Download peripheral nervous system - Stritch School of Medicine

Case 1
 A 71 year old male presents for progressive difficulty walking
 Developed back pain several weeks ago
 Reports numbness in his legs
 Has been having increasing difficulty walking
 Physical Examination
 Vitals stable
 Normal cranial nerve findings
 Increased tone of the LE bilaterally with moderate LE weakness;
UE’s normal
 LE reflexes are brisk with upgoing toes; UE reflexes normal
 Reduced sensation to all modalities to mid-abdomen
 Gait slow with a spastic quality & requiring assistance
Case 1
 Can you localize the lesion?
Localization
Peripheral nervous
system
Central nervous system
 Brain
 Spinal cord

Nerve root

Plexus

Peripheral nerve

Neuromuscular junction

Muscle
The most important step in neurologic
localization is differentiating a central
nervous system lesion from a peripheral
nervous system lesion
4
Localization
Upper motor neuron
 Mildly reduced bulk
 Increased tone
 Mild/moderate weakness
 Hyper-reflexia & pathologic
responses
Grading muscle power
5: Full strength
4: Movement against some resistance
3: Movement against gravity only
2: Movement with gravity eliminated
1: Flicker or trace contraction
0: No contraction
5
Lower motor neuron
 Severely reduced bulk with
fasciculations
 Reduced tone
 Severe weakness
 Hypotonia
Grading reflexes
4: Hyper with pathologic
responses
3: Hyperactive
2: Normal
1: Diminished
0: Absent
Localization
 Spinal levels
C5/6
Its easy to
remember…1/2, 3/4,
5/6, 7/8
C7/8
ALWAYS ABNORMAL:
L3/4
 Asymmetric reflexes
Pathologic responses
(Babinski, clonus = CNS)
Absent reflexes (PNS)
S1/2
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Case 1
 1. What studies do you want to order and why?
Where does
the spinal cord
end?
Spinal Cord Compression
Management
 Dexamethasone (100 mg
IV followed by 16 mg PO
daily in divided doses)
Differential
Metastatic disease
Epidural hematoma
Epidural abscess
 Surgical evaluation
 Radiotherapy
Vertebral collapse (2’ malignancy)
Aortic dissection
Case 2
 28 year old male presents for progressive difficulty walking
 “Stomach flu” 2 weeks ago
 Recently developed low back pain and paresthesias in his feet
 Has been having difficulty standing, climbing stairs, and has been
tripping frequently
 Physical Examination
 Vitals stable
 Cranial nerves normal
 Tone is relatively reduced; There is mild weakness of bilateral ankle
dorsiflexion with normal muscle bulk
 Distal sensation is reduced to all modalities but normal in the trunk
 Reflexes are reduced throughout
 There is a mild bilateral foot drop
Case 2
 Can you localize the lesion?
Localization
Peripheral nervous
system
Central nervous system
 Brain
 Spinal cord

Nerve root

Plexus

Peripheral nerve

Neuromuscular junction

Muscle
The most important step in neurologic
localization is differentiating a central
nervous system lesion from a peripheral
nervous system lesion
13
Localization
REFLEX ARC
Case 2
 1. What studies do you want to order and why?
 What else do you need to get the above done?
Test Results
CSF Analysis
EMG/NCV
 WBC 2
 RBC 0
 Protein 103 (15-45)
 Glucose 50
 Coags and platelets WNL
Conduction block
Guillain-Barre Syndrome
Clinical Features
 Typically follows an
infectious process (2/3rds
of pts)
 C. jejuni, CMV, EBV, M.
pneumoniae
 Presents with numbness
& tingling in the feet that
ascends
 Pain the back & limbs is
common
 Weakness follows
sensory disturbances
 Areflexia
 Bowel & bladder are
usually spared
 Autonomic dysfunction
 Symptoms should not
proceed >8 weeks
 98% of pts achieve
“plateau phase” by 4 weeks
 Duration of “plateau” 12
days
17
Guillain-Barré syndrome
 Ancillary studies
 Albuminocytological dissociation with elevated CSF
protein with no or a few mononuclear cells
 May be normal in the first week
 If WBC count >10 think about Lyme, HIV, sarcoidosis
 Antiganglioside antibodies
 GM1 Abs (correlate with C. jejuni infection)
 GQ1b associated with C. Miller Fisher variant (ataxia, areflexia &
ophthalmoparesis)
 Electrophysiologic data (EMG/NCV)
 Temporal dispersion, prolonged F-wave latencies, conduction
block & demyelinating range slowing
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Guillain-Barré syndrome: Subtypes
 Miller-Fisher variant
 AIDP
 Most common type
 AMAN
 10%-20% of caseprogressive
weakness often with respiratory s
 Rapidly failure
 DTRs can be preserved or
exaggerated!
 Ataxia, areflexia,
ophthalmoplegia
 GQ1b Abs in almost all
patients
 Pure sensory
 Pure dysautonomic
 CV involvement is the most
common
 75% positive for C. jejuni (vs. 42%
in AIDP)
 GM1, GD1a, GD1b Abs
 Pharyngeal-brachial-cervical
 GT1a Abs
 May mimic MG
 AMSAN
 Possibly the most severe form
with slow and/or incomplete
recovery
 Paraparetic
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Treatment
 IVIG (0.4g/kg/day for 5 days) is at least effective
as plasma exchange without some side effects
 Should be started within 2 weeks
 Inconclusive data that IVIg has a higher relapse rate
 Corticosteroids have not been shown to be
beneficial
 Intubation criteria:
 VC <15-20 mL/kg (oe <30% baseline)
 PO2<70 mmHg
 Oropharyngeal weakness
20
GBS vs ATM
Case 1
 A 27 year old female presents to the ER by her husband for
“sudden onset of confusion”
 The patient is not following commands and is not talking
 Physical Examination
 She was unable to answer any questions, follow commands,
repeat, or produce spontaneous language
 She had right lower facial weakness
 She had right arm weakness
 She had decreased sensation over her right arm and face
Case 3
 Can you localize the
lesion?
 Central nervous system,
left hemisphere
 The patient has right
sided weakness and
aphasia, which is highly
suggestive of a left
hemispheric stroke.
Questions
 What helps differentiate cortical from subcortical?
 Cortical lesions can be associated with multimodal motor and
sensory deficits, such as aphasia and apraxia
 White matter lesions (subcortical lesions) usually cause
weakness, spasticity, pure motor syndromes…but not aphasia,
apraxia, etc.
Stroke: Subcortical strokes
 Caused by occlusion of small
(0.5-15.0 mm) penetrating
branches of cerebral arteries
 Chronic HTN>DM>emboli
Syndrome Presentation Localization
Pure Motor
Face, arm, leg
Internal capsule
Pure Sensory
Face, arm, leg
Thalamus
Sensorimotor
Face, arm, leg
Thalamocapsular
Ataxichemiparesis
Hemi-ataxia &
hemiparesis
Basis pontis
Clumsy hand
dysarthria
Dysathria,
incoordination
Genu of the IC
25
Acute stroke syndrome



A-B-C’s
 NPO, intubate for inadequate
airway, ventilate if needed
 Correct hypotension, rule out
acute MI or arrhythmia (a-fib)

IV tPA must be/may be given within
4.5 hrs of stroke onset

Neuro deficit (NIHSS score 5 to 22)
must not be rapidly improving (TIA)
or post-ictal
Rule out hypoglycemia

Blood glucose is between 50 and
400 mg/dl

Normal PTT, PT<15 sec, platelets
>100,000

Minimize hyperglycemia by running
an IV of 0.9% normal saline initially
at a TKO rate

No bleeding, recent surgery, MI,
arterial puncture or LP

No blood, or edema/infarct > 1/3 of
MCA territory on CT
Use parenteral antihypertensive Tx
only for sustained, very high BP
(>220/120; or >185/110 for IV tPA)

BP maintained under 185/110
TIME IS BRAIN!!!
Clinical History
 What imaging test do you want to order?
 CT scan
 in deteriorating patient, quickly rules out hemorrhage, mass
(tumor, abscess) or early infarct edema
 shows cortical infarcts by 1-2 days, may miss lacunar infarcts
 MRI scan
 highest resolution scan, but longer scanning time
 DWI (diffusion weighted imaging) detects impaired movement of
water in infarct immediately
 non-invasively view arterial supply (MRA)
 contraindications: pacemaker
Non Infused Head CT
Non Infused Head CT
 What is your impression of the head CT?
 The CT shows loss of gray-white junction and effacement of the sulci
throughout the left hemisphere, suggestive of a stroke
Evaluation
 Based on the patient’s history, physical exam findings, and
CT scan, she was taken to Interventional Radiology for a
cerebral angiogram…
Cerebral Angiogram
Angiogram
MCA
occlusion
Clinical History
 The patient received intra-arterial t-PA. Following the
procedure, she was transferred to the Neuro-ICU for
observation and management. A follow-up MRI was
obtained later…
MRI (Diffusion Weighted Image)
Questions
 What do you think this patient’s long-term outcome was?
 The patient presented within 3 hours of the onset of
symptoms. She received intra-arterial t-PA which was
effective in breaking the clot and re-establishing flow to the
left hemisphere. She was speaking English by the end of the
day…and French (her second language) the next day.
Because her symptoms were recognized quickly and action
was taken, her injury was limited.
Cerebral Angiogram Post t-PA
Pre tPA
Post tPA
Question
 By the time everything was done, it was 4:15 in the
afternoon on a Friday. You have time to order one test
that might change your management that night….what
would you order (ie, what would you be looking for that
would have caused her stroke?)
Question
 Answer….
 Lower extremity venous doppler to look for the presence of a
deep vein thrombosis (some people would argue for an
echo…)
 The patient was found to have a DVT and received an IVC
filter.
 How did a blood clot in her leg get into her left middle
cerebral artery?
 She had a patent foramen ovale (upwards of 30% of the
population do)
Case 4
 A 34 year old female presents to the ER with complaint of eyelid
drooping
 Started about one weak ago following an ER; she was given
steroids for an asthma exacerbation and ciprofloxacin for an
asymptomatic UTI
 Has felt “weak all over” and has been getting progressively short of
breath
 Physical Examination
 Speech is soft with a nasal quality
 There is fluctuating bilateral ptosis, pupils are equal and reactive,
she has a “snarl” smile
 Normal bulk/tone; strength can be overcome after <60s of effort
 Normal reflexes, normal sensory examination
 Gait normal, but cannot stand up 10 times consecutively
Case 4
 Can you localize the lesion
Peripheral NS
 The PNS generally includes
 The nerve cell bodies
 The peripheral nerves
 Roots
 Plexus
 Nerve
 The neuromuscular
junctions (NMJs)
 The muscles
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Localization
NMJ
 Fluctuating weakness
(pre- and post-synaptic)
 Normal bulk and tone
 Normal sensory exam
 Normal reflexes (usually)
Case 2
 How do you want to evaluate the patient?
 Studies to Order/Perform
 Diagnostic
 Ice Pack Test
 Improves ptosis 2° MG in 80%
 Local cooling slows kinetics of AChRs
 Sleep Test
 Tensilon Test
 Respiratory Studies!!!
 BMP w/ Mg/Phos, PT/PTT, ionized calcium
 May need Quinton catheter placed by IR
Case 2
 Studies
 EMG/NCS with
repetitive stimulation or
single fiber EMG
 Chest CT
 Those who undergo
thymectomy are more
likely to have clinical
improvement, become
asymptomatic or attain
remission
 May be less effective in
those >60
 Labs
 AChRAb
 85% of pts w/ gMG and
50-60% w/ oMG test
positive
 MuSK antibody
 Striational muscle Ab
 Screen for TSH, RA,
Pernicious anemia, SLE,
Sarcoid, Sjogren’s,
polymyositis
Case 2
 Admit to ICU
 Any pt w/ MG w/ questionable respiratory status should be
admitted to the ICU for close monitoring
 14% of pts in myasthenic crisis have some degree of arrhythmias
 Respiratory
 30% of pts develop respiratory muscle weakness and crisis occurs
in 15-20%
 Intubation Criteria/Management:
 VC < 15 mL/kg
 Stop anti-cholinesterase medication (causes excessive bronchial
secretions and diarrhea)
 If needed, give pyridostigmine IV at 1/30th the oral dose
Case 2
 Acute Treatment
 TPE
 Produces impvt in 75% of pts
 Long term medication
 Pyridostigmine 15-60 mg Q3-6
 Long acting 180mg
 Pts w/ primarily ocular symptoms respond poorly
 Corticosteroids
 10-20 mg/daily initially
 Increase by 5-10 per week until satisfactory clinical response or dose
of 50-60/day
 Azathioprine
 2-3 mg/kg initially (most start w/ 50 mg/d for 1 week)
Case 5
 A 32 year-old woman is found on the floor at work,
unconscious, but spontaneously breathing.
 Physical Examination
 BP is 146/75, pulse 80, afebrile.
 There is complete left lid ptosis. Her left pupil is 5 mm and
sluggishly reacts to light; the right pupil is 2 mm and briskly
reacts to light.
 She does not grimace or move to painful stimuli, nor attempt
to speak.
Case 5
 Can you localize the lesion?
Evaluating the Altered Patient
 1. What does the
patient look like?




Old?
How many lines?
Noisy neighbor?
Jerry Springer is blasting
away and they are
tangled in their call light?
 Like you need to call the
unit?
Evaluating the Patient
 2. Talk to the patient
 Can they stay awake and pay attention to you?
 Can the patient talk to you?
 How do they sound (abnormal rate, dysarthric…)
 Are they making any sense?
 Can they tell you where they are?
 Patients are first disoriented to time of day, then other aspects of
time, and then to place
 Disorientation to self is rare…like raise the red flag rare
Evaluating the Patient
 3. Ask them to read and write
 Decreased reading comprehension is characteristic of
delirium
 Writing disturbance is the most sensitive language
abnormality in delirium
 The most salient characteristics are abnormalities in the
mechanics of writing…the formation of letters and words is
indistinct, and words and sentences sprawl in different
directions
Evaluating the Patient
 4. How does his/her breathing look?
 Does it look like he/she is breathing comfortably and
can protect the airway?
 What does the breathing pattern look like?
 Rule of thumb: if breath sounds can be heard at both
lung bases and if the RR is >8/min, ventilation is
probably adequate
 Quick FVC: How high can they count with one breath (counting
to 20 is roughly equal to 2 L)
 ABG is the only certain method of determining adequate
ventilation
Evaluating the Patient
 5. What do the eyes look like?
 The eyes are your biggest friend in an emergency
 When examining pupils, make sure the lights are off and the
room is as dark as possible
 Use a bright light
 If there are abnormalities, ask to look at a drivers license or
other photo or ask family members (is it old or new?)
Evaluating the Patient: The Eyes
 1. Observe for blinking at rest, to light, to threat, or loud
sound
 2. Observe the position of the eyelids
 Lift and release the lids, noting the tone
 In unconscious pts the eyelids close gradually after they are released, a
mvt that can not be duplicated voluntarily by a hysterical patient
 3. Observe the position of the eyes
 A light held 50 cm from the face should reflect from the same point on
each pupil if the eyes lie on conjugate axes
 4. Test for corneal reflex (if the patient is not easily
arousable)
 Should cause bilateral response of eyelid closure and upward
deviation of the eye (Bell’s phenomenon)
Evaluating the Patient
 6. Observe the size of the pupils and reactivity to
light
 The presence or absence of the light reflex is the single
most important physical sign potentially distinguishing
structural from metabolic coma
 Pupillary pathways are relatively resistant to metabolic
insult; midbrain lesion destroy it
 Both anatomic innervations (sym and parasymp)
are tonically active, and the resting pupil
represents a balance
 Unopposed parasymp pupil: 1.5-2 mm
 Unopposed symp pupil: 8-9 mm
Coma: pupil size and reactivity
 Smaller, reactive pupils
persist in metabolic coma
 Larger, unreactive
pupil(s) reflect third
cranial nerve or midbrain
lesion
 Pinpoint, reactive pupils
from pontine lesion (or
narcotic overdose)
 Medicinal eyedrops may
impair light reflex
Evaluating the Patient
 7. Examine for the Oculocephalic reflex (“Doll’s Head Eye
Phenomenon”)
 Hold the eyelids open and briskly rotate the head from one
side to the other, at least briefly holding the endpoints
 Positive response: contraversive conjugate eye deviation (head
to the right, eyes to the left)
 Briskly flexed and then extended
 Positive response: deviation of the eyes opposite; the eyelids
may open reflexly (dolls head phenomenon)
Evaluating the Patient
 8. Cold calorics (oculovestibular reflex)
 Can be very helpful in evaluating for brain death
 Not useful in an acute setting as it is time consuming and
somewhat cumbersome
Evaluating the Patient
 9. Examine the motor
function
 What is the tone (normal,
flaccid rigid)
 What is the strength (if the
patient can cooperate) or
response to pain
 Apply nailbed pressure or
other noxious stimuli
 Normal response:
pushing the stimulus
away, quick and nonstereotyped withdrawal
of the limb, or mvt of the
body and limb away from
the stimulus
Evaluating the Patient
 10. Check the Reflexes
 Have a reflex hammer (even skilled examiners cannot elicit
reflexes with a stethescope)
 Reflexes should be symmetric
 Upgoing toes/pathologic reflexes always indicate some CNS
dysfunction
Case 5
 What test do you want to order for this patient?
Subarachnoid hemorrhage
 Berry aneurysm
commonest if no trauma
 Verify blood by CT, or LP
if CT normal
 Emergent angio and
surgical or interventional
management
Intubate if GCS <8 or hypoxemia
IV Fluids (2L 0.9% NS)
MAP ≤120 mm Hg and systolic <180
mg Hg
Nimodipine 60 mg 6xs/daily
Phenytoin (if seizures occur)
EVD for acute hydrocephalus