PNS

Question 1

Myotome Upper limb?

Shoulder Abduction

Elbow flexion

Elbow extension

Finger extension

Finger flexion

Finger abduction

Answer 1

Shoulder Abduction: C5

Elbow flexion: C5-C6

Elbow extension: C7

Finger extension: C7

Finger flexion: C8

Finger abduction: T1

Question 2

Neurological power grading?

Answer 2

5: Normal

4+: Sub-maximal against resistance

4: Moderate movement against resistance

4-: Slight movement against resistance

3: Against Gravity (but not against resistance)

2: Move with gravity eliminated
1: Flicker only

Question 3

Reflex nerve supply UL?

Biceps

Triceps

Brachioradialis

Finger jerk (Hoffman’s)

Answer 3

Biceps: C5

Triceps: C7

Brachioradialis: C6

Finger jerk (Hoffman’s): C8

Question 4

Dermatome UL?

Answer 4

Question 5

DDx for proximal muscle weakness? (5)

Answer 5

Congenital MIND

Congenital: mytochondrial

Metabolic: Cushing’s, Hypothyroidism

Inflammatory: myositis (IBM, DM, PM)

Neuromuscular (MG, LEMS)

Dystrophies (Becker’s, FSHD, Limb girdle)

Question 6

DDx for bilateral UMN weakness in pyramidal pattern (5)

Answer 6

3 M’s

MS

Stroke (Brainstem)

MND

Myelopathy (cervical myelopathy, SOL, disc-prolapse, TVM, Syrinx)

Question 7

Causes of unilateral UMN

Answer 7

Work down (brain to cord)

Intracranial - CVA, SOL, MS → hemisensory loss

Brainstem - MS

Spinal cord ↘ sensory level 🡪 trauma, SOL, abscess, AVM/haemorrhage

Question 8

Bilateral LMN (distal weakness) – sensorimotor/sensory polyneuropathy

Answer 8

DAM IT VICH

Drugs & Toxins: Amiodarone, chemotherapy (cisplatin, vincristine), colchicine

Alcohol, Amyloid

Metabolic: Diabetes, uraemia, hypothyroid

Immune: GBS, CIDP

Tumour: paraneoplastic

Vitamin B12, B1, B5, B6 deficiency, Vasculitis

Infection: Lyme disease, HIV

Connective tissue diseases: SLE, PAN, Sjogrens

Hereditary: CMT, Friedrich’s ataxia

Question 9

Bilateral LMN: distal motor weakness without sensory alterations – distal motor neuropathy (4)

Answer 9

CIDP / GBS

Myopathy (IBM - proximal lower, distal UL)

Myotonic dystrophy

Motor Neurone Disease (progressive muscular atrophy)

Question 10

Causes of unilateral LMN pattern weakness? (3 broad, 4 specifics each)

Answer 10

Nerve root to the peripheral nerve (All of below can be caused by - Compression, Trauma, Tumour, Infection). PN has few more (endocrine, mononeuritis)

1. Radiculopathy: dermatomal sensory loss
2. Plexopathy: vast dermatomal sensory loss
3. Peripheral nerve palsy
   
   • Endocrine: diabetes, hypothyroidism, acromegaly, obesity
   • Mononeuritis Multiplex

Question 11

DDx for mixed UMN + LMN signs? (3)

Answer 11

MND

Cervical myelopathy

Dual pathology (e.g. cervical myelopathy + PN)

Question 12

Causes of cerebellar signs on examination? (8)

Answer 12

Stroke, MS, SOL

Alcohol & Drugs (Phenytoin, Lithium, CBZ)

Infection: abscess, TB

Neoplastic: paraneoplastic

SLE

Inherited: Friedrich’s, Spinocerebellar ataxia

Question 13

Which 3 drugs cause cerebellar dysfunction? (3)

Answer 13

CBZ

Phenytoin

Lithium

Question 14

Pronator drift means? (1)

Answer 14

UMN lesion

Question 15

Lower limb myotome?

Answer 15

As below.

Other than that:

Hip adduction: L2,3

Hip abduction: L4,5

Ankle inversion: L4,5

Ankle eversion: L5-S1

Big toe extension: L5 only

Question 16

What is UMN pattern weakness in the lower limb?

Answer 16

Weak Anti-gravity muscles. That is:

Hip flexion (than hip extension)

Knee extension (than knee flexion)

Ankle dorsiflexion (than plantar-flexion)

Question 17

What is LMN pattern weakness in LL? (muscle groups)

Answer 17

Exact opposite of UMN pattern weakness:

Hip extension (weaker than hip flexion)

Knee flexion (weaker than knee extension)

Ankle plantar flexion (weaker than dorsi-flexion)

Question 18

UMN signs in general (6)

Answer 18

Increased tone

Spasticity / Clasp knife

Clonus (not necessarily)

Hyper-reflexia

Upgoing plantars

UMN pattern weakness (anti-gravity muscles)

Question 19

LMN signs in general (6)

Answer 19

Muscle atrophy

Fasciculations

Hypotonia / flaccidity

LMN pattern weakness

Areflexia or hyporeflexia

Plantar downgoing

Question 20

Lower limb dermatome?

Answer 20

Question 21

Standing on following tests for…

Toes (tippy toes)

Heels

Answer 21

Toes - S1

Heels - L4,5

Question 22

Romberg’s +ve (steady with eyes open but unsteady with eyes closed) causes? (3)

Answer 22

Posterior column lesion

PN (in particular loss of JPS)

Vestibular dysfunction

Question 23

Describe sensory ataxia - signs to look for (4)

Answer 23

Ataxic gait

Wide-based, foot slapping on the ground (“stamping gait”)

Difficulty walking heel to toe

+Ve Romberg’s

Question 24

3 differential diagnosis of LMN pattern foot drop & how would you distinguish between them?

Answer 24

1. Common peroneal nerve injury
2. Sciatic nerve injury
3. L5 radiculopathy

Q1. Are all reflexes intact?

• If no (i.e. either ankle jerk and plantar reflex is absent/reduced) - sciatic neuropathy
• If yes: L5 or common peroneal injury (these do not affect reflexes).

Q2. Is foot inversion (superficial peroneal) and ankle plantar flexion (deep peroneal) normal?

• If yes: common peroneal neuropathy. CMN runs laterally, and mediates ankle eversion. Thus common peroneal nerve mononeuropathy does not involve ankle inversion.
• If no: L5 radiculopathy. It involves both tibial (ankle inversion) and peroneal (ankle eversion). Both ankle plantar-flexion dorsal-flexion affected. Toe extension is typically weak.

Q3. Sensory loss

• Limited to lateral leg and dorsal foot (L5) only: L5 radiculopathy
• Involves entire lower leg (except medial calf - saphenous nerve, a femoral nerve branch), but spares above knee -> sciatic neuropathy

Question 25

Name 3 muscle groups supplied by the median nerves.

Answer 25

1. Abductor Pollicis Brevis (thumb abduction) 2. Flexor digitorum profundus (flexion index finger) 3. Flexor pollicis longus (thumb flexion)

Question 26

How do you differentiate between proximal (e.g. carpal tunnel) vs. distal median nerve palsy?

Answer 26

**1. Sensation of the thenar eminence** If the sensation of the thenar eminence is spared (blue areas), this mean that the _palmar cutaneous branch is spared_, hence the lesion is more likely to be _distal_ lesion (i.e. after palmar cutaneous branch has branched out). **2. In CTS (distal lesion), only APB is affected** (abductor pollicis brevis) In proximal lesion, additionally, there is: a) benediction sign (when asked to make a fist), b) weak index finger flexion, flexor pollicis Longus, c) wrist flexion weakness

Question 27

3 muscle groups innervated by ulnar nerve

Answer 27

1. First dorsal interosseous (this is what you test for but it innervates all interossei) 2. Abductor digiti minimi 3. Flexor digitorum profundus (little finger)

Question 28

How do you differentiate between proximal vs. distal ulnar nerve palsy? (3)

Answer 28

1. **Clawing is worse with distal lesion** - Common cause = compression at wrist - Guyon canal - Spares ulnar FDP which flexes IPJs → FDP extension, which opposes IPJ flexion caused by weakened lumbricals (ulnar paradox) 2. **Sparing of hypothenar eminence** 3. Weak ulnar flexion at the wrist in proximal lesion (e.g. cubital canal compression at elbow)

Question 29

Wrist drop can results from the following. Other than weakness of finger and wrist extension, Weak arm flexion - brachioradialis Normal arm extension - triceps Where is the lesion?

Answer 29

Radial nerve lesion at the spiral groove. Triceps normal as it branches out before the spiral groove.

Question 30

Wrist drop can results from the following. Weak finger extension Radial deviation of wrist on attempted extension Triceps intact No sensory loss, normal reflex. Where is the lesion?

Answer 30

Radial deviation indicates weakened extensor carpi ulnaris Radial deviation also indicates intact extensor carpi radialis longus (ECRL), so the lesion must be after ECRL branches out. Hence the lesion is in PIN (posterior interosseous nerve) This is rare but could be due to mononeuritis multiplex (or simplex) of any causes, such as diabetes or connective tissue disease)

Question 31

Wrist drop can result from the following. Finger extension weakness Radial deviation of the wrist on the attempted extension Weak arm flexion - brachioradialis Weak arm extension - triceps Reduced/Absent triceps reflex Where is the lesion?

Answer 31

Lesion is in the C7/8 route or brachial plexus. Involvement of **triceps** and **it's reflex** indicates lesion higher up than radial groove.

Question 32

3 areas to look at for muscle wasting in hand? - which muscles? - wasting of these muscles indicate which nerve injury?

Answer 32

1. Abductor pollicis brevis: median nerve lesion 2 .First dorsal interosseous + Abductor Digiti minimi: ulnar nerve lesion If all 3 are wasted, several possibilities.