Neuromuscular disease - small animal Flashcards Preview

Neurology > Neuromuscular disease - small animal > Flashcards

Flashcards in Neuromuscular disease - small animal Deck (33)
Loading flashcards...
1
Q

What are the 3 main types of neuromuscular system disorder?

A
  • neuropathy
  • junctionopathy
  • myopathy
    (i. e. neuromuscular = peripheral nervous system and mm)
  • -> many different diseases with very similar presentations
2
Q

What are 2 cardinal signs of neuromuscular disease?

A
  • weakness (generalised or focal)

- exercise intolerance

3
Q

When should you suspect a neuromuscular disease?

A
  • CARDINAL SIGNS OF NEUROMUSCULAR DISEASE: weakness (general/focal), exercise intolerance
  • CHANGE IN MORPHOLOGY: mm atrophy (general/ focal), mm hypertrophy (general or focal), limb/ skeletal deformities, gait abnormalities and/or lameness
  • CHANGE IN FUNCTION: dysphagia, regurgitation, megaoesophagus, laryngeal paralysis, dyspnoea, dysphonia, myalgia
  • increase your suspicion the more CS there are
4
Q

Define myalgia

A

mm pain

5
Q

How do weak animals sit?

A

with all limbs under their centre of gravity

6
Q

What might a generalised weakness caused by a polyneuropathy present as?

A

generalised tremor

7
Q

System ddx for neuromuscular weakness - 3

A
  • neurological
  • cardiovascular/respiratory
  • metabolic/systemic
8
Q

Cardio/resp causes of weakness

A
  • hypotension
  • arrhythmias
  • hypoxaemia etc
  • TESTS: hx, PE (auscultation, pulse rate/quality), BP, ECG, thoracic radiography, echo.
9
Q

Metabolic/ systemic causes of weakness

A
  • hypoglycaemia
  • anaemia
  • sepsis
    INVESTIGATE: hx, PE, haem, serum biochem, electrolytes, blood gas
10
Q

Which electrolyte disturbances are important in causing weakness?

A
  • HYPOKALEMIA
  • hypocalcaemia (more common in LA than SA)
  • hypermagnesaemia
11
Q

T/F: low head carriage is a typical sign of neuromuscular weakness

A

True

12
Q

Outline neurological causes of weakness

A
  • PRIMARY NEUROLOGICAL DISEASE: neuromuscular
  • DYSFUNCTION SECONDARY TO: cardiovascular/ respiratory, metabolic/ systemic
  • INVESTIGATIONS: hx, PE, neuro exam –> normal or abnormal?
13
Q

CS indicating neuro cause of weakness

A
  • weak palpebral or gag
  • dysphonia
  • plantigrade/ palmigrade (latter especially) stance
  • self-mutilation (sensory)
  • regurgitation/ megaoesophagus
14
Q

List some generalisation to distinguish neuropathy, junctionopathy and myopathy

A
  • NEUROPATHY: reduced/absent spinal reflexes and postural reactions platigrade/palmigrade stance, reduce/ absent mm tone, +/- (neurogenic) atrophy
  • JUNCTIONOPATHY: normal/reduced spinal reflexes and postural reactions, +/- exercise intolerance
  • MYOPATHY: spinal reflexes and postural reactions generally normal, often generalised weakness, +/- myalgia
15
Q

How can you define the location of weakness?

A
  • MM ENZYMES: highly incresed CK, quite increase AST, increased ALT
  • UA: myoglobinuria
16
Q

What is EMG?

A

= electromyography

  • a functional test
  • will not determine aetiolgoy
  • needle/electrode inserted into mm, measures charge b/w inside and outside of needle. Charge should be relatively quiescent with needle in.
  • abnormal if disease affects: mm or LMN
  • USE: distinguish disuse and denervation atrophy and mapping distribution of lesion
17
Q

What is a nerve conduction study?

A
  • to determine if nerve is abnormal or not
  • METHOD: you stimulate nn along its course to mm then record mm contraction
  • Amplitude determined by axons (increase –> increase)
  • Velocity determined by +/- myelin
  • lesions generally either affect either amplitude or veloctity
  • doesn’t allow a final diagnosis
18
Q

What are ddx based on?

A

LSO PSP:

  • Localisation
  • Signalment
  • Onset
  • Progression
  • Symmetry
  • Pain
  • MOST USEFUL = localisation, onset, symmetry
19
Q

What are the 4 main categories of ddx for neuromuscular pain?

A
  • acute generalised
  • acute focal
  • chronic generalised
  • chronic focal
  • select are prioritise diagnostic tests based on this categorisation*
20
Q

Ddx - acute generalised neuromuscular problem

A
  • NEUROPATHY: inflammatory - polyradiculoneuritis
  • JUNCTIONOPATHY - MG (fulminant), botulism, tick paralysis, (black widow, pesticices, drugs), hypocalcaemia
  • MYOPATHY - hypokalaemia, (hyperkalaemic periodic paralysis, hypoadrenocorticism), exertional rhabdomyolysis
21
Q

Ddx - chronic generalised neuromuscular problem

A

Huge ddx, most common are listed

  • NEUONOPATHY: inherited and acquired MND
  • NEUROPATHY: inherited polyneuropathy, diabetic polyneuropathy, chronic inflammatory demyelinating polyneuropathy, potozoal polyradiculoneuritis (Neospora)
  • JUNCTIONOPATHY: MG
  • MYOPATHY: hypokalaemia, immune-mediated polymyositis, paraneoplastic polymyositis, centronuclear myopathy, inherited myopathy, fibrotic myopathy (gracilis, semitendinosus myopathy), muscular dystrophy
22
Q

Ddx - acute focal neuromuscular problem

A
  • NEUROPATHY: trigeminal neuropathy, facial neuropathy, brachial plexus avulsion, femoral nn injury, sciatic nn injury, caudal nn (tail pull) injury, ischaemic neuromyoneuropathy
  • JUNCTIONOPATHY: MG (focal)
  • MYOPATHY: masticatory myositis, extraocular myositis, direct trauma, recumbency/ compartment syndrome, ischaemic neuromyopathy
23
Q

Ddx - chronic focal neuromuscular problem

A
  • NEUROPATHY: DLSS, peripheral nerve sheath tumour, lymphoma, meningioma,
  • JUNCTIONOPATHY: MG (focal)
  • MYOPATHY: masticatory myositis, extraocular myositis, fibrotic myopathy (gracilis/ semitendinosus myopathy)
24
Q

Diagnostic tests to define the lesion

A
  • Haematology
  • biochem
  • ACTH stim?
  • T4?
  • Serology:
    • MG (nicotinic Ach -R Ab titre)
    • Masticatory myositis (2M myofibre Ab titre)
    • Infectious agents (toxoplasma, neospora)
  • Genetic testing (interpret based on CS)
  • Metabolic screening (urine)
  • CSF sample
  • mm biopsy
  • nn biopsy
25
Q

Best imaging modality for spinal cord?

A

= MRI
- best for peripheral nn
- good tissue contrast
(CT - good for enlarged brachial plexus)

26
Q

T/F: disease of nn roots may cause changes in CSF

A

True

27
Q

2 sites for CSF samples

A
  • cisternal

- lumbar

28
Q

Localisation: decreased mm tone, decreased reflexes, both in all 4 limbs

A

= LMN signs so therefore generalised neuromuscular (most likely) or 2 lesions in spinal cord (C6-T2 and L4-S3; rare)

29
Q

How do you determine is a lesion is in brainstem or peripheral?

A
  • Brainstem lesion: affects mentation, postural reactions, CN deficits
  • Even if several CN deficits but mentation, gait and postural reactions are normal, suggests a peripheral lesion most likely
30
Q

Cause - trigeminal neuropathy

A
  • usually idiopathic, possibly neuritis
31
Q

Tx - trigeminal neuropathy

A

Self-resolving in several weeks so tx usually supportive; wet food, symptomatic management

32
Q

Which nn does the gastrocnemius reflex test?

A

femoral and sciatic (n.b. withdrawal is better indicator of sciatic nn problem)

33
Q

Tx - malignant peripheral nn sheath tumour

A
  • this behaves like STS
  • tx for both is sx excision (aggressive)
  • always consider location, if poor location - consider euthanasia