manifestations including aortic regurgitation and pericarditis.

Commonly remembered with the mnemonic "Can't See, Can't Pee, Can't Climb a Tree"

Diagnosis

There are countless clinical symptoms, but the clinical picture is dominated by polyarthritis. There is pain, swelling, redness, and heat in the joints. MRI's are effective for diagnosis.

The urethra, cervix and throat may be swabbed in an attempt to culture the causative organisms. Cultures may be carried out on urine and stool samples.

Synovial fluid from an affected knee may be aspirated to look at the fluid under the microscope and for culture.

A blood test for the gene HLA-B27 may be given to determine if the patient has the gene. About 75 percent of all patients with Reiter's Syndrome have the gene.

Treatment

• The main goal of treatment is to identify and eradicate the underlying infectious source with the appropriate antibiotics.
• Treatment is symptomatic for each problem. Steroids and analgesics may be given for severe joint inflammation.
  
• Immunosuppressants may be needed for patients with severe reactive arthritis who do not respond to any other treatment.

Prognosis

• Reactive arthritis may be self limiting, frequently recurring or develop continually.
• Most patients have severe symptoms lasting a few weeks to six months.
• Approximately 15 to 50 percent of cases have recurrent bouts of arthritis.
• Chronic arthritis or sacroiliitis occurs in 15-30 percent of cases.
• Repeated attacks over many years is common, and more than 40 percent of the patients end up with chronic and disabling arthritis, heart disease or impaired vision.
• However, most people with reactive arthritis can expect to live normal life spans and maintain a near-normal lifestyle with modest adaptations to protect the involved joints.

References:

• http://en.wikipedia.org/wiki/Reiter%27s_disease

Molar pregnancies

Molar pregnancy aka Hydatidiform mole aka mola hydatidiforma is a common complication of pregnancy, occurring once in every 1000 pregnancies in the US, with much higher rates in Asia (e.g. up to one in 100 pregnancies in Indonesia).

It consists of a nonviable embryo which implants and proliferates within the uterus.

Clinical presentation

Molar pregnancies usually present with painless vaginal bleeding in the fourth to fifth month of preganancy.

Diagnosis

• Ultrasound makes the definitive Dx - the uterus may be larger than expected, or the ovaries may be enlarged.
• There may also be hyperemesis (more vomiting than would be expected).
• Sometimes there is an increase in BP along with proteinuria.
• Blood tests will show very high levels of hCG.
• Sometimes symptoms of hyperthyroidism are seen, due to the extremely high levels of hCG, which can mimick the normal TSH.

Pathophysiology

• A mole is characterized by a conceptus of hyperplastic trophoblastic tissue attached to the placenta. The conceptus does not contain the inner cell mass (the mass of cells inside the primordial embryo that will eventually give rise to the fetus).
• The hydatidiform mole can be of two types: a complete mole, in which the abnormal embryonic tissue is derived from the father only; and a partial mole, in which the abnormal tissue is derived from both parents.

Treatment

• Hydatidiform moles should be treated by evacuating the uterus by uterine suction or by surgical curettage as soon as possible after diagnosis.
• Patients are followed up until their serum hCG titre has fallen to an undetectable level.
• Invasive or metastatic moles often respond well to methotrexate. The response to treatment is nearly 100%.
• Patients are advised not to conceive for one year after a molar pregnancy.
• The chances of having another molar pregnancy are approximately 1%.

References:

• http://en.wikipedia.org/wiki/Molar_pregnancy
  

Ring Blocks

A digital ring block (aka digital block) is the technique of blocking the nerves of the digits to achieve anesthesia of the finger(s). It is a useful procedure to facilitate minor surgery of the finger.

The nerves to be blocked are the palmar and dorsal digital nerves.

The two palmar nerves supply the anterior aspect of the fingers and are the terminal branches of the median nerve (lateral 3 1/2 fingers) and ulnar nerve (little finger and 1/2 ring finger).

The two dorsal nerves supply the posterior aspect of the fingers and arise from the radial nerve (lateral 2 1/2 to 3 1/2 fingers) and ulna nerve (medial 1 1/2 to 2 1/2 fingers).

If seen in cross section the nerves are at two, five, seven and ten o'clock positions

The procedure:

• The patient's hand and fingers are extended and fingers abducted from each other.
  
• The head of the metacarpal bone and base of the proximal phalanx is felt.
  
• The skin is cleaned.
• The needle is introduced between the fingers at the point of the interdigital fold and a skin wheal is raised. This is at the level of the head of the metacarpal bone.

• The needle is advanced along the axis of the fingers until the palmar aponeurosis is
  reached which is felt as a resistance.
  
• Before injection of local anaesthetic the needle must be aspirated to prevent intra-
  vascular injection.
  
• 1 to 2 mls of local anaesthetic is introduced as the needle is withdrawn.
  
• Subcutaneous injection around the base of the finger is then done through the same skin
  wheal to block the palmar and dorsal digital nerves.
• The procedure is repeated on the opposite side of the finger.
  
• Massaging the finger after infiltration facilitates spread and increases absorption of the
  local anaesthetic.
  

References:

• "Digital Ring Block", Dr. Mary Daniels, Department of Anaesthesia, The Chinese University of Hong Kong, http://sunzi1.lib.hku.hk/hkjo/view/23/2300620.pdf
• "Digital Nerve Block", Dr A Hazdic, New York School of Regional Anaesthesia, http://www.nysora.com/techniques/digital_block/
  

Marcain

Composition

Bupivacaine hydrochloride +/- Adrenaline

Actions

Bupivacaine is classed as a membrane stabilising agent and is a local anaesthetic of the amide type. Like all amines it causes a reversible blockade of impulse propagation along nerve fibres by preventing the inward movement of sodium ions through the nerve membrane.

Pharmacokinetics

Bupivacaine is a long acting, amide type local anaesthetic chemically related to lignocaine and mepivacaine. It is approximately four times as potent as lignocaine.

References:

• MIMS
  

Indomethacin

Drug class

NSAID

Action

Potent inhibitor of prostaglandin synthesis. Affords relief of symptoms but does not alter the progressive course of the underlying disease.

Uses

Arthritis and related inflammatory disorders; low back pain; postop bone pain; primary dysmenorrhoea, IBD.

Contraindications

NSAID sensitive asthma; active peptic ulcer, recurrent GI ulceration; pregnancy, lactation

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Athrexin