CN Palsies
Which CNs have nuclei in the brainstem? Which part of the brainstem for each?
III,IV = Midbrain
V,VI,VII,VIII = Pons
IX, X, XI(?), XII = Medulla
bulbar muscles are heavily involved in what action? What is the risk when our bulbar CNs get injured?
Swallowing, risk of aspiration or asphyxiation.
Name which spinal cord tracts are sensory or motor
Corticospinal
Spinothalamic
Corticobulbar
Dorsal Column Medial Lemniscus
Bonus: what kinds of sensation? motor to what muscle groups?
Corticospinal - motor (most skeletal movement)
Spinothalamic - sensory. pressure & crude touch (anterior), pain & temperature (lateral)
Corticobulbar - motor (CNs, facial expression & bulbar muscles)
Dorsal Column Medial Lemniscus - sensory (vibration, fine touch, proprioception
UMN pathology results in _______, while LMN pathology results in _______.
Spasticity/rigidity, Flaccid paralysis.
Remember that in complete SCI, starts with flaccid paralysis, hyporeflexia then devolves into spasticity, hyperreflexia. (dont ask me why)
what is the "classic distribution" in polyneuropathies?
Stocking-glove distribution (longest axons affected first). Sensory symptoms prior to motor symptoms, usually.
II
III
IV
VI
VI - Abducens
Which of the following physical exam tests examine function of CNIII?
Pupillary Light Reflex
Eyelid elevation
Accommodation
H Test
A palsy of CNIII results in what?
All!
Globe deviates down and out
only working muscles are lateral rectus (CNVI) & superior oblique (CNIV)
Bilateral quadriparesis and Bilateral sensory loss in a "cape-like distribution" would involve which of the following?
Anterior Cord Syndrome
Posterior Cord Syndrome
Central Cord Syndrome
Brown Sequard Syndrome
Central cord syndrome.
Tx with immobilization, PT/OT. Surgery uncommon.
Explain how neurogenic shock can happen with SC injuries
With some spinal cord injuries, it can disrupt the autonomic nervous system, preventing information from arterial baroreceptors from being received -> loss of compensatory sympathetic tone -> bradycardia/hypotension
Commonly associated with SCI above T6, greater risk the higher you go.
You have a 7 year old patient who is brought in by his concerned mom for being "clumsy" and not being able to play sports with his friends. on exam, you notice paresis with resisted dorsiflexion, and a noticeably high arch in the foot that doesn't flatten with weightbearing. What dx are you concerned about, and what should you ask the mom?
Concern for Charcot-Marie-Tooth disease, ask mom if there is any family history. (hereditary, most common demyelinating polyneuropathy).
Tx is mostly supportive eg. (normal life expectancy, loss of ambulation is rare)
Left
In trigeminal nerve palsies involving jaw deviation due to mandibular branch involvement (Muscles of mastication), the jaw deviates toward the side of the lesion.
A CN palsy of the right CN XII would result in tongue deviation _____ the site of injury.
tongue deviation towards the side of palsy
also ipsilateral facial paralysis, dysphagia, dysarthria
The lateral horn of the spinal cord is not found at every level of the spine. However, it is found on 17 segments. Which segments is it found in?
T1-L2 = Sympathetic chain
S2-S4 = Parasympathetic chain
*the lateral horn holds autonomic cell bodies*
In regards to CN VII, how can we differentiate an upper motor neuron lesion vs a lower motor neuron lesion?
upper facial muscles (eg. forehead, eyebrow) have bilateral UMN innervation with one LMN
Lower facial muscles have one UMN, one LMN.
UMN lesion = upper facial muscles spared, lower facial muscles affected
LMN lesion = all facial muscles on one side affected.
unlike other polyneuropathies, _______ distribution is NOT based on axonal length, and can initially affect proximal and distal muscles.
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
Whats the MRI sign name? (think Shrek)
The vagus nerve is involved in the rise of the palate and uvula during swallowing and speaking. In a left CN X palsy, which way would the uvula deviate?
A patient presents to you with a 2 week onset of intermittent shocks of pain in the face, particularly on the left side. He seems to note that this recurs throughout the day with eating/drinking or brushing teeth. He has no neurological deficits or complaints. What CN is likely involved and how do we diagnose/treat?
Trigeminal neuralgia.
Dx is a clinical diagnosis but a cause can often be found on MRI (eg. tumors, MS), get MRI if concerning symptoms (other neuro deficits eg hearing loss)
treat with carbamazapine (sodium channel blocker anticonvulsant)
Name what types of neural tissue (eg. motor/sensory/autonomic) is present at each site of the spinal cord
Dorsal Horn
Dorsal Column
Lateral Horn
Lateral Column
Ventral Horn Ventral Column
Dorsal Rami
Ventral Rami
White Rami
Grey Rami
Horn = Gray matter = cell bodies, unmyelinated axons
Column = White Matter = myelinated axons
Dorsal Horn - Sensory
Dorsal Column - sensory
Lateral Horn - autonomic cell bodies
Lateral Column - mixed sensory/motor
Ventral Horn - motor
Ventral Column - sensory/motor
Dorsal Rami - sensory (skin on back)/motor (deep back musc.)
Ventral Rami - sensory/motor (everything else)
White Rami - preganglionic symp. neuron axon, myelinated
Grey Rami - postganglionic symp. neuron axon, unmyelinated.
Name where each of the following spinal cord tracts decussate
Spinothalamic tract (both ant/lateral div)
DCML
Anterior Corticospinal tract
Lateral Corticospinal tract
Spinothalamic = spinal cord
DCML = medulla
Anterior Corticospinal = spinal cord
Lateral corticospinal = medulla
Way to remember:
SPINOthalamic decuss. at SPINAL cord, DCML = DeCussates at MeduLLa.
Lateral corticospinal tract starts with an L, so it goes along with DCML (decuss. at medulla). Anterior needs a buddy so they go along with spinothalamic (decuss at SC)
A 28 year-old female presents to the clinic complaining of a "prickly sensation" that started bilaterally in her feet two days ago and difficulty walking. She now has the dysesthesia from her mid-thigh down to her toes. On physical examination she has diminished pain and temperature sensation, absent reflexes, loss of proprioception in her legs bilaterally, and muscle strength is 1+/5+ in the lower extremities and 5+/5+ in the upper extremities. What is the most likely diagnosis?
A Guillain-Barré syndrome
B Multiple sclerosis
C Myasthenia gravis
D Spinal cord compression
Guillain-Barré syndrome
Name the afferent and efferent limbs for each of the following reflexes
Pupillary light reflex
Accomodation
Corneal reflex (blink)
Gag reflex
Vestibuloocular reflex
Pupillary light reflex - II(a), III(e)
Accomodation - II(a), III(e)
Corneal reflex (blink) - V1(a), VII(e)
Gag reflex - IX(a), X(e)
Vestibuloocular reflex - VIII(a), III, IV, VI (e)
Compare and contrast Ramsay-Hunt Syndrome and Bell Palsy. How do each present? How do we treat?
Ramsay Hunt:
-Caused by VZV. (shingles of geniculate ganglion)
-Classic triad: Ear Pain, Vesicles in auditory canal/external ear, ipsilateral facial paralysis
-treat with antivirals, eyepatch (decrease corneal abrasion risk)
Bell Palsy:
-Acute idiopathic CN VII palsy, usually entire face on one side. (does not spare forehead)
-Treat with short course of steroids? Eye patch too.
-tend to resolve within 1mo
Brown sequard syndrome is due to a lateral hemisection of the spinal cord, meaning all tracts on one side affected. If the left side is affected, which side will have sensory deficits, and which side will have motor deficits/paresis? Why?
Left side: paresis/paralysis (Lateral corticospinal tract decussates at medulla so ipsilateral side affected) as well as loss of sensation to fine touch, proprioception, vibration (DCML decussates at medulla)
Right side: Sensory loss to pain and temperature (spinothalamic tract decussates at SC),
Anterior cord syndrome would produce what types of motor and sensory deficits?
Motor: BIL paralysis below site of lesion (both anterior and lateral corticospinal tracts end up in ventral horn)
Sensory: Loss of pain, temperature sensation below site of lesion (anterior spinothalamic tract)
DCML, corticobulbar tracts spared. May have autonomic dysfn if lateral horn involved.
A 72 year-old man with a long-standing history of
diabetes mellitus, renal insufficiency, and hypertension presents to the clinic complaining of burning and tingling pain in his feet. What's your next step?
A) EMG/NCS
B) Recommend OTC NSAIDs/Tylenol/ASA
C) Rx Amitriptyline
D) Lab panel to determine cause
C) Rx Amitriptyline
SNRIs, TCAs, Gabapentinoids for peripheral neuropathies. Apparently Amitriptyline particularly for diabetic neuropathy.
EMG/NCS unnecessary d/t obvious explanation
NSAIDs will kill his kidneys
Obvious cause = no labs necessary, but maybe to get A1c to manage DM.