Wednesday, March 28, 2012

Neurologic diseases review

Basic Concepts in Normal Neurologic Function

 Oxygen supply:  The brain requires 20% of the O2 in the body
  • Glucose supply:  The brain requires 65 to 70% of the glucose in the body
  • Blood supply:  The brain requires 1/3 of the cardiac output
  • Acid-base balance

1.      Cerebral vasodilation
2.      CNS depressant    ® coma

1.      Cerebral vasocontriction
2.      CNS stimulant     ®  seizures

§        Blood-brain barrier:  Protects the brain from certain drugs, chemicals and microorganism.  It a layer of least semi-permeable capillaries
§        CSF volume:  CSF cushions the brain; it nourishes the brain and determines the ICP.  The choroids plexus in the lateral ventricles primarily produces CSF.  The normal CSF volume is 100 to 150 mls at a time, an average of 120 mls.

Neurologic Assessment

 1.  Mental Status
  • Orientation to three spheres :  people, time and place
  • Memory:  Immediate recall, recent memory, remote memory
a.       Immediate recall:  Ask the client to repeat your question
b.      Recent memory:  Ask client about recent events that occurred few minutes, few hours
c.       Remote memory:  Ask the client about events in the remote past, or historical events that can be answered by the general population

2.  Level of consciousness (LOC)
-         It is the most sensitive indicator of the changes in the neurologic status of the client
-         The center for wakefulness is the ascending reticular activating system ARAS/reticular formation

-         Assess both wakefulness and content of thought
-         Levels of consciousness:
§         Level I- conscious, coherent, cognitive (3 Cs)
§         Level II- confused, drowsy,  lethargic, obtunded, somnolent
§         Level III- stuporous; responds only to noxious, strong or intense stimuli. e.g.  sternal pressure, trapezius pinch, pressure at the base of the nail or supraorbital area, very strong light or very loud sound
§         Level IV
1.  Light coma; response is only by grimace or withdrawing limb from pain; primitve and disorganized response to painful stimuli

2.  Deep Coma; absence of response to even the most painful stimuli

 GLASGOW COMA SCALE (GCS) is an objective measure to describe LOC.  It is based on the client’s response in three areas :  eye opening, motor response, verbal response

Normal 8-15; 7 or less indicates coma

    1. Best eye-opening response
a.  Spontaneously                                                           = 4
b.  To speech                                                                 = 3
c.  To painful stimuli                                                        = 2
d.  No opening                                                                = 1

    1. Best Motor Response
a. Obeys verbal command                                       = 6
b.      Localizes painful stimuli                                     = 5
c. Flexion: withdrawal to pain                                   = 4
d.      Flexion: abnormal (decorticate                          = 3
e. Extension:abonormal(decerebrate)                       =2
f.  No response to pain on any limb                          = 1

      3. Best Verbal Response
                    a.  Oriented to time, place, person                             = 5
                     b. Engages in conversation, confused in content        = 4
                     c.  Words spoken but conversation not sustained      = 3
                     d.  Groans on evoked pain                                       = 2
                     e.  No response                                                                   = 1

                                                             CVA, Stroke
1.  Anterior cerebral stroke: lower extr emity more involved than upper extremity,
contralateral hemiparesis and sensory deficits
2.  Posterior cerebral stroke: contralateral sensory loss, transient contralateral

Middle cerebral artery stroke: upper extremity more involved than the lower
extremity, contralateral sensory loss

Risk Factors
1. Diabetes
2.   Atherosclerosis
3.   Hypertension
4. Cardiac disease
5.  Transient ischemic attacks

Aneurysm Precautions
1.  Avoid rectal temperatures
2. Limit visitors
3.  Avoid Valsalva’s maneuver
4.  Head of bed should be between 30-45 degrees
Valsalva’s maneuver – occurs when attempting to forcibly exhale with the glottis,
mouth and nose closed.  It causes an increase in intrathoracic pressure with an
accompanying collapse of the vein of the chest wall. The following may result:
1.  Slowing of the pulse
2.  Decreased return of blood to the heart
3.  Increased intrathoracic pressure

Elevated Intracranial Pressure
In most cases you should do the following:
1.  Maintain proper fluid volumes
2.  Set-up quiet environment for minimal sensory stimulation
3.  Elevate HOB (head of bed) to approximately 30 degrees
4.  Limit suctioning performed

Horner’s Syndrome
- Sympathetic innervation to the face is interrupted by a lesion
in the brain stem resulting in pupillary constriction, dry and red face with no
sweat, ptosis-Mueller’s muscle, problem located in sympathetic ascending fibers
Autonomic Dysreflexia
- caused by a lesion in the high thoracic or cervical cord.
Severe hypertension, sweating and headaches noted.  May occur with a
blockage in a urine catheter

Parkinson’s Disease
-a degenerative disease with pr imary involvement of the
basal ganglia; characterized by the following:
1. Bradykinesia
2. Resting tremor
3.  Impaired postural reflexes
4. Rigidity
5.  Loss of inhibitory dopamine
6.  Mask like affect
7. Emotional lability

Multiple Sclerosis
–progressive demyelinating disease of the central nervous
system affecting mostly young adults
Cause unknown, most likely viral.
1. Fluctuating exacerbations
2. Demyelinating lesions limit neural transmission
3.  Confirmed with lumbar puncture, elevated gamma globulin, CT/MRI,
myelogram, EEG.
4.  Mild to moderate impaired cognition common
5. Sensory Deficits
6. Bowel and Bladder Deficits
7. Spasticity common
8. Ataxic gait

Myasthenia gravis
- neuromuscular disease characterized by fatigue of skeletal
muscles and muscular weakness.
Key point
-Review the differentiation between MG and a cholinergic crisis, using
the Tensilon Test. A cholinergic crisis may have hypotension, bradycardia vs.
myasthenia gravis.
1. Progressive involvement
2. Decreased muscle membrane acetylcholine receptors
3.  Severe weakness (proximal more than distal muscles)
4.  Facial, ocular and bulbar weakness
5. Possible life-threatening respiratory muscle weakness
6.  Probable use of anticholinesterase drugs for treatment

Guillain-Barre’ Syndrome
-polyneuropathy with progressive muscular weakness
1.  Demyelination of peripheral and cranial nerves
2.  Motor paralysis in an ascending pattern
3.  3% Mortality – respiratory failure
4. Autonomic dysfunction-arrhythmias, blood pressure changes, tachycardia

Amyotrophic lateral sclerosis
(Lou Gehrig’s disease) – degenerative disease
affecting upper and lower motor neurons
1.  Death typically in 2-5 yrs.
2. Spasticity, hyperreflexia
3. Dysarthria, Dysphagia
4.  Autonomic Dysfunction in approximately 1/3 of patients
5.  Cognition is normal
Post-polio Syndrome
- slowly progressive muscle weakness that occurs in
patients with a history of acute poliomyelitis, after a stable period
1. New Weakness
2. Pain/Myalgia
3. Abnormal fatigue
Epilepsy-recurrent seizures due to excessive and sudden discharge of cerebral
cortical neurons.
Tonic-clonic (Grand Mal) –Pt. confused and drowsy about the seizures, 2-5 min
Absence seizures  (Petit Mal)- Brief, no convulsive contractions, may be up to
100X day
Simple Seizures- no loss of consciousness
Complex Seizures, brief loss of consciousness with psychomotor changes
Key Point
- When a patient has a seizure during most interventions, do not use
a tongue blade and allow free movement in a safe environment
Meningitis-inflammation of the meninges of the spinal cord and brain caused by
The most common bacteria are the following:
Neisseria meningitidis, Diploc occus
Haemophilus influenzae

1.  Brudzinski’s sign
2.  Kernig’s sign
3. Stiff/Tight neck
4. Fever
5. Confused
Anterior Cord Syndrome – damage is mainly in anterior cord resulting in loss of
motor function and pain and temperature with preservation of light touch,
proprioception and position sense
Brown-Sequard Syndrome – hemisection of SC resulting in ipsilateral weakness
and loss of position and vibration sense below the level of lesion

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