Download Peripheral Nerve clinical cases

Bell's Palsy
An otherwise healthy 23-year-old male presents with right sided facial weakness and numbness
since last night. He does not seem too concerned but his mother is worried that he might be
having a stroke. The nurse finds you to see the patient right away. What is your first step in
evaluation of this patient? The patient has forehead involvement (weakness) and normal eye
movements (no lack of forehead involvement nor lack of ability to abduct an eye to suggest
abducens nucleus involvement - CVA). His exam shows incomplete eye closure on the affected
side. What other areas of exam should you pay attention to? Make sure no ear infection or
mastoiditis. Look for evidence for Ramsay Hunt syndrome, vesicular rash, which is herpes
zoster needing valcyclovir. Look for this rash on tip of nose (Hutchinson’s sign) indicating
branch of nerve which could also have ophthalmic involvement needing opthalmology consult.
What is your plan? Plan should include home w reassurance, clinic f/u, eye patch for sleeping,
eye lubrication, prednisone 1 mg/kg/day x 7d. Antivirals aren’t helpful per most sources.
Guillain-Barre Syndrome
36-year-old Hispanic woman who presented to the outpatient clinic with complaints of
numbness, tingling, and weakness in her legs. The patient was initially seen in the clinic 3
weeks ago with upper respiratory tract infection and was treated with a course of amoxicillin.
Her upper respiratory symptoms improved, but a week later she noticed numbness and tingling
in her feet, progressively ascending to her legs and thighs. She was evaluated in the ED, and
her diagnostic work-up included blood cultures and LP.The emergency physician consulted the
neurologist, but the patient left ED against medical advice. The numbness became
progressively worse, and she started having bilateral lower extremity weakness and gait issues.
She fell 2 days ago, and her family forced her to seek medical help. Her past medical history is
unremarkable except for the upper respiratory infection (URI) 3 weeks ago. The patient's review
of systems was negative for shortness of breath, fever, chilis, cough, and swallowing difficulties.
Her vital signs were temperature 37°C, pulse 112/minute, blood pressure 108/62, respiration 28/
minute, weight 162 lbs, height 5’2". What do you want to pay particular attention to on
exam? On neurological examination, the patient was alert and oriented X 3, with intact speech,
comprehension, and memory; pupils equal round reactive to light. Dysmetria was noted for
finger-to-nose and rapid alternating movements bilaterally. Her cranial nerve exam was intact.
Her motor strength in triceps, biceps, and supinator were 5/5; deltoids and pronator were 4/5;
wrist extensors and flexors were 4/5 bilaterally; hip flexors, quadriceps, and hamstrings
were 4/5 bilaterally; dorsiflexors and plantar flexors were 3/5 bilaterally. Her sensation was intact
on upper extremities but diminished to touch and pin prick on lower extremities and abdomen.
Her gait was ataxic, deep tendon reflex (DTR) 1 + and symmetrical on deltoid, biceps, brachioradialis and triceps; DTR was absent on knees and ankles. What is your workup? The
patient's laboratory studies did not reveal any infectious process. Her cerebrospinal fluid (CSF)
studies reveal an elevated protein count of 200 mg/dL, with normal cell count, which supports
the diagnosis of GBS. What is your plan? The disease can progress rapidly and can be
potentially fatal if treatment interventions are delayed. Neurology consulted and the patient was
admitted to the intensive care unit. Why the ICU? What can you assess need for intubation
at the bedside? tongue weakness and/or extensor neck strength can be assessed and used
as a marker for the eventual need for mechanical ventilation. What treatment interventions
might be started in the ICU? IVIG or plasmapheresis. No steroids - could be harmful.
Myasthenia Gravis
A 68-year-old woman presents to the emergency department of an outside hospital with
dyspnea for one week. She denies a cough, sputum, chest pain or other respiratory symptoms.
She also denies symptoms of upper and lower extremity weakness, blurred vision or swallowing
difficulty. Sixteen years previously, she was diagnosed with diabetes mellitus, hypertension and
depression. Eleven years ago, she underwent total thyroidectomy for a papillary thyroid
carcinoma. The patient is taking selective serotonin reuptake inhibitor, zolpidem, alprazolam and
methylphenidate for insomnia and depression, levothyroxin and alfacalcidol for thyroid disease,
a calcium channel blocker for hypertension, and sulfonylurea and metformin for type 2 diabetes
mellitus.
What is your Ddx for dyspnea?
What next? Examine the patient:
On the initial physical examination, the patient is not in acute respiratory distress. The vital signs
are normal: blood pressure is 170/90 mmHg, pulse rate is 92 beats/min, respiratory rate is 24
breaths/min, and body temperature is 36℃. The mental status is intact, the patient is alert but
ptosis and mild dysarthria are noted, otherwise the neurological examinations of cerebral
function, cerebellar function and both extremities are normal. Pretibial pitting edema and neck
vein engorgement are absent. On the chest auscultation, there are mild crackles at both lower
lung fields. The body mass index is 24.2 kg/m2.
What has changed with your Ddx now?
What next? Labs and imaging
The laboratory evaluation shows a white blood cell count of 6,580/µL, hemoglobin of 12.0 g/dL
and platelet count of 325,000/µL. Other blood chemistries are within normal limits: BUN/Cr
12.2/0.9 mg/dL, AST/ALT 25/25 units/L, NT-proBNP 107.2 pg/mL, and glucose 92 mg/dL.
Thyroid function testing showed: T3 0.73 ng/mL, FT4 1.71 ng/dL and TSH < 0.003 µIU/mL. The
arterial blood gas analysis, on room air, was pH 7.441, PaCO2 39.9 mmHg, PaO2 64.7 mmHg,
oxygen saturation 93.2%, and D(A-a)O2 36.
The initial chest X-ray only shows a slightly reduced lung volume. The chest computed
tomography (CT) scan showed no evidence of pulmonary thromboembolism, but there is
bibasilar atelectasis. Echocardiography revealed normal systolic and diastolic heart function.
During the next five days inpatient at the outside, rural hospital, her dyspnea has become more
severe and the rural hospitalist called HCMC for transfer. Today, on the sixth day of
hospitalization, the patient has mild to moderate respiratory distress with labored breathing. The
respiratory rate is 29 breaths/min and the mental status is generally normal. Neuro exam shows
alert, but ptosis and moderate dysarthria. The arterial blood gas analysis on an O2 mask with
10 L was pH 7.324, PaCO2 54.9 mmHg, PaO2 94.4 mmHg, and oxygen saturation 96.6%. The
chest X-ray revealed no definite infiltration but the lung volume was reduced (Fig. 1B).
What additional diagnostic test could you perform? consider the edrophonium test or ice
bag test.
Edrophonium increases the acetylcholine in the synapse by blocking acetylcholinesterase. The
edrophonium test indicates myasthenia gravis is the etiology of a patient’s weakness if their
symptoms improve after the edrophonium is given. Dosing must be deliberately cautious since,
in patients who have weakness from other causes, edrophonium can cause profound worsening
of weakness and respiratory failure. Typical dosing to start (a test dose) is 1 to 2mg, waiting 30
to 90 seconds to assess response. If there is no adverse response and also no dramatic
improvement, 3mg can be tried. If still no response after 30 to 90 seconds, 5mg can be given –
maximum total dose through all these administrations is 10mg. An alternative is the ice bag
test, which shows improvement in ptosis after ice is held on the patient’s eye. The ice bag test
is 80% sensitive and is positive when the ptosis improves by 2mm after 2 minutes.
The patient now has severe respiratory distress with labored breathing. The respiratory rate is
40 breaths/min and the mental status shows confusion.
Now what do you do?
The patient is intubated, ventilated and transferred to the intensive care unit. Neurology
consulted and plan for plasmapheresis. Plasmaphersis therapy consists of filtering antibody
proteins out of the blood, thereby removing the offending anti-AChR antibodies. Intravenous
immune globulin (IVIG) is second line acute therapy.
A single fiber EMG looks for increased "jitter," which is variability in the time of neuromuscular
transmission measured in a single muscle fiber. The test has a sensitivity of up to 95% is
systemic, and 84% in ocular MG, making it the single most sensitive test for this disorder.
Botulism
A 55-year-old male presents by ambulance from home, once day after a family reunion with
nausea, vomiting, diarrhea and abdominal pain since yesterday. Now today he’s developed
double/blurred vision with dilated, unreactive pupils, slurred speech and difficulty with
swallowing. He exhibits mild ptosis bilaterally. Arms and legs have normal strength. He is alert,
not confused. He has no fever. What additional questions would you ask? What did you
eat at the family reunion? He says that he ate: homemade salsa, baked potatoes sealed in
aluminium foil, cheese sauce, sauteed onions under a layer of butter, garlic in oil, salted fish,
fermented fish, Jalapeno peppers and potato salad. He denies eating any honey.
I thought botulism was from honey and only in infants, what gives?
Foodborne botulism — The onset of symptoms in foodborne botulism usually begins within 12
to 36 hours after ingestion of a preformed toxin, but the incubation period may range from
several hours to one week. Prodromal symptoms often include nausea, vomiting, abdominal
pain, diarrhea, and dry mouth with sore throat, but these symptoms can occur at any time
throughout the course of the illness
What is your treatment?
Supportive care and monitoring, possible anti-toxin.
Close evaluation for progression and need for intubation with mechanical ventilation, admission
to the ICU.
In 2010 the CDC announced a new heptavalent (directed at seven types of toxin) botulinum
antitoxin (HBAT) that is now the only antitoxin available in the United States for non-infant
botulism. For suspected cases and to obtain HBAT, clinicians should contact their state health
departments. The state health department (and toxicology) can help you decide if the anti-toxin
should be given. If the clinical suspicion for botulism is high and symptoms are progressing,
antitoxin should be administered as soon as possible and should not be delayed while awaiting
results of diagnostic studies.
Early treatment with antitoxin after exposure to botulinum toxin has been shown to reduce
neurological manifestations. An intravenous human botulism immune globulin (BabyBIG) has
been developed for treatment of infantile botulism and is available through the California
Department of Public Health.
mechanism
classic exam
treatment
Myasthenia Gravis
autoantibodies directed
against the nicotinic
ACh receptor
descending weakness
plasmapheresis or IVIG
with true muscle fatigue,
pupils normal
Botulism
adults: ingested toxin.
infants: ingested spores
(honey)
descending weakness,
anti-toxin for adults, IG
bilateral cranial
for infants
neuropathies, pupils
may be affected, normal
or decreased relfexes
Guillain-Barré syndrome immune mediated
peripheral nerve myelin
sheath or axon
destruction
ascending weakness,
decreased DTRs, back
& extremity pain,
dysautonomia
plasmapheresis or IVIG
Tick paralysis
unknown, ? toxin that
decreased ACh release
ascending weakness,
pupils may be affected
find tick, remove tick
Bell’s Palsy
unknown
unilateral facial
weakness involving
forehead and with
normal eye movements
steroids, protect eye