Neuro /Bells Palsy/TN/Myasthenia Gravis Flashcards
Amygdala
fear and aggression, facial evaluation, social processing, (and odor processing)
Cerebellum
implicit/procedural/motor memory
Implicit memory is skills, action, and emotional conditioning
Prefrontal Cortex
memory encoding and retrieval
Limbic System
Involved in emotional responses:
-controls emotional experience and expression
-can modify the way a person acts
-produces such feelings of fear, anger, pleasure & sorrow
-recognizes life threatening disruptions in a person’s physical or psychological condition and counters them
Initiates fight-or-flight (SNS) system
-Guides a person into behavior that may increase chances for survival
choroid plexus
500 mL CSF formed each day (mainly) by choroid plexus in lateral ventricles.
Cerebellum
General Functions:
Muscle memory
Balance (proprioception)
Equilibrium (vestibular)
Muscle Tone
Coordination
Motor Learning
Bulbar Nerves
CN IX
CN X
CN XI
CN XII
-common “function” of chewing, swallowing, head/neck movement
Lower motor neuron
Alpha motor neurons
To extrafusal muscle fibers
Force generating contractions
lower motor neuron
gamma motor neuron
To intrafusal muscle fibers
Muscle tension and reflex contractions
Bell Phenomenon
Left eye rolls upward and inward
bells palsy
bells palsy
Bell palsy essentials of dx
-Sudden onset of lower motor neuron facial palsy.
Deficits evolve in 72 hours
-Hyperacusis or impaired taste may occur.
-No other neurologic abnormalities.
Bell palsy other potential findings (pain)
Post auricular pain
Concurrent or prodrome
Trigeminal neuralgia ~ 8%
Bells palsy
Sx onset and prognosis
Deficits evolve in 72 hours
Recovery of normal facial function occurs in majority
Bell Palsy: Epi
- Most common etiology of unilateral facial nerve palsy
- Usually adults, peak ages 20-40
- Men and women equally affected
- More often on right side of face
- Rarely occurs in summer
- DM, immunocompromise, preeclampsia
Bells palsy
etiology
HSV hypothesis: after causing primary infection on lips (cold sores), virus travels up sensory nerve axons and resides in geniculate ganglion. At times of stress, virus reactivates and causes local damage to myelin.
Autopsy studies have shown HSV in geniculate ganglion of patients with Bell palsy.
Other potential causes: Lyme disease, syphilis, EBV infection, CMV, HIV; inflammation alone; microvascular disease (DM andHTN). Has also been known to follow recent URI.
May be secondary to autoimmune reactions that cause facial nerve to demyelinate.
bells palsy
Patho
bell palsy
Dx
Unilateral facial palsy of acute onset
Evolved within 72 hours
Ipsilateral postauricular pain/mild to moderate otalgia/hyperacusis or phonophobia
Hypo or dysgeusia
Subjective tongue and facial hypoesthesia
Pfizer vaccine
Facial palsy of known etiology (e.g. Lyme Disease), or a palsy that is progressive, waxing and waning or affects facial zones in an uneven fashion—
is NOT Bells Palsy
Bells palsy
PE
Focused neuro exam, complete head and neck exam including detailed CN exam, otoscopy, and tuning fork exams - Except for ipsilateral facial palsy, the exam should be unremarkable
Bells palsy
Upper vs Lower motor neuron
possible bells palsy?
Uneven distribution?
Vesicles (auditory canal or auricle)?
Suggestive of neoplasm –> imaging
Zoster
bell palsy
red flags
Bells palsy
Dx testing
Imaging when indicated to rule out stroke or neoplasm
Lyme testing if known tick bite or travel to tick endemic area
bell palsy
Tx
bells palsy
eye protection
Artificial tears during the day, tape shut at night with lubricant
bell palsy
Severe cases Tx
For severe cases:
Refer to a Neuro-ophthalmologist and Neurologist for further evaluations and treatments > surgery???
bell palsy
prognosis and follow up
Trigeminal Neuralgia
Essentials of Dx
Brief episodes of stabbing facial pain. [attacks following sensory distribution of CN V, usually right sided]
Pain is in the territory of the second and third division of the trigeminal nerve.
Pain exacerbated by touch.
trigeminal neuralgia
International Headache Society criteria
trigeminal neuralgia
Patients can localize their pain precisely
Trigeminal neuralgia
triggers
Chewing, talking, smiling
Drinking cold or hot fluids
Touching, shaving, brushing teeth, blowing nose
Encountering cold air from open automobile window
Patients carefully avoid rubbing the face or shaving trigger area, in contrast to other facial pain syndromes, in which they massage the face or apply heat or ice
Many patients try to hold face still while talking, to avoid precipitating an attack
trigeminal neuralgia
trigeminal neualgia
more about TN pain
Trigeminal neuralgia
Epi
More likely biologic females than biologic males
Usually begins after age 40, typically 60-70 years
HTN is risk factor
TN
Dx
Characteristic pain distinguishes it from other causes
Labs and imaging not always needed
May use labs as baseline for monitoring treatment drug effects
Imaging if lesion is suspected
TN
Tx
AEDs: Carbamazepine and oxcarbazepine
Inhibit neuronal sodium channel activity, reducing excitability of neurons
Gabapentin, esp in patients with M
Modulation of excitatory transmitters involved in pain
Lamotrigine
Inhibits release of glutamate (excitatory amino acid) and inhibits neuronal sodium channel activity, which stabilizes neuronal membranes, reducing excitability
TN
Surgical Tx (3)
Microvascular decompression
Gamma Knife treatment damages trigeminal nerve to stop transmission of pain signals
Radiofrequency damages trigeminal nerve to stop transmission of pain signals
Tn
complications of surgery
Complications of surgery include permanent anesthesia over face or disabling, spontaneous postop pain (can be worse than original trigeminal neuralgia, and often untreatable)
Many patients require pain medication even after surgery
TN
prognosis
Tends to be chronic
Treatments may fail
Myasthenia Gravis (MG)
Myasthenia Gravis (MG)
general
Autoimmune disorder of postsynaptic membrane at neuromuscular junction
Characteristics
rare
presents at any age
males and females
fatigable muscle weakness:
eyelids (ptosis common) and EOM fatigue
face, neck, extremities & respiratory muscles
Myasthenia Gravis
S/Sx
Partial paralysis of eye movements(ophthalmoparesis), double vision (diplopia), and droopy eyelids (ptosis) are usually among the first symptoms.
> 50% present with ocular symptoms of ptosis and/or diplopia.
Of those who present with ocular sx, half will develop generalized disease within two years.
Weakness and fatigue in neck and jaw also can occur early (Bulbarweakness — impairment of function of CNIX, X, XI, XII) — dysarthria, dysphagia, difficulty holding up the head. About 15% of patients.
Myasthenia gravis
generalized Sx
weakness spreads from face/neck to upper limbs, hands, then lower limbs. (difficult to lift arms overhead, rise from sitting position, walk long distances, climb stairs, grip heavy objects).
Limb weakness alone in 5%
MG
Patho
Immune system attacks Ach receptors on muscle, so muscle can no longer contract in response to Ach release from motor neurons
Mg
Ice Pack test
part of neuro exam if ptosis; based on principle that neuromuscular transmission improves at lower muscle temperatures.
Assess ptosis, fill surgical glove with ice, place on closed lid for two minutes; remove ice and reassess ptosis; improvement is positive test result.
MG
Edrophonium (“Tensilon”) test (historical)
Drug = acetylcholinesterase inhibitor with rapid onset (30 to 45 seconds) and short duration of action (5 to 10 minutes); prolongs presence of acetylcholine in neuromuscular junction and results in immediate increase in muscle strength.
MG
blood Work up
Serum anti-AChR antibodies
positive in 80-90% with generalized MG
Anti-muscle-specific tyrosine kinase (MuSK) antibodies
positive in up to 70% of anti-AChR negative patients
facial, respiratory, proximal muscle weakness
Seronegative for both antibodies ~10%
Consider screening for concurrent thyroid disease
MG
electrical work up
EMG testing: repetitive nerve stimulation shows decremental change in amplitude of muscle response
MG
Imaging
CT or MRI: thymus gland abnormality (thymoma)
MG
Tx
Meds and surgical
- Symptomatic (acetylcholinesterase inhibition) to increase amount of acetylcholine (ACh) available at neuromuscular junction
- Chronic immunosuppressive therapies (glucocorticoids) to target underlying immune dysregulation
- Rapid but short-acting immunomodulating treatments (therapeutic plasma exchange and intravenousimmune globulin[IVIG])
- Surgical treatment (thymectomy)
MG
Mild disease management
- no treatment
- pyridostigmine (cholinesterase inhibitor)
- add corticosteroids if unresponsive to inhibitor
MG
Crisis (severe weakness, respiratory failure)
Tx
- intubation and mechanical ventilation
- plasma exchange/IV immunoglobulin
MG
Moderate disease Tx
pyridostigmine + immunosuppressant (steroids, cyclosporine, tacrolimus)
MG
Thymectomy
patients with thymoma (any age)
May not benefit MuSK antibody+ patients
patients with generalized MG and AChR
antibodies < 60 years of age
