A9. Unconsciousness due to metabolic origin

Question 1

Unconsciousness due to metabolic origin is usually a disorder of

Answer 1

disorder of awareness

Question 2

Unconsciousness due to metabolic origin can manifest as

Answer 2

persistent vegetative state (PVS),
also called unresponsive wakefulness syndrome (from lecture).

Question 3

General symptoms of Unconsciousness due to metabolic origin

Answer 3

• pupils are normal in size and reactive to light
• eye movements are usually full and conjugate
• depressed mental state
• confusion with impairment of consciousness
• depressed respiratory rate
• limb movements are symmetrically reduced and associated with hypotonicity.
• Hemiparesis can occur in:
  *non-ketotic hyperosmolar coma, *hepatic encephalopathy.
  *hyperglycemic encephalopathy.
  *uremic encephalopathy.

Question 4

Causes of Unconsciousness due to metabolic origin

Answer 4

● Deficiency of essential substrates (glucose, oxygen, vitamin B12)

● Exogenous toxins
(eg. drugs, heavy metals, solvents)

● Endogenous toxins/systemic metabolic diseases
(eg. uremia, hepatic encephalopathy, electrolyte imbalances, thyroid storm

Question 5

Deficiency of essential substrates that can cause Unconsciousness due to metabolic origin

Answer 5

• glucose
• oxygen
• vitamin B12

Question 6

Exogenous toxins that can cause Unconsciousness due to metabolic origin

Answer 6

• drugs,
• heavy metals,
• solvents)

Question 7

example of Endogenous toxins/systemic metabolic diseases which cause Unconsciousness due to metabolic origin

Answer 7

• uremia,
• hepatic encephalopathy,
• electrolyte imbalances,
• thyroid storm

Question 8

causes of Disorder of glucose metabolism (prolonged hypoglycemia)

Answer 8

Can be due to
* insulin overdose,
* fasting,
* alcohol intoxication and
* rarely insulinomas

Question 9

how to differentiate between comatose state due to hypoglycemia
and a structural cause.

Answer 9

In hypoglycemia, pupillary light reactions may be intact, while in structural damage they
are usually absent

Question 10

does hypoglycemia lead to focal necrosis in brain, brainstem or spinal cord?

Answer 10

Hypoglycemia does NOT cause focal necrosis in brain, brainstem or spinal cord.
They remain intact even in long-standing, severe hypoglycemia

Question 11

In Disorder of glucose metabolism (prolonged hypoglycemia) what is damaged

Answer 11

The superficial layers of the cortex are damaged,
but laminar necrosis (as in global ischemia) is NOT seen

Question 12

Disorder of glucose metabolism (prolonged hypoglycemia - where does necrosis occur

Answer 12

Necrosis also develops in the
* superficial layers of the cortex
* hippocampus,
* caudate nucleus and
* granular cells of dentate gyrus

Question 13

what blood glucose level can cause coma?

Answer 13

Blood glucose levels <0,6 mmol/l can cause coma

Question 14

Hyperosmolar hyperglycemia results from

Answer 14

hyperosmolar effect of severe hyperglycemia

Question 15

Hyperosmolar hyperglycemia can cause patient to have

Answer 15

involuntary movements,
seizures and
hemiparesis

Question 16

is vascular thrombosis common in Hyperosmolar hyperglycemia

Answer 16

not uncommon

Question 17

does ketoacidosis occur in Hyperosmolar hyperglycemia

Answer 17

Ketoacidosis is mild or does not occur

Question 18

Diabetic ketoacidosis occurs in patient with

Answer 18

known diabetes, but can also be the first manifestation

Question 19

Diabetic ketoacidosis is often precipitated by

Answer 19

infection
or
poor medical compliance

Question 20

Diabetic ketoacidosis - what metabolites are accumulated

Answer 20

accumulation of acetone and ketone bodies

Question 21

patients with Diabetic ketoacidosis present with

Answer 21

• progressive neurological impairment
• with lethargy, and
• ultimately coma

Question 22

Symptoms of diabetic ketoacidosis

Answer 22

• dehydration (due to osmotic diuresis),
• fatigue,
• weakness,
• headache,
• abdominal pain,
• Kussmal breathing,
• confusion,
• coma

Question 23

causes of Hypoxia

Answer 23

• May also occur at high altitudes (low O 2 tension of the atmosphere and in drowning

○ Reduced arterial oxygen pressure: e.g. lung disease or PE
■ Hypoxia due to PE causes confusion and lethargy before loss of consciousness

○ Reduced hemoglobin to carry oxygen: anemia or blood loss
19
■ pO 2 does not drop, but substrate availability is decreased or O 2 fails to bind to
hemoglobin

○ Reduced flow of blood containing O 2 (ischemic hypoxia): due to reduced cardiac output
→ reduced cerebral blood flow

○ Biochemical block of cerebral utilization of O 2 : e.g. cyanide poisoning (rare), also called
histotoxic hypoxia

Question 24

causes of Reduced arterial oxygen pressure:

Answer 24

1. lung disease
2. or PE
   ■ Hypoxia due to PE causes confusion and lethargy before loss of consciousness

Question 25

causes of **Reduced hemoglobin to carry oxygen**:

Answer 25

1. anemia or 2. blood loss ■ pO2 does NOT drop, but substrate availability is decreased or O2 fails to bind to hemoglobin

Question 26

cause of **Reduced flow of blood containing O 2 (ischemic hypoxia)**:

Answer 26

due to reduced cardiac output → reduced cerebral blood flow

Question 27

causes of **Biochemical block of cerebral utilization of O 2**

Answer 27

* cyanide poisoning (rare), also called histotoxic hypoxia

Question 28

Hypoxia due to PE causes confusion and lethargy before what?

Answer 28

loss of consciousness

Question 29

if pO 2 drops under 40 mmHg

Answer 29

Consciousness is lost in some seconds

Question 30

how long can Hypoxic hypoxia (without ischemia) be tolerated without permanent damage

Answer 30

can be tolerated for 10-40 minutes without permanent damage to the brain, even if pO 2 is below 20 mmHg

Question 31

CO intoxication leads to

Answer 31

bilateral necrosis of globus pallidus

Question 32

is grey matter or white more vulnerable to hypoxia list structure most vulnerable

Answer 32

**grey matter is more vulnerable** than white Vulnerability to hypoxia (most to least), ○ **Frontal cortex** (most) ○ **Hippocampus, parietal/occipital cortex** ○ **Basal ganglia/cerebellum** ○ **Brain stem**

Question 33

Symptoms of hypoxia - pupil and eye

Answer 33

Pupils: large-reactive Eye movements: no movement – conjugate (if severe)

Question 34

Hypercapnia symptoms

Answer 34

* headache, * confusion, * disorientation, * involuntary movements, * papilledema, * depressed limb reflexes, * extensor plantar response

Question 35

if PCO2 > 50 mmhg in COPD or obesity-ventilation syndrome

Answer 35

**CO2 narcosis** may occur

Question 36

when does co2 narcosis occur in COPD or obesity-ventilation syndrome?

Answer 36

if pco2 over 50 mmhg

Question 37

Hypothermia Common in

Answer 37

* alcoholics with Wernicke encephalopathy (deficiency of B1)

Question 38

Renal/uremic encephalopathy is a sign of

Answer 38

acute renal failure

Question 39

what happens in Renal/uremic encephalopathy

Answer 39

* Brain amino acid metabolism is also impaired, and * causes an imbalance between excitatory and inhibitory neurotransmitters or * accumulation of false neurotransmitters

Question 40

Renal/uremic encephalopathy EEG shows

Answer 40

Slow waves are found on the EEG

Question 41

can Renal/uremic encephalopathy be reversed?

Answer 41

condition is reversed with dialysis, but may take 1-2 days before it is totally reversed

Question 42

Hepatic encephalopathy onset can be

Answer 42

Can have acute or chronic onset

Question 43

causes of hepatic encephalopathy

Answer 43

* increased ammonia, * false neurotransmitters, * endogenous benzodiazepine-like structures, * abnormal fatty acid metabolism, * free radical damage, * cerebral edema and * increased mercaptans

Question 44

Symptoms of Hepatic encephalopathy

Answer 44

○ Pupils: small-reactive ○ Eye movements: no movement – dysconjugate (if severe) ○ Increased respiratory rate ○ Asterixis, myoclonus, dysarthria, ataxia, hyperreflexia, hemiparesis

Question 45

how does patient with hepatic encephalopathy appear in early phase vs late

Answer 45

* At earlier phases the patient is in an agitated confusional state * Unconsciousness and coma are the most severe stages.

Question 46

Hepatic encephalopathy- Neurological signs in comatose patients include

Answer 46

* hemiparesis, * ocular bobbing, * dysconjugate eye movements and * tonic downward deviation of the eyes

Question 47

In deep coma what can be present | hepatic encephalopathy

Answer 47

* decerebrate posture and * agonal respiration can be present

Question 48

Hepatic encephalopathy EEG shows

Answer 48

The EEG is always abnormal (shows triphasic slow waves)

Question 49

Electrolyte disturbances

Answer 49

● Hypernatremia ● Hyponatremia ● Hypercalcemia, ● hypocalcemia, ● hyperkalemia ● hypokalemia ● hypomagnesemia,

Question 50

Hypernatremia present as

Answer 50

Hyperosmolar diabetic hypernatremia: mostly in elderly diabetic patients

Question 51

what does hypernatremia cause to the brain

Answer 51

○ Leads to osmotic dehydration of the brain

Question 52

Hyponatremia range

Answer 52

Na <126 mmol/l

Question 53

Hyponatremia causes

Answer 53

* primary renal disease, * osmotic diuresis, * adrenal insufficiency, * vomiting, * diarrhea, * burns, * ascites, * peritonitis, * edema, * dilution, * sickle cell syndrome, * hyperglycemia, * SIADH

Question 54

Hyponatremia treatment

Answer 54

slow correction of the sodium, over several days ○ Too fast correction can cause central pontine myelinolysis (symptoms can be vertical gaze palsy, tetraplegia)

Question 55

○ Too fast correction of hyponatremia can cause

Answer 55

**central pontine myelinolysis** (symptoms can be: vertical gaze palsy, tetraplegia)

Question 56

**central pontine myelinolysis** symptoms

Answer 56

* vertical gaze palsy, * tetraplegia)

Question 57

which electrolyte disturbances Can cause coma in severe cases

Answer 57

* Hypercalcemia, * hypocalcemia, * hypomagnesemia, * hypokalemia, * hyperkalemia * hypernatremia * hyponatremia

Question 58

Other causes of Unconsciousness due to metabolic origin

Answer 58

● Hypothyroidism ● Lactic acidosis ● Addison’s disease