Exam 4 Flashcards
Guillain-Barre´ Syndrome
Prototype: Acute Inflammatory demylinating polyradiculoneuropathy (ADIP)
Post infectious polyneuropathy
Ascending symmetrical paralysis (over 12 days- 4weeks)
Acute , rapidly progressing and potentially fatal form
Guillain-Barre´ Syndrome incidence
more in males, 1.8 per 100,000
Guillain-Barre´ Syndrome etiology
Unknown cause but involves cellular and humoral immune system. Development of IgG antibodies
Thought to be an autoimmune response to antibodies formed in response to a recent pathological event.
Guillain-Barre´ Syndrome patho
T cells migrate to the peripheral nerves resulting in edema and inflammation, macrophages invade the area and break down the myelin
More inflammation around the demyelinated areas cause further dysfunction
Once the temporary inflammatory response halts the myelin regenerates.
If there is damage to the axon itself, residual neurologic dysfunction may occur.
Myelin in Guillain-Barre´ Syndrome
- Loss of myelin, edema and inflammation of nerves
- Immune system overreacts to the infection and destroys the myelin sheath
- As myelin is lost
- Nerve impulse transmission slows down or is totally lost
- Muscles denervate and atrophy
- In recovery nerves re-myelinate
- Nerve function returns slowly in a proximal to distal pattern.
Triggering events for Guillain-Barre´ Syndrome
- Campylobacter jejuni gastroenteritis= 30% of cases.
- viral infection 1-3 weeks prior to onset (usually involving the upper resp tract)
- Bacterial infections
- Vaccines
- Lymphoma
- Surgery and Trauma
Clinical Manifestations of Guillain-Barre´ Syndrome
Weakness of lower extremities (hours to days to weeks), Paresthesia, Paralysis
Hypotonia – reduced muscle tone, Areflexia
ANS dysfunction: orthostatic hypotension, hypertension, abnormal vagal response (heart block, bradycardia), bowel and bladder dysfunction, flushing, diaphoresis, SIADH,
Cranial Nerve involvement: facial weakness, EOM difficulties, dysphasia and paresthesia of the face
Respiratory Failure – may require intubation and ventilation
Pain- no sensory neurons are effected
CSF may reveal elevated protein level
Diagnostic studies for GB
History and Physical Initial CSF normal with low protein. After 7-10 days protein increases Electromyography (EMG) and nerve conduction test show reduced nerve conduction Brain MRI done to rule out MS
Treatments for GB
Plasmapheresis- the removal of plasma and components that may be contributing to disease states. (removal of antigen and antibody complexes)
Administration of immunoglobulin (Sandoglobin)
Rehabilitation
Factors that influence ICP
Arterial and venous pressure Intraabdominal and intrathoracic pressure Posture Temperature Blood gases (CO2 levels)
Monro-Kellie doctrine
If one component increases, another must decrease to maintain ICP.
Normal ICP
5 to 15 mm Hg
Elevated if >20 mm Hg sustained
To decrease brain volume
remove mass, decrease cerebral edema- bone flap, osmotic diuretic (mannitol, 3% hypertonic saline)
To decrease blood volume
Correct obstruction of venous outflow (Head midline)
Normal CO2 levels (CO2 levels = vasoconstriction = cerebral blood volume = ischemia)
To decrease CSF
drain it (external ventricular drain)
Cerebral blood flow definition
The amount of blood in milliliters passing through 100 g of brain tissue in 1 minute
About 50 mL/min per 100 g of brain tissue
Cerebral blood flow autoregulation
Adjusts diameter of blood vessels
Ensures consistent CBF
Only effective if mean arterial pressure (MAP) 70 to 150 mm Hg
Cerebral perfusion pressure
CPP = MAP – ICP
Normal is 60 to 100 mm Hg. (less than 30 incompatable with life)
<50 mm Hg is associated with ischemia and neuronal death.
Effect of cerebral vascular resistance- CPP = Flow x Resistance
cerebral blood flow pressure changes
Compliance is the expandability of the brain.
Impacts effect of volume change on pressure
Compliance = Volume/Pressure
Stages of Increased ICP
Stage 1:total compensation
Stage 2: ↓compensation; risk for ↑ICP
Stage 3: failing compensation; clinical manifestations of ↑ICP (Cushing’s triad)
Stage 4: Herniation imminent → death
Factors affecting cerebral blood vessel tone
CO2
O2
Hydrogen ion concentration
Cushings triad
Hypertension, bradycardia, irregular RR= Herniation
Types of cerebral edema
vasogenic, cytotoxic, interstitial
Vasogenic cerebral edema
Most common type Occurs mainly in white matter Fluid leaks from intravascular to extravascular space. Variety of causes Continuum of symptoms → coma
Cytotoxic Cerebral Edema
Disruption of cell membrane integrity
Secondary to destructive lesions or trauma to brain tissue
Fluid shift from extracellular to intracellular
Interstitial Cerebral Edema
Usually result of hydrocephalus
Excess CSP production, obstruction of flow, or inability to reabsorb
Treat with ventriculostomy or shunt
Decrease motor function with increase ICP
Hemiparesis/hemiplegia Decerebrate posturing (extensor)- Indicates more serious damage Decorticate posturing (flexor)
Tentorial herniation
Tentorial herniation (central herniation) occurs when a mass lesion in the cerebrum forces the brain to herniate downward through the opening created by the brainstem.
Uncal herniation
with lateral and downward herniation.
Cingulate herniation
with lateral displacement of brain tissue beneath the falx cerebri.
Diagnostics for ICP
CT scan / MRI / PET
EEG
Cerebral angiography
ICP and brain tissue oxygenation measurement (LICOX catheter)
Doppler and evoked potential studies
NO lumbar puncture- cerebral herniation could occur from the sudden release of the pressure in the skull from the area above the lumbar puncture.
Ventriculostomy
Catheter inserted into lateral ventricle (used to drain)
Coupled with an external transducer (wave forms of brain) measures ICP
Fiberoptic catheter
Sensor transducer located within the catheter tip, measures ICP
Subarachnoid bolt or screw
Between arachnoid membrane and cerebral cortex, measures ICP
Inaccurate readings of ICP caused by
CSF leaks Obstruction in catheter/ kinks in tubing Differences in height of bolt/transducer Incorrect height of drainage system Bubbles/air in tubing
LICOX catheter
Measures brain oxygenation (PbtO2) and temperature.
Placed in healthy white brain matter.
Jugular venous bulb catheter
Measures jugular venous oxygen saturation (SjvO2).
Drug therapy for ICP
Corticosteroids (Vasogenic edema) Antiseizure medications Antipyretics Sedatives Analgesics Barbiturates
Nutrition for increased ICP
Hypermetabolic and hypercatabolic state ↑ need for glucose
Enteral or parenteral nutrition
Early feeding (within 3 days of injury)
Keep patient normovolemic.
IV 0.9% NaCl preferred over D5W or 0.45% NaCl
Interventions to optimize ICP and CPP
HOB elevated appropriately Prevent extreme neck flexion. Turn slowly. Avoid coughing, straining, Valsalva. Avoid hip flexion.
spinal cord
Approximately 45 cm (18 inches) long
Thickness comparable to finger
Extends from foramen magnum at base of skull to lower border of first lumbar vertebrae where it tapers to fibrous bands
Nerve roots extend below 2nd lumbar space
Mechanism of Spinal Injury
Flexion Hyperextension Flexion-rotation Extension-rotation Compression
Flexion injury
occur when the head is suddenly & forcefully accelerated forward, causing extreme flexion of the neck.
occurs in head-on collisions & diving accidents.
typically seen in the C5-6 area of the cervical spine
Hyperextension injury
are frequently acceleration injuries as are seen in rear-end collisions or as the result of falls in which the chin is forcibly struck.
C4-5 is the area of the spine most commonly affected.
Compression injury
(Axial loading) cause the vertebra to squash or burst.
They usually involve high velocity and affect both the cervical and thoracolumbar regions of the spine.
Blows to the top of the head and forceful landing on the feet or buttocks can result in compression injury.
Rotation injuries
caused by extreme lateral flexion or twisting of the head & neck.
The tearing of ligaments can easily result in dislocation as well as fracture, & soft tissue damage frequently complicates the primary injury.
Extent of neurologic damage caused by spinal cord injury results from
Primary injury damage
-Actual physical disruption of axons
Secondary damage
-Ischemia, hypoxia, microhemorrhage, and edema
Because secondary injury processes occur over time, the extent of injury and prognosis for recovery are most accurately determined 72 hours or longer after injury.
Secondary injury
Hypo-perfusion Decreased Circulation Decreased Blood Flow Vasospasm Demyelinated Axons
Complete injury
Results in a total loss of sensory/ motor function below the level of injury.
Complete dissection of the spinal cord and its neurochemical pathways.
Paraplegia Tetraplegia
Paraplegia
paralysis of the lower portion of the body, sometimes involving the lower trunk. Injury occurs in the thoracolumbar region (T2 to L1).
Tetraplegia
(formerly called quadriplegia) impaired function of the arms, trunk, legs, and pelvic organs. Injury occurs from the C1 to T1 level.
Incomplete injury
Some function remains below the level of injury.
Syndromes Associated with incomplete lesions
Central cord syndrome Anterior Cord Syndrome Posterior cord Syndrome Brown – Sequard Syndrome Conus Medullaris Syndrome and Cauda Equina Syndrome.
Central cord syndrome-
damage primarily to the central gray or white matter of the spinal cord.
Results from edema formation that occurs in response to the primary injury.
The resulting motor deficit is more severe in the upper extremities than in the lower.
The sensory impairment is variable. Improvement over time is expected.
Anterior Cord Syndrome
typically results from injury or infarction involving the anterior spinal artery, which perfuses the anterior two thirds of the spinal cord.
The resultant damage includes motor paralysis with loss of pain & temperature sensation noted below the level of the lesion.
Still have touch and vibration sense
Posterior Cord Syndrome
extremely rare syndrome in which proprioreceptive sensation of position and vibration are lost due to damage to the posterior columns of the spinal cord.
Brown-Sequard Syndrome
results from a unilateral injury, usually of the penetrating type, that involves just half of the spinal cord.
There is a resulting loss of motor ability plus touch, pressure, and vibration sensation on the same side as the injury but loss of pain and temperature sensation on the opposite side.
Conus Medullaris Syndrome and Cauda Equina Syndrome
Damage to the very lowest portion of the spinal cord (conus) and the lumbar sacral nerve roots (cauda equina).
Results in flaccid paralyisi of the lower limbs and areflexic (flaccid) bladder and bowel.
Level of injury (segments)
Upper cervical (C1-C2) Lower cervical (C3-C8) Thoracic (T1-T12) Lumbar (L1-L5) Sacral (S1-S5)
Autonomic Nervous System Syndromes
Spinal Shock Neurogenic Shock (warm/ brady)
Spinal Shock
- This is the temporary suppression of reflexes below the level of injury
- SCI interrupts stimulation that keeps neurons ready.
- Over time spinal neurons gradually regain excitability, which ends spinal shock. (hours to weeks)
- has long-term effects on sensation and voluntary movement
- Functions controlled by spinal reflex arcs do not depend on communication with the brain, & the impact on these functions is limited to spinal shock.
Neurogenic Shock
- Pts with severe cervical and upper thoracic injuries.
- hemodynamic instability caused by the loss of innervation from the brain to the SNS.
- The loss of sympathetic outflow allows the PNS to be engaged unopposed.
- The parasympathetic influence results in hypotension from peripheral vasodilation, severe bradycardia, & hypothermia.
Autonomic Dysreflexia
Massive, uncompensated cardiovascular reaction
Exaggerated sympathetic response
Seen after Spinal Shock (above T6)
Triggered by Distended bladder or bowel or Pressure ulcers
INCREASED BP (300 sys), Severe headache, Increased sweating, Decreased HR, Cool skin below injury, flushing, blurred vision, & nasal congestion
If injury to C5 or higher
may need to be intubated in field
Be aware of potential Bradycardia
May need atropine
Diagnostic test for spinal cord injury
Standard x-rays- can demonstrate fracture or dislocation of the vertebral bodies or spinal processes
Computed tomography (CT)- used to further evaluate areas of the spine that may be injured but cannot be adequately visualized on standard x-ray
Magnetic resonance imaging (MRI)- MRI shows bone poorly but provides excellent visualization of the spinal cord and nerve roots. Identify contusion or hemmorhage
Medications for Spinal cord injury
methylprednisolone (Solu-Medrol)- within 8hrs or not at all
Corticosteroids- to decrease edema of the cord
Vasopressors- to treat bradycardia or hypotension due to spinal shock
Antispasmodics- to treat spasticity
Analgesics- to reduce pain
Histamine H2 antagonists- to prevent stress-related gastric ulcers