Polyneuropathies

Question 1

Sensorimotor differentials

Answer 1

Diabetes (generally more sensory)
Vitamin deficiency
Alcohol
Endocrine - hypothyroidism,, renal failure, liver failure
Vasculitis
Iatrogenic
- chemotherapy (cisplatin, vincristine)
- amiidarone
- phenytoin
- infection - HIV, leprosy, CMV
- anti-TB - isoniazid, ethambutol
- antibiotics - metronidazole, nitrifurantoin

Question 2

Predominantly motor

Answer 2

Inflammatory
- GBS
- CIDP (polyradiculioathy)
- multifocal mononeurooathy with conduction block
- paraprotein associated (MGUS, MM)
Toxins (heavy metals)
Diabetic amyotrophy
Inherited
- inherited distal motor neuropathy
- spinal muscular atrophy

Question 3

Sensory neuronopathies

Answer 3

Paraneoplastic
Sjogrens
Friedrichs ataxia
Drugs Ed chemotherapy

Question 4

Mononeuritis multiplex

Answer 4

Vasculitis
- (primary) churg-strauss, wegeners, PAN, microscopic polyangitis
- secondary (RA, SLE, vasculitis secondary to hep B and C
Sjogrens syndrome
Sarcoidosis
Hep C

Question 5

Thickened nerves

Answer 5

Hypertrophic Charcot Marie tooth
CIDP
Leprosy
Amyloidosis
Neurofibromatosis
Acromegaly

Question 6

1st stage investigation

Answer 6

Bloods (fbc, renal, liver, hba1c, thyroid, vitamins,

Urinalysis, ESR

Question 7

2nd stage investigations

Answer 7

Nerve conducting studies and EMG
Serum free light chains and immunoglobulins
Vasculitis screen (RhF, ANA, ANCA, anti-Ro and -La
CXR

Question 8

3rd stage

Answer 8

LP
Immunology (HIV, antineuronal antibodies (anti-hu, anti-yo), antigliadin antibodies, serum ACE
Test for sjogrens (schirmers teat, salivary flow rate, labial gland biopsy
Look for malignancy
Molecular genetics (most related to Charcot Marie tooth, multiple genetic causes of this autosomal dominant condition. Most common cause is abnormality is peripheral nerve myelin protein 22 gene duplication

Question 9

Differential diagnoses of predominantly motor pokyneuropathy

Answer 9

Neuromuscular disorders
- myasthenia gravis (complex opthalmoplegia, fatiguabiliry, Ptosis)
- lambert-Eaton syndrome (associated with SCLC. Chachexia, post-titanic potentiation (increasing reaction to reflexes))
Distal myopathy
- myotonic dystrophy(frontal balding, facial muscle wasting, cardiac pacemaker, learning disabilities, percussion myotonia
- inclusion body myositis (finger, wrist, knee and dorsiflexors most affected. ‘Scalloping’ of hands as a result. Difficulty writing may be first sign