9. Unconsciousness due to metabolic origin

Question 1

Unconciousness due to metabolic origin is usually a disorder of?

Answer 1

Awareness

Question 2

General symptoms of unconciousness due to metabolic origin

Answer 2

• Pupils are normal size, reactive to light
• Depressed mental state
• Confusion
• Depressed respiratory rate
• Symmetrical reduced limb movements, hypotonic
• Hemiparesis can occur

Question 3

Metabolic causes of unconciousness

Answer 3

• Hypoglycemia
• DKA
• Vit B1 def. (wernick encephalopathy)
• Deficiency of essential substrates (glucose, oxygen, vit B12)
• Exogenous toxins (drugs, metals, solvents)
• Endogenous toxins/ststemic metabolic disease (uremia, hepatic encephalopathy, electrolytes, thyroid storm)

Question 4

Metabolic diseases causing unconciousness

Answer 4

• Prolonged hypoglycemia
• Hyperosmolar hyperglycemia
• Diabetic ketoacidosis
• Hypoxia
• Hypercapnia
• Hypothermia
• Renal/uremic encephalopathy
• Hepatic encephalopathy
• Electrolyte imbalance (hyper- hyponatremia, hyper- hypocalcemia etc.)

Question 5

Prolonged hypoglycemia (in regards of unconcioussness)

Answer 5

Etiology: insulin overdose, fasting, alcohol
Clinical: usually light reflex present
Patho: does not produce focal necrosis in the brain, brainstem or SC, but necrosis in hippocampus, caudate nucleus and dentate gyrus. Superficial layers of cortex are damaged.
under 0,6 mmol/L bl. glc can cause coma

Question 6

Hyperglycemia (in regards of unconciousness)

Answer 6

• Hyperosmolar hyperglycemia: involuntary movements, seizures and hemipareses. Mild/absent ketoacidosis
• DKA: often precipitated by infection or poor medical compliance. Progressive neurological impairments with lethargy and coma
• Dehydration, fatigue, weakness, headache, abd. pain, kussmal breathing, confusion, coma

Question 7

Causes of hypoxia

Answer 7

• Reduced arterial ox. pressure: lung disease, PE
• Reduced hemoglobin: anemia, blood loss
• Reduced flow of O2 rich blood: reduced CO, reduced cerebral flow
• High altitudes

Question 8

Signs of hypoxia in regards to unconciousness

Answer 8

• Lung disease, PE: confusion and lethargy, then followed by unconcioussness
• Conciousness is lost in a few seconds if PO2 drops to under 40 mmHg
• Hypoxic hypoxia (wo. ischemia) can be tolerated for 10-40 min wo. permanent brain damage, even if PO2 is under 20 mmHg
• Grey matter more vulnerable than white (frontal cortex, hippocampus esp. vulnerable)
• Pupils large-reactive
• No eye movements

Question 9

Causes of hepatic encephalopathy

Answer 9

Severe liver damage. Increased ammonia, abnormal fatty acid metabolism, free radicals, cerebral edema

Question 10

Symptoms of hepatic encephalopathy

Answer 10

Pupils: small-reactive
No eye movements
Increased RR
Asterixis, myoclonus, ataxia, hyperreflexia, Hemipareses
Unconciousness, coma in severe stages.
Abnormal EEG