Neuro - Cranial nerves and neuroanatomy qs Flashcards
Signs and Causes of CN III (third) palsy
Signs of CN III palsy:
- Ptosis (partial ptosis = incomplete palsy)
- Eye down and out (divergent strabismus)
- Absent direct light/consensual/accomodation reflexes
- Exclude CN IV lesion by tilting head to affected side – eye intorts if CN IV intact
Causes:
- Central - Vascular, tumour, demyelination, trauma, idiopathic
- Peripheral - compressive lesion (Posterior communicating artery/PCA aneurysm, raised ICP, nasopharangeal ca, orbital lesions, basal meningitis), infarction, trauma, caverous sinus lesions
Pupil Sparing Causes 4MT:
- (Diabetes) Mellitus
- Myopathy
- Myasthenia
- Muscular Dystrophy
Thyroxotic opthalmopathy
Signs and Causes of CN IV Palsy
Signs of CN IV Palsy
- Unable to look down with eye adducted
- Diplopia resolves with head tilted to opposite shoulder
Causes:
- isolated IV palsy is rare usually idopathic or related to trauma, occasionally may occur with lesions of the cerebral peduncle
What are the causes of fifth (V) cranial nerve palsy? Any way they can be grouped?
Hints
- all 3 divisions = ganglion or more proximal
- one division involved = postganglionic
- lost pain but preserved light touch = brain stem or upper cervical cord
- lost light touch but preserved pain = pontine nucleus
Central (pons, medulla, upper cervical)
- vascular
- tumour
- syringobulbia
- MS
Posterior fossa
- aneurysm
- tumour (skull base, like in acoustic neuroma)
- chronic meningitis
Trigeminal ganglion (petrous temporal bone)
- meningioma
- fracture of the middle fossa
Cavernous sinus (associated 3rd, 4th, 6th palsies)
- aneurysm
- thrombosis
- tumour
Other
- sjogren’s
- SLE
- toxins
- idiopathic
What are the clinical features and causes (bilateral and unilateral) of sixth (VI) cranial nerve palsy?
Features
- failure of lateral eye movement
- affected eye deviated inwards in severe lesions
- diplopia: maximal to the affected side, with images horizontal and parallel. Outermost image from affected eye, disappearing on covering
Bilateral
- trauma
- wernicke’s
- raised ICP
- mononeuritis multiplex
Unilateral
- central
- a. vascular
- b. tumour
- c. wernicke’s
- d. MS (rare)
- peripheral
- a. diabetes, other vascular lesions
- b. trauma
- c. idiopathic
- d. raised ICP
What are the causes of seventh VII (facial) cranial nerve palsy?
UPPER MN (between cortex and brainstem) (spares the forehead)
- vascular
- tumour
LOWER MN (brainstem and distal)
Pontine (look for 5 and 6 palsy)
- vascular
- tumour
- syringobulbia
- MS
Posterior fossa
- acoustic neuroma
- meningioma
Petrous temporal
- Bell’s palsy
- Ramsay-Hunt syndrome
- otitis media
- fracture
Parotid
- tumour
- sarcoid
Bilateral
- GBS
- bilateral parotid disease (sarcoid, sjogren, etc)
- mononeuritis multiplex
- don’t forget myopathy and NMJ defects in bilateral facial weakness
What are the causes of twelfth XII (hypoglossal) cranial nerve palsy?
UPPER MN
- vascular
- MND (motor neurone disease)
- tumour
- MS
LOWER MN- unilateral
Central
- vascular (vertebral)
- MND
- syringobulbia
Peripheral (posterior fossa)
- aneurysm
- tumour
- chronic meningitis
- trauma
- arnold-chiari malformation
- base of skull fracture/tumour
Lower - bilateral
- MND
- arnold-chiari malformation
- GBS
- polio
What are the clinical features and causes of third (III) cranial nerve palsy?
- *Features**
- complete ptosis (partial in incomplete lesion)
- divergent strabismus (eye is down and out)
- dilated pupil, unresponsive to direct or consensual light or accomodation
- *Always exclude a fourth nerve lesion**
- tilt head to the same side as the lesion
- affected eye will intort if fourth nerve is intact
- can also ask them to look down and to opposite side of lesion and look for intortion
Central - (DVTT)
- Demyelination
- Vascular - CVA
- Tumour
- Trauma
- Idiopathic
Peripheral
- compressive
- a. aneurysm (usually PComA)
- b. tumour -> raised ICP (pupil dilates early)
- c. nasopharyngeal carcinoma
- d. orbital lesions (Tolosa-hunt syndrome from compression of superior orbital fissure: 3rd, 4th, 6th, V1+2)
- e. basal meningitis
- infarction: diabetes, arteritis (usually spares the pupil)
- trauma
- cavernous sinus
What should you think of in multiple cranial nerve palsies?
Cancer, cancer, cancer
Causes
- nasopharyngeal carcinoma
- chronic meningitis (carcinoma, tuberculosis, sarcoidosis)
- GBS (spares 1, 2, 8). Don’t forget miller fisher variant
- brain stem lesions (crossed sensory/motor signs). Vascular, gliomas, MS
- arnold-chiari malformation
- trauma
- base of skull lesion (paget’s, meningioma, metastasis)
- mononeuritis multiplex (rare: diabetes, vasculitis, etc)
What are the findings in common peroneal nerve lesion
(L4, L5, S1)
- Foot drop and loss of foot eversion only. High stepping gait
- Sensory loss (minimal) over the dorsum of the foot
- Normal reflexes
**Preserved INVERSION
Ddx
- common peroneal - compression, trauma, fracture, surgery
- L4/L5 - disc prolapse, degenerative, trauma surgery, tumout
What are the findings in complete brachial plexus lesion?
What about Upper trunk?
What about Lower trunk?
Make sure to look for axillary lymphadenopathy at the end
- and radiation/surgical/sternotomy, etc scars
Complete
- LMN signs of whole arm
- sensory loss of whole limb
- Horner’s (great clue; only if proximal in lower plexus)
Upper (Erb-Duchenne; C5/6) (waiter’s tip position)
- weakness: shoulder movement, elbow flexion
- sensory loss of lateral arm, forearm, thumb
Lower (Klumpke; C8/T1)
- weakness: claw hand with all intrinsic muscles paralysed
- sensory loss of ulnar side of hand and forearm
- Horner’s
What are the findings in femoral nerve lesion
(L2, L3, L4)
- weakness of knee extension (quadriceps paralysis)
- Slight hip flexion weakness
- Preserved adductor strength
- Loss of knee jerk
- Sensory loss involving the inner aspect of the thigh and leg
What are the findings in radial nerve lesion?
(C5-C8)
- Wrist and finger drop (wrist flexion normal)
- Triceps loss (elbow extension loss) if lesion is above the spiral groove
- Sensory loss over the anatomical snuff box
- Finger abduction appears to be weak because of the difficulty spreading the fingers when they cannot be straightened
What are the findings in sciatic nerve lesion
(L4, L5, S1, S2)
- Weakness of knee flexion (hamstrings involved)
- Loss of power of all the muscles below the knee causing a foot drop, so they may be able to walk, but cannot stand on the toes or heels
- Knee jerk intact
- Loss of ankle jerk and plantar response
- Sensory loss along the posterior thigh and total loss below the knee
What are the motor and reflex findings in midthoracic spinal cord compression?
What about at T10-11?
Midthoracic
- intercostal paralysis (clinically undetectable)
- loss of upper abdominal reflexes at T7/8
- UMN signs in LLs
- sensory level on the trunk (don’t miss)
T10/11
- loss of lower abdominal reflexes
- upward displacement of umbilicus on contraction of abdominal muscles (Beevor’s sign)
- UMN signs in LLs
What are the motor and reflex findings in spinal cord compression at:
L1?
L4?
L5/S1?
S3/4?
L1 (conus medullaris)
- cremasteric reflex lost with normal abdominal reflexes
- UMN signs of lower limbs
L4
- LMN weakness/wasting of quadriceps
- absent knee jerk
L5/S1
- LMN weakness of knee flexion, hip extension/abduction, calf and foot muscles
- present knee jerk
- absent ankle jerk and plantar response
- present anal reflex
S3/4
- normal lower limbs
- absent anal reflex
- saddle sensory loss
Upper limb dermatomes
