CNS Metabolic Disorders

Question 1

What pattern of injury would you see with anoxic-ischemic encephalopathy of the cortex?

What area of ischemia would result in “man in the barrel syndrome?”

Answer 1

Laminar necrosis - deeper cortical layers 3, 4, and 5 more vulnerable to injury

Watershed infarcts (ACA-MCA regions)

Question 2

How does presentation with hypoglycemia compare with that of anoxia/ischemia?

Answer 2

Will also see laminar necrosis since brain requires both glucose and oxygen for energy metabolism.

Question 3

Clinical features of someone with hypocalcemia? Hypercalcemia?

Answer 3

Hypo –> Neuromuscular hyperexcitability with positive Trousseau sign and Chvostek’s sign

Hyper –> depressed DTRs

Question 4

Clinical manifestations of hepatic encephalopathy?

Associated drugs?

Answer 4

Elevated brain ammonia

Acute liver failure –> decreased glutamate reuptake –> astrocytes swell –> edema, hyperexcitability, seizures

Acetominophen

Question 5

Thiamine B1

Site of absorption
Sites vulnerable to deficiency?
Symptoms of Wernicke’s encephalopathy?

Answer 5

Duodenum

Mammillary bodies, thalamus, hypothalamus, brainstem –> would see recurrent petechial hemorrhages

Ophthalmoplegia, ataxia, and confusion

Question 6

Vitamin B12 deficiency

Clinical features
Pathophysiology for neurological problems?

Answer 6

Macrocytic anemia

Subacute combined degeneration –> demyelination of dorsal and lateral columns–> ataxia, LE numbness/tinging, rapid spastic LE weaknes

Question 7

Carbon monoxide poisoning

Molecular mechanism
Imaging
Characteristic findings
Treatment

Answer 7

Carbon monoxide with HIGH affinity to Hgb (> O2) –> carboxyhemoglobin –> hypoxia

Discrete lesions to GP, sometimes putamen

Cherry red appearance to skin

Treat with hyperbaric oxygen

Question 8

Where do radiation lesions usually localize in the CNS?

Answer 8

Lesions of coagulative necrosis and adjacent edema typically in white matter.

Question 9

Symptoms of following chemotherapies:

Cytarabine
Methotrexate
Ifosfamide

Answer 9

Cytarabine - acute onset cerebellar ataxia, seizures, dementia, coma

Methotrexate - drowsiness, ataxia, confusion–higher risk with radiotherapy

Ifosfamide - decreated glutathione in CNS

Question 10

How does one get tetrodotoxin poisoning? Mechanism of action? Symptoms?

Answer 10

INHIBITS Na+ Channels

Perioral paresthesias that spreads from face to limbs
Respiratory distress and arrhythmias

Question 11

Saxitoxin mechanism? Symptoms?

Answer 11

Paralytic shellfish poisoning

INHIBITS Na+ channel

Paresthesia of mouth/oral mucosa that can develop within 30 minutes ingestion

SUPPORTIVE treatment–death from respiratory failure

Question 12

Brevetoxin mechanism? Symptoms?

Answer 12

Persistent activation of inward Na+

Paresthesia of mouth/oral mucosa
Temperature reversal–SIMILAR TO CIGUATOXIN

Question 13

Ciguatoxin

Answer 13

Get from carnivorous fish species like bass, snapper, barracuda

Agonist of voltage dependent Na+ channels

Temperature reversal!