Unit 4: Nervous, endocrine and sensory pathology
Basic Cellular Pathology notes · PTU syllabus (BMLS401-18)
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Unit summary
The nervous, endocrine and sense organ systems have their own diseases. This unit covers neuronal damage, raised intracranial pressure, cerebral infarction, head injury, Alzheimer's disease and dementia, disorders of the pituitary, thyroid, adrenal and pancreas, otitis and cataract.
After this unit you can
- Describe neuronal damage, raised intracranial pressure and stroke
- Describe head injury and dementia
- Describe pituitary, thyroid, adrenal and pancreatic disorders
- Describe otitis and cataract
PTU syllabus topics
- Neuronal damage
- raised intracranial pressure
- cerebral infarction
- head injury
- Alzheimer's disease
- dementia
- pituitary
- thyroid (goitre)
- adrenal (Cushing's, Addison's) and pancreatic (diabetes) disorders
- otitis and cataract
Diabetes mellitus
Insulin deficiency or resistance
Fasting glucose ≥ 126 mg/dL; HbA1c ≥ 6.5%
Hypothyroidism
Low T3, T4
High TSH (primary)
Cushing's syndrome
Excess cortisol
High cortisol, loss of daily rhythm
Addison's disease
Low cortisol and aldosterone
Low sodium, high potassium
Topic 1
Neuronal damage and raised intracranial pressure
- Neuronal injury: hypoxia, toxins, trauma and infections; neurons cannot divide, so loss is permanent; repair is by glial scarring (gliosis).
- Raised intracranial pressure: tumours, bleeding, oedema, hydrocephalus, meningitis; headache, vomiting, papilloedema; risk of brain herniation. Lumbar puncture is avoided until raised pressure is excluded.
Appearance
Turbid
Clear (TB: clear with cobweb clot)
Cells
Many neutrophils
Lymphocytes
Protein
High
Mildly raised (TB: high)
Glucose
Low
Normal (TB: low)
Topic 2
Cerebral infarction and head injury
- Stroke: ischaemic (thrombosis or embolism → infarction; most common) or haemorrhagic (hypertension). Risk factors as for atherosclerosis; sudden weakness, speech loss.
- Head injury: concussion, contusion, extradural haematoma (artery — lucid interval), subdural haematoma (veins — elderly), skull fractures with CSF leak.
Topic 3
Alzheimer's disease and dementia
- Dementia: progressive decline in memory and thinking. Alzheimer's disease (commonest) shows amyloid plaques and neurofibrillary tangles with brain atrophy. Other causes: vascular dementia, B12 deficiency and hypothyroidism (treatable — tested in the lab).
Topic 4
Endocrine disorders
Pituitary: gigantism and acromegaly
Excess growth hormone (adenoma)
High GH, IGF-1
Pituitary: dwarfism, diabetes insipidus
GH or ADH deficiency
Low GH; dilute urine
Thyroid: goitre
Iodine deficiency, Graves', Hashimoto's
TSH, T3, T4, thyroid antibodies
Hyperthyroidism
Graves' disease
Low TSH, high T3 and T4
Hypothyroidism
Hashimoto's, iodine deficiency; cretinism in infants
High TSH, low T4; neonatal TSH screening
Cushing's syndrome
Excess cortisol (steroids, tumours)
High cortisol, high glucose, low K
Addison's disease
Adrenal destruction
Low cortisol, low Na, high K
Diabetes mellitus
Insulin deficiency or resistance
Glucose, HbA1c, urine ketones
Topic 5
Otitis and cataract
- Otitis media: middle ear infection, common in children (S. pneumoniae, H. influenzae); pus culture if discharging. Otitis externa: ear canal infection (Pseudomonas, fungi).
- Cataract: opacity of the lens — ageing, diabetes, galactosaemia, steroids; treated surgically.
Key terms
- Intracranial pressure
- Pressure within the skull
- Infarction
- Tissue death due to loss of blood supply
- Neurofibrillary tangles
- Abnormal tau protein in Alzheimer's neurons
- Goitre
- Enlargement of the thyroid gland
- Cataract
- Opacity of the eye lens
Quick revision
- Neuronal injury; raised ICP; CSF patterns in meningitis.
- Ischaemic vs haemorrhagic stroke; head injury types.
- Alzheimer's pathology; treatable dementias.
- GH, thyroid, adrenal, pancreatic disorders and lab tests.
- Otitis media and externa; cataract causes.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.State three signs of raised intracranial pressure.
- Q2.Give the CSF findings of bacterial meningitis.
- Q3.What is a lucid interval?
- Q4.Name two treatable causes of dementia.
- Q5.Give thyroid test results in hypothyroidism.
- Q6.Name two causes of cataract.
Long-answer questions
- Q1.Describe raised intracranial pressure and CSF findings in meningitis.
- Q2.Describe stroke and head injury.
- Q3.Describe disorders of the thyroid and adrenal glands.
- Q4.Describe dementia and Alzheimer's disease.
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