Neurolocalisation (CNS + PNS + NMJ disorders) Flashcards
Patient has:
- Tone in legs increased
- Ankle clonus
- Brisk reflexes in knee and ankles
- Upgoing plantars
- Reduced sensation to pin prick and vibration up to belly button
- Normal sensation, tone, power and reflexes in arms
State the location of lesion
Thoracic spinal cord lesion!
UMN signs + paraperesis + affected DCML (reduced vibration and pain) + normal arms (lesion is lower down)
Patient presents with:
- Tone in legs is not increased
- Absent knee and ankle jerks
- Downgoing plantar
State location of lesion.
LMN Lesion
Patient presents with:
- Right facial weakness - facial nerve palsy
- Right pronator drift (weakness), Reflexes on right brisk, Upgoing right plantar
- Right sided arm and leg weakness: grade 4
State location of lesion.
contralateral hemiparesis –> brain
Patient presents with
- UMN symptoms
- double vision
- vertigo
State location of lesion
brainstem !
midbrain or pons probably
Why does brainstem lesions cause
- ipsilateral facial signs
- contralateral limb signs?
Eg: Right sided brainstem lesion
- hits the LMN supplying the right side of face where it exits at the pontomedullary junction
- hits the UMN supplying the left side of body before it decussates at pyramids (medulla)
State the 3 types of pathologies commonly seen in PNS (nerves)
- mononeuropathy
- mononeuritis multiplex
- peripheral neuropathy
In LMN lesion, there are ____ reflexes.
In NMJ and muscle lesions, there are ____ reflexes, until the weakness is super profound.
In LMN lesion, there are ABSENT reflexes.
In NMJ and muscle lesions, there are PARTIAL reflexes, until the weakness is super profound.
State the presentations of lesions in
(1) NMJ
(2) Muscles
(1) NMJ
- proximal weakness in myopathy
- muscle wasting
- fasciculations
- (sometimes) pseudohypertrophy
- no sensory abnormalities
- normal reflexes
(2) Muscles
- proximal and ocular weakness
- fatiguability
- no muscle wasting
- no fasciculations
- no sensory abnormalities
- normal reflexes
State and explain whether proximal or distal muscles get affected first.
PROXIMAL MUSCLES!
- they exert more force than distal muscles
Name the condition. State any wasting and weakness in muscles affected if any.
FASCIOSCAPULOHUMERAL DYSTROPHY
- wasting of trapezius and scapula
- normal power in distal muscles
DUCHENNE MUSCULAR DYSTROPHY
- ____ myopathy
- Cause =
- (1) Symptoms =
- (2) Treatment =
DUCHENNE MUSCULAR DYSTROPHY
- INHERITED myopathy
- Cause = MUTATION IN DYSTROPHIN GENE IN X CHROMOSOME (males higher risk)
- (1) Symptoms =
- early years of development normal
- progressive weakness in proximal muscles first
- affects heart and respiratory muscles
- lordotic posture
- waddling gait
- gower sign (unable to use back extensors)
- death in 30s
- (2) Treatment = corticosteroids + bt gene therapy
Dystrophin stabilises the sarcolemma by anchoring it to ECM and actin –> dystrophin mutation results in sarcolemma unstabilised –> muscle contraction causes high risk of sacrolemma tearing –> muscle breakdown –> scarring and replacement
At synaptic cleft, normally
- Vesicles containing ____ are located in ____ terminal
- ____ influx into ____ terminal causes the vesicles to ____ with ________ membrane
- ____ is reelased into _______ _______ to bind to ____
- ____ breaks down ____ ACh allowing ____ when there is no ____ ____
At synaptic cleft, normally
- Vesicles containing ACETYLCHOLINE are located in PRE-SYNAPTIC terminal
- CA2+ influx into PRE-SYNAPTIC terminal causes the vesicles to FUSE with PRE-SYNAPTIC membrane
- ACETYLCHOLINE is reelased into SYNAPTIC CLEFT to bind to ACETYLCHOLINE-RECEPTOR
- ACETYLCHOLINESTERASE breaks down EXCESS ACh allowing RELAXATION when there is no ACTION POTENTIAL
MYASTHENIA GRAVIS
- Cause = Presence of ____ which is a ____ ____ for ____
- At first, when there is a lot more ____ than ____, there will be no ____
- With sustained ____, ____ competes with ____ for binding to ____
- Exhaustion of ACh from vesicles + ____ of ____ by ____ leads to ____ muscles with sustained contraction
- Test =
State the one extremely important feature of myasthenia gravis.
State some presentations of myasthenia gravis.
MYASTHENIA GRAVIS
- Cause = Presence of ACETYLCHOLINE-RECEPTOR ANTIBODIES which is a COMPETITIVE INHIBITOR for ACETYLCHOLINE RECEPTOR
- At first, when there is a lot more ACETYLCHOLINE than ACETYLCHOLINE RECEPTOR ANTIBODIES, there will be no WEAKNESS
- With sustained CONTRACTION, FEWER ACETYLCHOLINE competes with ACETYLCHOLINE RECEPTOR ANTIBODIES for binding to ACETYLCHOLINE RECEPTOR
- Exhaustion of ACh from vesicles + BREAKDOWN of ACETYLCHOLINE by ACETYLCHOLINESTERASE leads to WEAKER muscles with sustained contraction
- Test = Acetylcholine-receptor antibodies + electrical study to stimulate nerve and measure response
Important feature = FATIGUABILITY
Presentation:
- Bilateral ptosis
- Weakness in proximal muscles of the limbs, i.e. shoulders and thighs
- Intermittent diplopia as weak extra-ocular muscles fail to align the eyes
- Difficulty drinking as epiglottis and soft palate fail to occlude respiratory tract
State some common causes of peripheral neuropathies
- diabetes mellitus
- b12 deficiency
- guillain barre / chronic inflammatory demyelinating polyneuropathy (CIDP)
- iatrogenic
State the common presentation of peripheral neuropathy.
Recall the common causes of peripheral neuropathies.
(1) PRESENTATION
- glove and stocking distribution of weakness and numbness
- affects all 4 limbs (often feet first)
- absent reflexes
(2) CAUSES
1. diabetes mellitus
2. vitamin b12 deficiency
3. guillain-barre syndrome / chronic inflammatory demyelinating polyneuropathy (CIDP)
4. iatrogenic causes
State the common mononeuropathies seen in LL and UL.
UL = median, ulnar, radial nerves
LL = femoral, sciatic nerves
MONONEUROPATHY = MEDIAN NERVE
- common cause =
(1) Sensory
- supply =
- presentation =
(2) Motor
- supply =
- presentation =
MONONEUROPATHY = MEDIAN NERVE
- common cause = compression due to carpal tunnel syndrome
(1) Sensory
- supply = lateral 3.5 digits
- presentation = numbess in lateral 3.5 digits + positive tinel’s test (tapping carpal tunnel results in tingling sensation)
(2) Motor
- supply = flexors + LOAF (lumbricals, opponens pollicis, abductor pollicis brevis, flexor pollicis brevis)
- presentation = thenar wasting + hand of benediction / ape hand (inability to make fist with 1-3rd digits)
MONONEUROPATHY = RADIAL NERVE
(1) Sensory
- supply =
(2) Motor
- supply =
- presentation =
MONONEUROPATHY = RADIAL NERVE
(1) Sensory
- supply = anatomical snuff box area
(2) Motor
- supply = all extensor muscles in arm (finger and wrist extensors), brachioradlialis (only flexor)
- presentation = Wrist drop (saturday night palsy) + paralysed brachioradialis (absent supinator jerk)
MONONEUROPATHY = ULNAR NERVE
- common cause =
(1) Sensory
- supply =
- presentation =
(2) Motor
- supply =
- presentation =
MONONEUROPATHY = ULNAR NERVE
- common cause = compression at medial condyle of humerus
(1) Sensory
- supply = medial 1.5 digits
- presentaiton = reduced sensation to medial 1.5 digits
(2) Motor
- supply = hypothenar eminence, interossei, 3-4th lumbricals, medial half of flexor digitorum profundus
- presentation = hypothenar wasting and guttering, weak finger abduction and adduction + claw hand
MONONEUROPATHY = FEMORAL NERVE
Presentation =
MONONEUROPATHY = FEMORAL NERVE
Presentation =
- strong adduction (if L3 radiculopathy since femoral nerve and obturator nerves supplied by L2-L4 - weak adduction)
- extensive numbness (more than L3 dermatome distribution)
MONONEUROPATHY = SCIATIC NERVE
- common cause =
(1) Sensory
- supply
(2) Motor
- supply =
- presentation =
MONONEUROPATHY = SCIATIC NERVE
- common cause = compression of sciatic nerve due to compression fracture / posterior dislocation of tibia
(1) Sensory
- supply = refer to pic
(2) Motor
- supply = hamstrings, all muscles below knee (common fibular –> deep fibular = dorsiflexors, superficial fibular = fibularis + tibial = plantarflexors)
- presentation = foot drop + weak plantarflexion + weak hip extension and knee flexion
IF damage is due to compression at HEAD OF FIBULA
- foot drop
- strong plantarflexion
- strong hip extension and knee flexion
- strong inversion (tibilalis posterior)
Upper brachial plexus = supplies ____
Lower brachial plexus = supplies ____
Mid brachial plexus = supplies ____
Upper brachial plexus = supplies ROTATOR CUFF AND ELBOW FLEXORS
Lower brachial plexus = supplies INTRINSIC MUSCLES OF HANDS
Mid brachial plexus = supplies EXTENSORS AND WRIST
State some nerve roots where radiculopathies are more common.
C5-7
L4-S1
With reference to ERB’S PALSY, state
- Affected nerve roots
- Cause
- Presentations
With reference to ERB’S PALSY, state
- Affected nerve roots = C5-C6
- Cause = fall that separates neck and shoulder
- Presentations = waiter’s tip (adducted, medially rotated, hyperextended arm)
Less important symptoms
- no more scapular prokection
- no more scapular retraction
- no more abduction
- no more external rotation of arm (axillary n)
- no more elbow flexion (musculocutaneous n)
- no more wrist and finger extension (radial n)
With reference to KLUMPKE’S PALSY, state
- Affected nerve roots =
- Cause =
- Presentations
With reference to KLUMPKE’S PALSY, state
- Affected nerve roots = C8-T1
- Cause = breech birth
- Presentations = claw hand, sympathetic outflow disrupted (similar to brainstem lesion) –> horner syndrome (ptosis + miosis + sweating abnormalities)
With reference to LUMBOSACRAL PLEXUS (__-__) INJURY, state
- Presentation =
- Differentiating factor against sciaticica =
With reference to LUMBOSACRAL PLEXUS (L4-S1) INJURY, state
- Presentation = foot drop, weak plantarflexion, weak hip extension, weak knee flexion
- Differentiating factor against sciaticica = weak hip extension
State everything you know in puffer fish poisoning
PUFFER FISH POISONING
- tetrodotoxin (TTX) in pufferfish affects voltage gated sodium channels found in axons which help propagate action potential
- TTX sensitive sodium channels are in CNS and PNS, TTX resistant sodium channels are in heart
- Toxin does not pass through the BBB and CNS is unaffected – person remains conscious and aware as they experience these symptoms
Presentation
- normal HR
- motor symptoms - absent reflexes, rapidly spreading paralysis and tingling in arms and legs
- shallow rapid breathing
- low oxygen saturation
- vomiting and diarrhoea
Complication = respiratory collapse
Treatment = respiratory support
State the symptoms of horner syndrome
HORNER SYNDROME = sympathetic outflow
- lack of sweating
- miosis
- ptosis
State what is the presentation of Harlequin’s syndrome
HARLEQUIN’S SYNDROME
- one side of face is able to sweat while the other side is unable due to sympathetic defects
State the triad needed for balance.
State the test for proprioceptive problems
- vision
- vestibular
- proprioception
Test = Romberg’s test (patient stands with heels together and closes eyes)
- positive = loss of balance and swaying only when patient closes eyes (sensory ataxia = proprioceptive deficit)
GAZE
- ____ cortex effects sideward gaze through the ____ (____) which is found in the ____
- State the pathway for lateral gaze towards right.
GAZE
- FRONTAL cortex effects sideward gaze through the PARAMEDIAN PONTINE RETICULAR FORMATION (PPRF) which is found in the PONS
Pathway:
1. Activation of left FEF (frontal eye field)
2. Communicates with right PPRF
3. Communicates with left 3rd nerve via MLF (medial longitudinal fasciculus) to supply MR (medial rectus) –> adduction of left eye
4. Communicates with right 6th nerve to supply LR (lateral rectus) –> abduction of right eye
GAZE - LESION IN MEDIAL PONS which interrupts MLF (medial longitudinal fasciculus)
- Recap: MLF is the connection between the PPRF and the contralateral 3rd nerve
- State the resultant presentation
- Name the condition
- State the resultant presentation if MLF is not completely blocked and instead slowed such as in demyelination.
LESION IN MEDIAL PONS = INTERNUCLEAR OPHTHALMOPLEGIA
1. activation of left FEF
2. activation of contralateral right PPRF
3. unable to activate contralateral left 3rd nerve via MLF –> unable to contract left MR (medial rectus) –> unable to adduct left eye
4. activate ipsilateral right 6th nerve –> contract right LR (lateral rectus) –> abduct right eye
MLF partial block –> slow adduction of contralateral eye (contralateral from PPRF, ipsilateral to FEF) = PARTIAL INTERNUCLEAR OPHTHALMOPLEGIA
GUILLAIN-BARRE SYNDROME
- Immune system recognises ____ as ____ ____ Ag due to molecular ____
- Symptoms:
- Complications:
- Treatment:
- Special presentation different from other LMN
GUILLAIN-BARRE SYNDROME
- Immune system recognises GANGLIOCYTES as CAMPYLOBACTER JEJUNI Ag due to molecular MIMICRY
- Symptoms: hypotonia, absent reflexes, numbness, ascending paralysis, mainly affects peripheral nerves
- Complications: Type 2 respiratory failure, cardiac arrhythmias
- Treatment: IVIG, supportive ventilation
- Special presentation different from other LMN = no wasting or fasciculations
Guillain-barre syndrome can also affect nerve roots or brainstem (eye abnormalities, bickerstaff-encephalitis)
