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Short Cases > PNS > Flashcards

PNS Flashcards

1
Q

Myotome Upper limb?

Shoulder Abduction

Elbow flexion

Elbow extension

Finger extension

Finger flexion

Finger abduction

A

Shoulder Abduction: C5

Elbow flexion: C5-C6

Elbow extension: C7

Finger extension: C7

Finger flexion: C8

Finger abduction: T1

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2
Q

Neurological power grading?

A

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

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3
Q

Reflex nerve supply UL?

Biceps

Triceps

Brachioradialis

Finger jerk (Hoffman’s)

A

Biceps: C5

Triceps: C7

Brachioradialis: C6

Finger jerk (Hoffman’s): C8

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4
Q

Dermatome UL?

A
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5
Q

DDx for proximal muscle weakness? (5)

A

Congenital MIND

Congenital: mytochondrial

Metabolic: Cushing’s, Hypothyroidism

Inflammatory: myositis (IBM, DM, PM)

Neuromuscular (MG, LEMS)

Dystrophies (Becker’s, FSHD, Limb girdle)

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6
Q

DDx for bilateral UMN weakness in pyramidal pattern (5)

A

3 M’s

MS

Stroke (Brainstem)

MND

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

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7
Q

Causes of unilateral UMN

A

Work down (brain to cord)

Intracranial - CVA, SOL, MS → hemisensory loss

Brainstem - MS

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

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8
Q

Bilateral LMN (distal weakness) – sensorimotor/sensory polyneuropathy

A

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

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9
Q

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

A

CIDP / GBS

Myopathy (IBM - proximal lower, distal UL)

Myotonic dystrophy

Motor Neurone Disease (progressive muscular atrophy)

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10
Q

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

A

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
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11
Q

DDx for mixed UMN + LMN signs? (3)

A

MND

Cervical myelopathy

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

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12
Q

Causes of cerebellar signs on examination? (8)

A

Stroke, MS, SOL

Alcohol & Drugs (Phenytoin, Lithium, CBZ)

Infection: abscess, TB

Neoplastic: paraneoplastic

SLE

Inherited: Friedrich’s, Spinocerebellar ataxia

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13
Q

Which 3 drugs cause cerebellar dysfunction? (3)

A

CBZ

Phenytoin

Lithium

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14
Q

Pronator drift means? (1)

A

UMN lesion

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15
Q

Lower limb myotome?

A

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

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16
Q

What is UMN pattern weakness in the lower limb?

A

Weak Anti-gravity muscles. That is:

Hip flexion (than hip extension)

Knee extension (than knee flexion)

Ankle dorsiflexion (than plantar-flexion)

17
Q

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

A

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)

18
Q

UMN signs in general (6)

A

Increased tone

Spasticity / Clasp knife

Clonus (not necessarily)

Hyper-reflexia

Upgoing plantars

UMN pattern weakness (anti-gravity muscles)

19
Q

LMN signs in general (6)

A

Muscle atrophy

Fasciculations

Hypotonia / flaccidity

LMN pattern weakness

Areflexia or hyporeflexia

Plantar downgoing

20
Q

Lower limb dermatome?

A
21
Q

Standing on following tests for…

Toes (tippy toes)

Heels

A

Toes - S1

Heels - L4,5

22
Q

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

A

Posterior column lesion

PN (in particular loss of JPS)

Vestibular dysfunction

23
Q

Describe sensory ataxia - signs to look for (4)

A

Ataxic gait

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

Difficulty walking heel to toe

+Ve Romberg’s

24
Q

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

A
  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
25
Q

Name 3 muscle groups supplied by the median nerves.

A
  1. Abductor Pollicis Brevis (thumb abduction)
  2. Flexor digitorum profundus (flexion index finger)
  3. Flexor pollicis longus (thumb flexion)
26
Q

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

A

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

27
Q

3 muscle groups innervated by ulnar nerve

A
  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)
28
Q

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

A
  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)
29
Q

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?

A

Radial nerve lesion at the spiral groove.

Triceps normal as it branches out before the spiral groove.

30
Q

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?

A

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)

31
Q

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?

A

Lesion is in the C7/8 route or brachial plexus.

Involvement of triceps and it’s reflex indicates lesion higher up than radial groove.

32
Q

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

A
  1. Abductor pollicis brevis: median nerve lesion

2 .First dorsal interosseous + Abductor Digiti minimi: ulnar nerve lesion

If all 3 are wasted, several possibilities.

Short Cases (5 decks)

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