Weakness

Question 1

If weakness involves one limb plus sensory changes, where is the lesion likely?

Answer 1

Root or plexus, since both motor and sensory fibers are affected.

Question 2

What are common causes of root or plexus lesions?

Answer 2

• Older person with previous trauma → disc disease
• Diabetes → ischemia of roots/plexus

Question 3

What symptom is characteristic of cervical radiculopathy?

Answer 3

Pain radiating down one arm along a specific dermatomal distribution.

Question 4

How does the location of a disc affect symptoms?

Answer 4

• Laterally extending disc → root symptoms
• Caudally extending disc → cord symptoms

Question 5

What questions help localize the lesion in cervical radiculopathy?

Answer 5

• Where is the weakness? (which muscles/limb)
• Which reflexes are depressed? → LMN signs
• Which reflexes are brisk? → UMN signs

Question 6

What is cervical myeloradiculopathy?

Answer 6

A condition where a cervical disc or lesion compresses both the nerve root and the spinal cord.

Question 7

What signs are seen at the level of the lesion?

Answer 7

LMN signs – weakness, atrophy, fasciculations, depressed reflexes in muscles supplied by the affected root.

Question 8

What signs are seen below the level of the lesion (cord compression)?

Answer 8

UMN signs – spasticity, brisk reflexes, Babinski sign, clonus.

Question 9

What is the usual cause of cervical myeloradiculopathy?

Answer 9

Disc impinging on the spinal cord.

Question 10

What is an intramedullary lesion?

Answer 10

A lesion inside the spinal cord that causes compression of the cervical cord pyramidal system.

Question 11

Why is sacral sparing seen in intramedullary cervical cord lesions?

Answer 11

Because the lesion is central, sparing the outermost tracts that project to sacral areas.

Question 12

What happens with a lesion in the conus medullaris?

Answer 12

• Can cause spinal cord and nerve root involvement
• Presents with both upper and lower motor neuron signs

Question 13

What are the typical features of a cauda equina lesion?

Answer 13

• Back pain
• Mild weakness in feet
• Bladder symptoms (lower motor neuron type)
• Usually affects S3–S5 areas, sparing L1–L2

Question 14

How do you assess cauda equina lesions?

Answer 14

• Test sensation on back of the leg (S2)
• Ankle jerks, tone, and power (S1/S2)

Question 15

What bladder dysfunction is seen with upper motor neuron lesions (e.g., conus medullaris)?

Answer 15

Spastic bladder → frequency and urgency

Question 16

What bladder dysfunction is seen with lower motor neuron lesions (e.g., cauda equina)?

Answer 16

Flaccid bladder → overflow obstruction

Question 17

What are the clinical features of a central disc herniation affecting S3–S5?

Answer 17

• Lower motor neuron (LMN) bladder → flaccid, overflow incontinence
• Minimal motor weakness in the legs
• May have saddle sensory loss
• Often preserves leg strength and reflexes because L1–L2 roots are spared

Question 18

What are the typical signs of myeloradiculopathy?

Answer 18

Mixed upper and lower motor neuron signs

Question 19

How do cervical cord lesions present?

Answer 19

• Arms: LMN signs (weakness, atrophy, fasciculations)
• Legs: UMN signs (spasticity, hyperreflexia, Babinski)

Question 20

How do thoracic/lumbar cord lesions present?

Answer 20

• Arms: usually normal
• Legs: UMN ± LMN signs (depending on root involvement)

Question 21

What are the common causes of myeloradiculopathy?

Answer 21

• Disc disease: wear & tear at weak spots (cervical and lumbar cord)
• Infections: e.g., TB meningitis (look for gibbus deformity on spine)
• Metabolic: Vitamin B12 deficiency

Question 22

What type of motor and sensory signs are seen in acute/chronic inflammatory demyelinating polyneuropathy?

Answer 22

Only lower motor neuron (LMN) signs, with mainly motor weakness; sensory symptoms are milder.

Question 23

How is acute vs chronic inflammatory demyelinating polyneuropathy differentiated?

Answer 23

• Acute (AIDP/GBS): develops over days
• Chronic (CIDP): progresses over >8 weeks

Question 24

What is the typical reflex pattern in GBS/CIDP?

Answer 24

Areflexia (absent reflexes)

• Even with mild weakness, absent reflexes indicate demyelinated sensory afferents

Question 26

Why might a patient have 3/5 power but absent reflexes?

Answer 26

Because afferent sensory fibers are demyelinated → reflex arc is impaired, even if motor efferents are only mildly weak

Question 27

What are early clinical features of GBS/AIDP?

Answer 27

• Tingling in nerves, often starting in the morning • Mild weakness developing over hours to days • Rapidly progressive paralysis possible → ventilator may be required

Question 28

What are the key features of motor-only proximal weakness?

Answer 28

• Weakness is proximal (shoulders, hips) • Mainly motor, minimal sensory involvement

Question 29

What are the common causes?

Answer 29

• Inflammatory myopathies (e.g., myositis) • Drug-induced (e.g., statins) • Infections (e.g., HIV-associated myopathy)

Question 30

How does onset and progression vary?

Answer 30

• Rapid and painful: drug-triggered or inflammatory • Slower progressive: may have systemic involvement

Question 31

What investigations are important?

Answer 31

Creatine kinase (CK) levels and specialist referral • Note: Some patients may have normal CK levels despite myopathy

Question 32

What type of weakness is seen in Myasthenia Gravis?

Answer 32

Motor-only weakness with a fatigable component; no sensory loss.

Question 33

What are common early complaints in MG?

Answer 33

• Fatigue with chewing (jaw feels tired) • Diplopia (double vision), often worse in the evenings • Ptosis (drooping eyelids) • May notice weight loss due to difficulty eating

Question 34

What is the hallmark feature of MG weakness?

Answer 34

Fatigable weakness → worsens with activity, improves with rest.

Question 35

Which muscles are commonly affected in MG?

Answer 35

• Bulbar muscles: chewing, swallowing, speech • Ocular muscles: extraocular muscles → diplopia, ptosis • Limb muscles: proximal weakness (less prominent early)

Question 36

What is the Ice Test for Myasthenia Gravis?

Answer 36

• Place ice in a plastic bag on one eyelid for 2 minutes. • Cooling inactivates cholinesterase, reducing breakdown of acetylcholine (ACh) at the neuromuscular junction. • Positive test: temporary improvement of ptosis or ocular weakness.

Question 37

Is all ptosis due to Myasthenia Gravis (MG)?

Answer 37

No – history and clinical context are crucial.

Question 38

What historical features suggest MG-related ptosis?

Answer 38

• Fluctuating ptosis (worse with fatigue, later in the day) • Patient complains of eyelid drooping or diplopia

Question 39

What features suggest chronic or non-MG ptosis?

Answer 39

• Patient has obvious ptosis but does not complain • May be associated with sensory neuropathy • Suggests a long-standing or congenital problem

Question 40

What can tongue examination reveal in motor weakness?

Answer 40

Wasting of the tongue can indicate LMN involvement.

Question 41

What features suggest fatigue or exhaustion rather than primary weakness?

Answer 41

• Patient reports fatigue even in the morning on waking → may imply insomnia or functional fatigue • Inability to perform minor tasks (e.g., holding a toothbrush or pen) • Disconnect between reported weakness and objective findings → consider functional or non-organic cause

Question 42

What is give-in weakness in functional weakness?

Answer 42

• When a patient cannot raise the affected arm alone, but can activate it when concentrating on the other arm • Indicates non-organic/functional weakness

Question 43

What is the underlying issue in functional weakness?

Answer 43

It’s a “software problem,” not a hardware problem: • Subjective functional deficits are incongruent with objective signs • Patient cannot properly activate muscles despite intact nervous system

Question 44

What is a diagnostic test for functional leg weakness?

Answer 44

Hoover’s test – assesses involuntary activation of hip extensors when contralateral leg is lifted.

Question 45

What should be explored in functional weakness?

Answer 45

• Sleep patterns • Anxiety or emotional stress • Timing and onset of symptoms

Question 46

How does the brain contribute?

Answer 46

Emotional brain circuits overload and interfere with motor activation circuits, leading to weakness or abnormal movements (e.g., strange walks).

Question 47

What fibers are involved in the reflex arc?

Answer 47

• Sensory afferent: large myelinated fibers (fast) → carry stretch information • Pain fibers (C fibers, slow) → not part of the reflex arc • Motor efferent: must have at least 3/5 power to see a reflex

Question 48

What does it indicate if a patient has 4/5 power but absent reflexes?

Answer 48

There is likely a problem with large myelinated afferent fibers, e.g., demyelination.

Question 49

Key clinical features of acute inflammatory demyelinating polyneuropathy (AIDP/GBS):

Answer 49

• Progressive sensory symptoms: pins and needles in feet • Proximal weakness develops • Reflexes absent • Rapid deterioration: most occurs in first 48 hours • Timeline: • <4–8 weeks: acute phase • 8 weeks: chronic phase (CIDP)

Question 50

How to distinguish acute vs chronic neuropathy?

Answer 50

• Acute: develops over days to weeks, often inflammatory • Chronic: progresses over months to years, often degenerative

Question 51

What are the main causes of weakness?

Answer 51

• Inflammatory • Vascular • Metabolic (including diabetic complications, porphyria, Wilson’s disease)

Question 52

What metabolic conditions can cause weakness?

Answer 52

• Diabetic complications (e.g., neuropathy) • Porphyria • Wilson’s disease

Question 53

A patient complains of severe neck pain radiating down the arm. What could be the likely cause?

Answer 53

Cervical spine wear and tear or a herniated disc.

Question 54

If a patient has a C5 lesion, which muscles are affected?

Answer 54

• Deltoid muscle • Biceps

Question 55

What reflexes would be affected in a C5 lesion?

Answer 55

Biceps reflex would be weak (LMN sign)

Question 56

What reflex changes would you see at C7 in the same patient?

Answer 56

• Brisk reflexes (UMN sign) • Legs would also show UMN signs

Question 57

How does upper motor neuron (UMN) weakness typically present in the arms?

Answer 57

• Flexors stronger than extensors (claw arm) • Hands weaker than shoulders

Question 58

How does UMN weakness present in the legs?

Answer 58

• Extensors stronger than flexors (extended leg) • Hips stronger than feet

Question 59

What pattern of weakness would suggest a combination of C5 lesion and UMN involvement?

Answer 59

• Weak biceps and deltoid (LMN at C5) • Brisk reflexes at C7 and in the legs (UMN signs) • Flexor muscles in arms relatively stronger than extensors • Extensor muscles in legs relatively stronger than flexors