The major pathological processes

VASCULAR

Atherosclerosis

• Causes - HT, DM, Smoking, Hyperlipidaemia
• Examples - Angina
• Time course - chronic
• Complications - thrombus>embolus>distant ischaemia/infarction, aneurysm>rupture>haemorrhage
• Tests - vascular ultrasound, arteriography
• Treatment - stenting, endarectectomy, vascular bypass

Arterial thromboembolic

• Sources - (see arteriosclerosis), cardiac arrhythmia, myocardial infarction
• Example - Ischaemic stroke
• Time course - abrupt, acute
• Complications - ischaemia, infarction
• Tests - enzymes from damaged tissue e.g. CKMB/myocardial infarct, anteriography, CT with arterial contrast, organ dysfunction e.g. echocardiogram & cardiac contraction, creatinine and renal function
• Treatment - anticoagulants, thrombolytics, antiplatelets, surgical removal

Venous thrombo-embolic

• Causes - Vichov's triad - abnormal flow, vessel wall, blood
• Example - Deep vein thrombosis
• Time course - acute
• Complications - venous infarction, pulmonary embolism>pulmonary hypertension>circulatory shock
• Tests - vascular ultrasound, venography, CT with venous contrast
• Treatment - anticoagulants, thrombolytics, antiplatelets

INFECTION

Acute infection

• Causes - bacterial, viral
• Example - pneumoccoccal pneumonia, cholera gastroenteritis
• Time course - acute
• Complications - septicaemia, abscess formation (with local pressure effects)
• Tests - inflammatory markers - WCC, CRP, ESR, microbiological/serological tests
• Treatment - antimicrobials, drain abscess, debride infected tissue

Chronic infection

• Causes - bacterial, viral, rickettsial, mycobacterial, fungal, prion
• Example - tuberculosis
• Time course - chronic
• Tests - (see acute infection)
• Treatment - antimicrobials

IMMUNOLOGICAL

Immunological - General

• Causes - Immune reaction to foreign substance
• Tests - Inflammatory markers, Ig, complement, immune cell
• Complications - depends on organ affected
• Treatment - immunomodulators

Immunological - Type I hypersensitivity

• Causes - IgE mediated
• Examples - environmental allergens, medication, arthropod bites, food
• Time course - abrupt
• Complications - angioedema, brochospasm, circulatory collapse
• Tests - tryptase
• Treatment - adrenaline, steroids

Immunological - Type II hypersensitivity

• Causes - Antibody mediated
• Examples - transfusion reaction
• Time course - acute, sub-acute

Immunological - Type III hypersensitivity

• Causes - Immune complex (immunoglobulin + antigen complex deposition)
• Examples - immunisation reactions, SLE
• Time course - sub-acute, chronic

Immunological - Type IV hypersensitivity

• Causes - Cell mediated (T cell)
• Examples - chronic dermatitis, chronic transplant rejection
• Time course - sub-acute, chronic

Immunological - Type V hypersensitivity (Autoimmunity)

• Causes - Receptor cross-reactivity (i.e. antibodies against an antigen also attack normal tissue receptors) - NON RECOGNITION OF SELF
• Examples - Grave's disease, Coeliac disease, Guillain-Barre
• Time course - sub-acute, chronic

Immunodeficiency

• Causes - Congenital (v immune cells or formed elements), Drugs (immunosupressants, immunomodulators), Infection, Radiation
• Examples - HIV, anti-transplant rejection drugs
• Time course - sub-acute, chronic
• Complications - infection / sepsis
• Treatment - see infection

TRAUMA

Physical Trauma - acute

• Causes - sudden, severe mechanical force
• Time course - abrupt
• Complications - organ disruption - laceration, fracture, avulsion, amputation
• Tests - imaging studies (XR, CT, Ultrasound)
• Treatment - surgical repair

Physical Trauma - chronic, repetitive

• Causes - repeated minor trauma
• Time course - sub-acute, chronic
• Complications - inflammation, minor structural disruption, pain
• Tests - imaging studies (XR, CT, Ultrasound), nuclear scan
• Treatment - rest, physical therapy, ?surgical repair

Thermal Trauma

• Causes - excess heat or cold exposure
• Time course - abrupt, acute, sub-acute (depends on magnitude)
• Complications - infllamation, scarring, necrosis
• Treatment - dressing, surgery

Chemical Trauma

• Causes - chemical irritant
• Time course - abrupt, sub-acute, chronic (depends on dose)
• Complications - inflammation, chemical burn, teratogenesis
• Tests - imaging studies (XR, CT, Ultrasound), nuclear scan
• Treatment - see Thermal trauma

Radiological trauma

• Causes - ionising (alpha, beta particles) and non-ionisining radiation (xrays, gamma rays) including medical radiation theraphy
• Time course - acute, sub-acute or chronic (depends on dose)
• Complications - bone marrow depression (acute), GIT epithelial injury, skin/hair damage (sub-acute), malignancy, teratogenesis
• Tests - full blood count, bone marrow biopsy
• Treatment - GCSF + ?antidote

Toxic

• Causes - medication (prescribed, OTC, recreational), occupational exposure
• Example - heroin overdose, carbon monoxide inhalation
• Time course - acute, sub-acute, chronic (depends on dose)
• Complications - depends on susceptible organ and route of exposure
• Tests - supportive therapy +/- antidotes

Metabolic

• Causes - abnormal biochemical pathways resulting in deficiency or excess of substrates and metabolities (may be congenital or acquired)
• Time course - acute, sub-acute, intermittent (can be precipitated by exposure to certain diet or medications)
• Complications - depends on susceptible organ
• Tests - Measure substrates or metabolities (e.g. DM/Blood sugar, liver disease/ammonia)
• Treatment - dietary modification, replace or bypass metabolic pathways (e.g. L-dopa for Parkison's disease)

Endocrine

• Causes - abnormal regulation of biochemical and physiological pathways Time Time course - Depends on degree of failure, see also Metabolic
• Examples - thyrotoxicosis, diabetes mellitus
• Complications - depends on susceptible organ
• Tests - see metabolic
• Treatment - hormone replacement (if deficient), remove or suppress endocrine organ (if excess) - see also Neoplastic, Immunological, Toxic

Neoplastic (Benign or Malignant)

• Causes - abnormal and unregulated growth of tissue
• Example - bowel cancer, lung cancer
• Time course - chronic (but may have acute complications)
• Complications - local pressure effects (e.g. pain, organ dysfunction, bleeding, infarction, nerve damage), metastases (in malignancy), paraneoplastic effects (e.g.ectopic hormone release)
• Tests - tumour markers, imaging studies, bloods tests/bone marrow biopsy (if haematologic malignancy)
• Treatment - surgery, chemotherapy, radiotherapy

Behavioural

• Examples - e.g. non compliance, self harm, psychiatric illness, unhealthy lifestyle, poor biomechanics
  Treatment - education, counseling, physical therapy, community supports +/- psychotherapy or psychotropic drugs

Congenital

• Examples - birth malformations, genetic disorders, inborn errors of metabolism
• Time course - chronic (but may have acute complications)
• Treatment - see also Physical trauma, Endocrine, Metabolic

Degenerative

• Examples - MSS 'wear and tear', accelerated aging of cells
• Time course - chronic (but may have acute complications)
• Tests - imaging studies, functional studies

Remember to remove and address the inciting cause and resultant complications