Neurology and Clinical Chemistry Flashcards
What are neurological causes of coma?
- Cerebral infarction, hemorrhage
- Space occupying lesion/tumour, abscess, hematoma
➔ trauma - Infections — meningitis, encephalitis
➔ epilepsy
What are the metabolic causes of coma?
- DM
- Hypoglycemia
- Renal failure
- Liver failure
What are the endocrine causes of coma?
- Hypopituitary coma
- Adrenal insufficiency
- Myxoedema coma
- Parathyroid abnormalities
What is CSF exam used for?
Blood in CSF suggests subarachnoid hemorrhage
- Look for xanthochromia due to:
1. oxyHb
2. methemoglobin
3. bilirbin last 2-3 weeks
A lot of intact RBCs in CSF exam suggest…
Traumatic tap — needle inadvertently entered an epidural vein during insertion
What is indicator of brain injury?
- CK-BB in CSF
- Serum S100B
What is the most common cause of acute bacterial meningitis? Symptoms?
Meningococcal meningitis
Symptoms
- Headache
- Stiff neck
- Fever
- Coma and death
What are the lab investigations for bacterial meningitis? What are the CSF findings in bacterial meningitis?
Culture & gram stain
CSF Findings
1. high PMN
2. low glucose — need for glucose as fuel by infiltrating immune cells in response to infection
3. high lactate — lactate produced by bacterial anaerobic metabolism
What are the two types of diabetic coma?
- DKA
- Glucose > 20 mmol/L
- high ketones
- low pH — metabolic acidosis - Hyperosmolar non-ketotic diabetic coma:
- glucose > 40 mmol/L
- normal ketones
- low pH — lactic acidosis, secondary to dehydration
low blood volume
- hypoglycaemic coma
What are the clinical symptoms of acute intermittent porphyria?
Abdominal pain
Vomiting
Weight loss
What confirms acute intermittent porphyria?
ALA & PBG in urine
What are the symptoms of Guillain Barre Syndrome and CIDP and how to test for it?
Symptoms
- Generalized paralysis due to Ab destruction of myelin sheath
- Ascending paralysis
Test ➔ rule out hypo/hyperkalemia
- elevated protein in CSF
- normal WBC
What are examples of chronic and acute inflammatory neuropathies?
Chronic
➔ IgG4 Nodal/Paranodal Abs
➔ MGUS — IgM anti-MAG
➔ Multifocal Motor Neuropathy (MMN) — IgM + GM1/GM2 gangliosides
Acute
➔ GBS — IgG GD1 alp/beta, GM1 alp/beta & GT1 alpha ganglioside
What are the toxins and drugs that may cause peripheral neuropathy?
- Arsenic
- Pb
- Organophosphates
- Tricyclic antidepressants
- Dilantin
What can metabolic neuropathy be caused by?
- Alcohol — Vit B1 deficiency
- Vit B12 deficiency
- Diabetic neuropathy
- Uremia
- Myeloma
What are 3 lab investigations for peripheral neuropathy?
- Hematological studies
- Serum
- Protein electrophoresis
How to classify intellectual disability (ID) or mental retardation?
IQ — 90-109 (50% of population)
➔ <90 (25% of population)
➔ <70 (1.8% of population) — mild ID
➔ <50 (0.4% of population) — severe ID
What are the leading causes intellectual disability? (In decreasing order)
- Indeterminate (genetic?)
- Perinatal disorders
- Chromosome abnormalities
What are some examples of congenital disorders? (decreasing order of frequency)
- Spina bifida
- Down’s
- Sex chromosomal disorder
What are examples of perinatal disorders of extracerebral origin?
- Hypoxia & ischemia
- Cerebral palsy
- Hypoglycemia
What are causes of intellectual disability in neonates and infants?
- Fetal alcohol syndrome
- Prematurity
- Heavy metal poisoning (Pb)
What are some causes and investigations of dementia?
- Alzheimer’s ➔ beta amyloid and tau protein
- Hypothyroidism ➔ thyroid function test
- Nutritional deficiency ➔ Vit B12
- Creutzfeldt Jacob disease ➔ proten 14-3-3 for prion disease
How much CSF is formed? How is it formed? How is it sampled?
- 500 mL formed/day
- Ultrafiltrate of plasma formed in choroid plexus
- Sampled by lumbar puncture
What is the difference between CSF and plasma?
- Lower total protein
➔ lower proportion of high MW proteins (lower IgG:albumin ratio)
➔ contains CSF specific transferrin also called tau protein, beta and gamma trace protein
➔ contains prominent prealbumin band - Lower glucose
- Low cell count
