Neurology Focal Weakness

Question 1

what is the difference in symptoms of a stroke compared to lower motor neurone (LMN) facial weakness aka bells palsy

Answer 1

typically strokes cause an UMN facial weakness, and nearly always with UMN weakness of the ipsilateral arm and leg. Stroke comes on suddenly whereas bells palsy often takes a series of hours to gradually notice

UMN the forehead will be spared and the patient can move their forehead on the affected side

LMN the forehead will not be spared and the patient cannot move their forehead on the affected side

Question 2

why is neuroimaging not indicated for bells palsy

Answer 2

it is an isolated lower motor neurone facial weakness and likely to be idiopathic

Question 3

what information can you tell a patient about bells palsy

Answer 3

recurrence is uncommon
facial weakness can worsen over the first few days but the majority recover completely within 4-6 months
tape can be used to keep the eye closed at night

Question 4

where does the facial nerve exit the brainstem and on its journey to the face what structures does it pass

Answer 4

cerebellopontine angle

passes the temporal bone and parotid gland

Question 5

name the 5 divisions of the facial nerve

Answer 5

To Zanzibar By Motor Car 
temporal 
Zygomatic 
Buccal 
Marginal mandibular 
Cervical

Question 6

what are the motor function of the facial nerve

Answer 6

Supplies the muscles of facial expression, the stapedius in the inner ear and the posterior digastric, stylohyoid and platysma muscles in the neck.

Question 7

what are the sensory functions of the facial nerve

Answer 7

Sensory: carries taste from the anterior 2/3 of the tongue

Question 8

what are the parasympathetic functions of the facial nerve

Answer 8

parasympathetic supply to the submandibular and sublingual salivary glands and the lacrimal gland (stimulating tear production).

Question 9

tell me about the nerve innervation of the forehead

Answer 9

Each side of the forehead has upper motor neurone innervation by both sides of the brain.
Each side of the forehead only has lower motor neurone innervation from one side of the brain.

Question 10

if patients present with bells palsy within 72 hours of developing symptoms nice recommending considering which medications

Answer 10

prednisolone either 50mg for 10 days or 60mg for 5 days followed by a 5 day reducing regime of 10mg a day

CKS don’t recommend antiviral but someone clinicians use acyclovir

Question 11

as well as prednisolone what else should be prescribed for someone with bells palsy

Answer 11

lubricating eye drops to prevent the eye on the affected drying out

need an ophthalmology review for exposure keratopathy if develop pain in the eye

Question 12

a common differential to bells palsy is Ramsay-hunt syndrome, how does this present and what is it caused by

Answer 12

caused by varicella zoster virus (VZV) aka herpes zoster (shingles) and presents as a unilateral lower motor neurone facial nerve palsy
patients typically have painful and tender vesicular rash in the ear canal, pinna and around the ear on the affected side. Rash can extend to the anterior 2/3 of the tongue and hard palate (treatment same as bells palsy)

Question 13

name some infections that can cause LMN facial nerve palsy

Answer 13

Otitis media
Malignant otitis externa
HIV
Lyme’s disease

Question 14

name some systemic diseases that can cause LMN facial nerve palsy

Answer 14

Diabetes
Sarcoidosis
Leukaemia
Multiple sclerosis
Guillain–Barré syndrome

Question 15

name some traumas that can cause LMN facial nerve palsy

Answer 15

Direct nerve trauma
Damage during surgery
Base of skull fractures

Question 16

when patient presents with facial weakness what questions do you need to ask

Answer 16

time of onset, any headaches or other symptoms, any changes in eye movements or vision, and changes to sensation of the face, FAST

Question 17

when a patient presents with a 3 day history of weakness to the foot what questions need to be asked

Answer 17

Ask specially about back pain, especially any radiation to the leg, any numbness or tingling, any bladder problems

Is there any history of trauma, this could be a consequence of problems to do with the lumbar spine

Useful to know if she has been involved in any unusual activity prior to onset of these symptoms

Could this be due to a squishing of a nerve

Question 18

what are the main differentials of foot weakness

Answer 18

lumbar nerve root lesion (radiculopathy) or common peroneal nerve palsy

Question 19

what is the main difference between a lumbar nerve root lesion (radiculopathy) and common peroneal nerve palsy

Answer 19

A prolapsed intervertebral disc (L4/5) would almost always be associated with significant back pain & loss of the ankle reflex on the same side

A common peroneal nerve palsy is typically painless, the ankle reflex is preserved and often occurs after a period of unaccustomed activity involving prolonged kneeling

Question 20

which muscles does the common perineal (fibular) nerve innervate and what are the muscles responsible for

Answer 20

tibialis anterior, responsible for ankle dorsiflexion, and the peroneal muscles which evert the foot (therefore can move foot up)

not tibialis posterior (tibial nerve) which is responsible for inversion

Question 21

how is the foot movement different between a L5 root compression and just a common perineal nerve injury

Answer 21

a slipped disc would cause weakness in both the inversion and eversion of the foot as the L5 root contributes significantly to the tibialis anterior, peroneal muscle and tibialis posterior

Question 22

why is the ankle reflex lost in L5 root compression

Answer 22

A slipped disk causing significant L5 root compression enough to cause a footdrop will almost always involve the S1 root in addition, and hence involves loss of the ankle reflex

Question 23

name the 2 terminal branches of the sciatic nerve and what does the sciatic nerve innervate

Answer 23

tibial nerve (posterior leg and intrinsic muscles of the foot) 
common fibular nerve (anterior leg, lateral leg and remaining intrinsic foot muscles) 

posterior thigh, entire leg and entire foot

Question 24

what things should you ask about when taking a foot drop history

Answer 24

ask about external pressure to the knee
precipitating factors for peroneal mononeuropathy
medical history
observe a patients gait
look for swelling and erythema
look for fasciculations in the legs and arms
assess strength of the muscles

Question 25

in a foot drop history, what things can cause external pressure on the knee

Answer 25

habitual leg crossing, prolonged squatting or kneeling (could be work related), confinement to bed, use of leg brace or recent plaster cast below the knee

Question 26

in a foot drop history, what precipitating factors an lead to peroneal mononeuropathy

Answer 26

recent weight loss, overstitching from an injury, mass in the popliteal space (eg bakers cyst)

Question 27

in a foot drop history, what things from a medical history could be of relevance

Answer 27

diabetes, alcohol misuse, vitamin B deficiency or chemotherapy

Question 28

in a patient with common fibular nerve injury what could their gait look like and why

Answer 28

high stepping gait (to prevent foot from dropping) is a sign of severe weakness of the dorsiflexion muscles

Question 29

in a foot drop history, what does swelling and erythema suggest

Answer 29

trauma or compartment syndrome

Question 30

in a foot drop history, what do fasciculations in the arms and legs suggest

Answer 30

motor neurone disease

Question 31

which nerve is responsible for foot dorsiflexion and eversion

Answer 31

peroneal nerve

Question 32

which nerve is responsible for foot plantar flexion and inversion

Answer 32

tibial nerve

Question 33

which nerve is responsible for him abduction

Answer 33

superior gluteal nerve, L5 root

Question 34

in wrist drop which nerve is affected

Answer 34

radial nerve

Question 35

which muscles does the radiation nerve innervate

Answer 35

triceps and posterior compartment of the forearm (brachioradialis and extensor carpi radials longs) which act to extend the arm at the elbow

Question 36

which nerve is injury in claw hand injury and why

Answer 36

ulnar nerve as this supplies the hypothenar eminence and intrinsic muscles of the hand therefore cannot extend fingers at the IP joint

affects the little and ring finger

Question 37

which nerve is injured in the hand of benediction/bishops hand and why

Answer 37

median nerve

wasting of anterior forearm and thenar eminence therefore can’t flex the middle and index finger

Question 38

which nerve is primarily affected in carpal tunnel syndrome

Answer 38

the median nerve

Question 39

where does compression of the ulnar nerve commonly occur and what does this cause

Answer 39

at the elbow and can cause inability to extend little and ring finger