Neuro Review

Question 1

What is bacterial meningitis?

Answer 1

Inflammation of meninges secondary to bacterial infection

Question 2

Causes of bacterial meningitis

Answer 2

Hemorrhagic spread, foreign body migration, extension of otitis media/interna (majority of cases), traumatic or iatrogenic inoculation

Question 3

Diagnosis of bacterial meningitis

Answer 3

Clinical presentation, routine blood work, MRI (meningeal contrast enhancement), CSF (marked neutrophilic pleocytosis with intracellular bacteria, can be normal in chronic cases, only 33% bacterial growth), pyrexia only in 13% of cases

Question 4

Prognosis of bacterial meningitis

Answer 4

Good prognosis (83% survival to discharge), with few/mild long-term neurological deficits.

Question 5

Decerebrate

Answer 5

Extensor rigidity in all 4 limbs, patient comatose.
Severe midbrain lesion.
Poor to grave prognosis.

Question 6

Decerebellate

Answer 6

Opisthotnus, flexed pelvic limbs.
Acute cerebellar lesion.
Better prognosis than decerebrate.

Question 7

Menace

Answer 7

Afferent: ipsilateral CNII, contralateral thalamus and occipital cortex

Efferent: contralateral motor cortex, ipsilateral cerebellum, ipsilateral CN VII

Question 8

PLR

Answer 8

Midbrain

Afferent: CN II

Efferent: CN III parasympathetic

Question 9

Trigeminofacial reflex

Answer 9

Palpebral, vibraase, lip pinch
PONS

Afferent: CN V

Efferent: CN VII

Question 10

Corneal reflex

Answer 10

PONS

Afferent: CN V (ophthalmic branch)

Efferent: CN VII (globe retraction, CN VII (Blink))

Question 11

Physiologic nystagmus

Answer 11

PONS, midbrain

Afferent: CN VIII

Efferent: CN III, IV, VI

Question 12

Gag reflex

Answer 12

Medulla

Afferent: CN IX, X

Efferent: CN IX, X, XII

Question 13

Reactive Seizure

Answer 13

The normal brain’s natural response to a transient disturbance in function, usually metabolic or toxic in nature. Is usually reversable when the inciting cause is removed or corrected (i.e. hypoglycemia)

Question 14

Epileptic Seizure

Answer 14

A manifestation of excessive synchronous epileptic activity of neurons in the brain.

Question 15

Epilepsy

Answer 15

Recurrent seizures of at least two unprovoked epileptic seizures (of any type) in a 24-hour period, resulting from a disease in the brain causing a predisposition to generate epileptic seizures.

Question 16

Cluster seizure

Answer 16

Two or more seizures within a 24-hour Period

Question 17

Status Epilepticus

Answer 17

Continuous seizures or two or more discrete seizures between which there is incomplete recovery of consciousness, lasting at least 5 minutes. A neurologic emergency requiring immediate therapy

Question 18

Focal seizure

Answer 18

Seizures that originate from a focus in one cerebral hemisphere and usually manifest localized or regional clinical signs, which may include involuntary or compulsive actions such as chewing, licking, and defensive or aggressive behavior.

Question 19

How does status epilepticus cause neuronal necrosis?

Answer 19

In late SE, Cerebral blood flow decreased simultaneously as blood pressure decreases and cerebral metabolic rate (i.e. glucose and oxygen use) increases. This leads to ATP depletion and lactate accumulation.

Question 20

Progressive intracranial diseases

Answer 20

1. Inflammation (Granulomatous Meningoencephalitis)
2. Nutritional Alterations (Thiamine Deficiency)
3. Infection, Anomalous ( Hydrocephalus)
4. Trauma
5. Neoplasia

Question 22

Normal intracranial pressure?

Answer 22

5-12 mmHg

Question 23

Causes of increased ICP

Answer 23

TBI, Intracranial mass, inflammatory encephalopathy, status epilepticus, obstructive hydrocephalus, infectious/non-infectious causes

Question 24

Cushing’s triad

Answer 24

-bradycardia
-hypertension
-irregular breathing

Question 25

Chemical autoregulation of ICP

Answer 25

1. PaCO2
   - inc CO2 –> inc H+ ions –> stim cerebral vasodilation
   - dec H+ –> vasoconstriction
2. PaO2
   - dec PaO2 –> vasodilation –> inc CBF, CBV, ICP
3. CMRO2
   - in high metabolic regions, pH alterations in perivasc space influence vasc tone
   - inc H+ (lactic acidosis, other acids) –> inc CBF

Question 26

Hypertonic saline

Answer 26

-reduces cerebral water content
-reduces blood viscosity -> improved cerebral perfusion
-beneficial effects on excitatory NTs as well on immune system
-Does not get reabsorbed in the kidneys so less likelihood of causing hypotension than mannitol

Question 27

Mannitol

Answer 27

-Immediate plasma expanding effect, which reduced blood viscosity -> increases CBF
-Delayed osmotic effect occurs 15-30 min after administration, lasts 1-3 hours
-Free scavenging properties

Question 28

Functions of CNS

Answer 28

1. provide mechanical protection for brain by making it buoyant and reducing effective weight
2. acid-base regulation
3. intracerebral transport for AAs and sugars
4. protects brain physically by buffering increases in ICP by translocating to extracranial space

Question 29

Explain the pathophysiology of the Cushing’s reflex

Answer 29

-Intracranial hypertension leads to decreased cerebral blood flow, cerebral ischemia, and accumulation of CO2
-Decreased CBF and increased CO2 stimulates the release of catecholamines which causes systemic vasoconstriction and increased CO
-Baroreceptors sense hypertensive state -> vagally mediated bradycardia