Peripheral neuropathies

Question 1

Segmental demyelination

Answer 1

Results form a dysfunction of the Schwann cells or a damage to the myelin sheath.
The axon is not involved at least initially.
It is describes as Primary Demyelinating Neuropathy.

Question 2

Axonal degeneration

Answer 2

Reflects direct injury to the axon or to the neuronal cell body.
If the cell body is damaged necrosis follows.
If the distal end of axon is the primary site of injury, degeneration is followed by axonal regeneration and re-innervation of a muscle.
If the cause is removed recovering is possible. This must occur before the dying-back degeneration involves the proximal axon and cell body.
Described as secondary demyelinating neuropathy.

Question 3

Neuropathy

Answer 3

Consist of necrosis of the cell body and axon simultaneously.
Recovery of function is unlikely, unless nearby neurons take over the affected area.

Question 4

Wallerian degeneration

Answer 4

Consists in the axonal degeneration that occurs distal to the site of damage.
If sufficiently distal, the nerve may regenerate
The Schwann cells proliferate in preparation to ensheath the axon.

Question 5

Axonal neuropathy

Answer 5

Axonal degeneration predominates

Question 6

Demyelinating neuropathy

Answer 6

Segmental demyelination predominates

Question 7

Clinical features of peripheral neuropathies

Answer 7

Muscle weakness
Muscle atrophy
Sensory loss
Paraesthesia
Pain
Autonomic dysfunction (blood pressure, hear rate, visceral functions, temperature regulation)
Motor, sensory and autonomic functions may be equally or predominantly affected
Neuropathies may be acute (days/weeks), subacute (weeks/months), and chronic (months/years)

Question 8

Mononeuropathy

Answer 8

Only one nerve

Question 9

Multiple neuropathy

Answer 9

Several assymetrical nerves are involved (mononeuritis multiplex)

Question 10

Polyneuropathy

Answer 10

Generalised symmetrical involvement

Question 11

Radiculopathy

Answer 11

Nerve root involvement

Question 12

POlyradiculoneurpathy

Answer 12

Nerve roots and peripheral nerves

Question 13

Bells palsy

Answer 13

Idiopathic facial nerve palsy.

Cranial mononeuropathy affecting the cranial nerve (VII)

Question 14

Classifications of polyneuropathies

Answer 14

Immune-inflammatory neuropathies, infectious polyneuropathies, heredity neuropathies and acquired, metabolic and toxic neuropathies.

Question 15

Clinical features of polyneuropathies

Answer 15

Depends on the number of sites, speed of onset, causes, and whether motor, sensory or combined motor-sensory.
Commonest is sensory loss with muscle wasting and weakness in a ‘glove and stocking’ distribution.