Mononeuritis multiplex Flashcards
What is mononeuritis multiplex?
A fancy way of saying sensory and motor periperal neruropathy in 2+ nerves that are not connected
It’s not actually a distinct disease entity but a group of disorders
How might mononeuritis multiplex present?
Sensory and motor deficits in the distribution of specific nerves
Asymmetrical to begin with
Numbness, tingling, abnormal sensation, burning pain, lack of controlled movement
What is the most common cause of mononeuritis multiplex?
Vasculitis
Causes of mononeuritis multiplex
Vasculitis = most common
But… loaaaaads of things can cause it
Infections: Lyme disease, Hep B, HIV, AIDS
Chronic conditions: DM, amyloidosis
Cancer: lymphoma, carcinoid tumour
Haem: Churg-Strauss (clustering of WBCs)
33% cases are idiopathic
Which conditions can cause mononeuritis multiplex?
Vasculitis - most common
DM
SLE
Paraneoplastic syndromes
Amyloidosis
Pathophysiology of mononeuritis multiplex
Most commonly due to nerve ischaemia secondary to vasculitis
Necrotising arteritis occurs due to inflammation and therefore the vasa nervorum which supplies the nerve is unable to nourish the nerve
This leads to randomly distributed ischaemia along the course of the nerve
Examination for mononeuritis multiplex
Sciatic nerve examination: pain and numbness in back of leg and buttock
Femoral nerve examination: pain and numbness in front of leg
Common peroneal nerve: foot drop
Axillary nerve: deltoid/ teres minor paralysis (can’t externally rotate shoulder), sargeant stripe numbness
Radial, median, ulnar nerves
Where is most commonly affected in mononeuritis multiplex?
Braches of the sciatic nerve
What would make systemic vasculitis as the cause of mononeuritis multiplex more probable?
Systemic symptoms: fever, night sweats, joint swelling, abdo pain, pulmonary symptoms
Management of mononeuritis multiplex
Look for a cause and treat it
PT to prevent contractures and maintain strength
Investigating mononeuritis multiplex
Electromyogram
FBC: 50% patients with systemic vasculitis have anaemia and leukocytosis
ESR + CRP: raised in vasculitis
Blood glucose: DM
Tests for other suspected causes
Patient has pain/ loss of sensation in various unrelated areas and you suspect mononeuritis multiplex - they also have large non-healing mouth ulcers - thoughts?
Systemic lupus erythematous - causes large mouth ulcers
Patient presenting with sensory and motor function loss in no particular pattern - thoughts?
Mononeuritis multiplex
When multiple, anatomically unrelated nerves are dysfunctional/ associated with pain - what should you think?
Most likely a systemic condition as opposed to trauma/ compression
Difference in aetiology of mononeuropathy and mnoneuritis multiplex?
Mononeuropathy: most commonly due to compression/ trauma
Mononeuritis multiplex: most commonly due to systemic vasculitis
