Peripheral Nerve and Muscle Disease

Question 1

What is a polyneuropathy?

Answer 1

Generalised involvement of multiple peripheral nerves
‘Length dependant’ (more distal nerves are affected first)

Question 2

Surgical sieve causes for polyneuropathy

Answer 2

Vasculitis
Idiopathic
Toxic (alcohol, heavy metals, chemotherapy)
Autoimmune (Guillian Barre)
Medications: nitrofurantoin, isoniazid
Inflammatory (CIDP)
Neoplastic (myeloma, paraneoplastic syndrome)
Systemic illness (amyloidosis, CKD, hypothyroidism)

Diabetes Mellitus (most common cause)

Question 3

Investigation for polyneuropathy

Answer 3

Nerve conduction studies (electromyography and nerve conduction studies)

Question 4

What a radiculopathy?

Answer 4

Symptoms or impairments related to a spinal root

Question 5

What is a mononeuropathy?

Answer 5

Damage or dysfunction of a single peripheral nerve

Question 6

What is polymyositis?

Answer 6

inflammatory disorder causing symmetrical, proximal muscle weakness

Question 7

Pathophysiology of polymyositis

Answer 7

thought to be a T-cell mediated cytotoxic process directed against muscle fibres
may be idiopathic or associated with connective tissue disorders
associated with malignancy

Question 8

Clinical features of polymyositis

Answer 8

proximal muscle weakness +/- tenderness
Raynaud’s
respiratory muscle weakness
interstitial lung disease (e.g. fibrosing alveolitis or organising pneumonia)
dysphagia, dysphonia

Question 9

Investigation results polymyositis

Answer 9

elevated creatine kinase
other muscle enzymes (lactate dehydrogenase (LDH), aldolase, AST and ALT) are also elevated in 85-95% of patients
EMG
muscle biopsy
anti-synthetase antibodies (anti-Jo-1 antibodies are seen in pattern of disease associated with lung involvement, Raynaud’s and fever)

Question 10

What is dermatomyositis?

Answer 10

Polymyositis +

photosensitive
macular rash over back and shoulder
heliotrope rash in the periorbital region
Gottron’s papules - roughened red papules over extensor surfaces of fingers
‘mechanic’s hands’: extremely dry and scaly hands with linear ‘cracks’ on the palmar and lateral aspects of the fingers
nail fold capillary dilatation

Question 11

Features of duchennes muscular dystrophy

Answer 11

progressive proximal muscle weakness from 5 years
calf pseudohypertrophy
Gower’s sign: child uses arms to stand up from a squatted position
30% of patients have intellectual impairment

Question 12

Investigation for duchennes

Answer 12

Genetic testing