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Flashcards in neuromuscular Dz Deck (30):

What potential stages of the neuromuscular system may be affecte?

- neuropathy
- junctionopathy
- myopathy
> many different diseases give very similary presentations


Cardinal signs of neurouscular dz

> weakness (generalised or focal) and excercise intolerance
> change in morphology
- muscle atrophy (generalised or focal)
- muscle hypertrophy (generalised or focal)
- limb/skeletal deformities
- gait abnormalities annd/or lameness (palmigrade/plantigrade stance esp neuropathies)
> change in function
- dysphagia (weak gag?)
- regurgitation
- megaoesophagus
- laryngeal paralysis
- dyspnoea
- dysphonia (esp. neuropathies)
- myalgia
- weak palpebral


How does the proportion of striated muscle differ between species?

100% dog and human
80% cat
65% horse
30% pig


How may weakness manifest?

- tremors
- plantigrade/palmigrade stance
- limbs under centre of gravity, very straight
- knuckling


Defining the system.. Ddx of weakness?

> CV/resp?
- hypotension
- arrhythmias
- hypoxaemia
> metabolic/systemic
- hypoglycaemia
- anaemia
- sepsis
> paraneoplastic
- thymoma -> myasthenia gravis
> neuro


How can cv/resp casues be ruled out?

- hx
- PE (auscultation, pulse rate/quality)
- |Blood pressure
- thoracic rads
- echo


How can metabolic/systemic causes be ruled out?

- hx
- PE
- haematology
- serum biochem
- electrolyte analysis
- blood gas analysis


Which electrolytes may be imbalanced -> weakness?

- hypokalamia (low head carriage and stiff limbs characteristic)
-hypocalcaemia (tremors)
- hypERmagnesaemia


How can neuro causes be refined?

> 1* neuro dz
- neuromuscular
> dysfunction 2* to
- CV/resp
- metabolic/systemic
= investigations (Hx, PE, Neuro exam)


How may neuromuscular dz present other than weakness/loss of function/change in morphology?

- self mutilation if sensory only affected (some dz)


How can localision within the neuromuscular region be defined?

VERY DIFFICULT!!! - broad generalisations...
> neuropathy
- v/absent spinal reflexes and postural reactions
- platigrade/palmigrade stance
- reduced/absent muscle tone
+- neurogenic atrophy
> junctionopathy
- normal/reduced spinal reflexes and postural reactions
+- exercise intolerance
> myopathy
- spinal reflexes and postural reactions normal
- generalised weakness
- +- myalgia


Generalised neuromuscular disease indicates what localisation..

Either multiple focal lesions SC (C6-T2 and L4-S3) - RARE!
or generalised neuromuscular (most ilekly)


Something about bear skin with 4 limbs generalised. focal neuromuscular UMN/LMN?? EMAIL!!



How can the lesion be localised neuron/NMJ/muscle?

> muscle enzymes
- CK
> urinalysis
- myoglobinuria
= all these would suggest myopathy


What are EMGs?

- electromyography
- needle inserted into muscle belly, measures difference between mid and outside needle
- small waveform seen on insertion of needle
- then should be very little activity
> will not determine aetiology but will be abnormal (see waveforms) if disease affects muscle or LMN
- can help differentiate disuse and denervation atrophy
- map distribution of lesions


What are the 2 main types of electrodiagnostics?

> nerve conduction studies
- measure velocity of impulse through neuron (may indicate myelination defect)
- measure time taken for conduction through wole neuro/NMJ/muscle (by subtracting time between waveforms to pass 2 needles)
- assess axon function (amplitude of wave)
> EMG electromyography (mentioned prev)


How are diagnostic tests chosen?

prioritise based on Ddx (6 finger rule)
- localisation
- signalment
- onset
- progression
- symmetry
- pain


Which are the most important attributes of the disease process to limit Ddx with neuromuscular dz?

- onset and localisation
> acute generalised
> acute focal
> chronic generalised
> chronic focal


Look up all highlighted ddx as suggested further reading



Most common cause of acute focal NMD?



Most common cause of chronic generalised NMD?

breed related


3 pathologies that serology can be carried out for?

> myasthenia gravis
- nicotinic acetylcholine R Ab titre
> masticatory myositis
- 2M myofibre Ab titre
> infectious agents
- toxoplasma [cats], neospora [dogs]


What is extraocular/masticatory myositis and how can it be diagnosed?

- consistent clinical signs and imagine, NOT Dx on imaging alone
- immune mediated attack of the "M myofibres (masticatory) not sure about extraocular


What further diagnostic tests can be used to define the lesion?

- muscle biopsy
- CSF analysis (can SOMETIMEs change wih nerve root disease) usually shows central disease
- nerve biopsy


If generalised decreased reflexes seen, How can neuro and muscle athologies be differenttied?

CK to r/o muscle
- if reflexes lacking most likely neuro


How are purebred animals workedup slightly differently?

- look for predisposiions if small genetic pool!


eg. of a breed speicifc predispose disease?

> Bengal polyneuropathy
- recurrent relapsing/remitting de-re-myelination
- non-painul
- resolves spontaneously


Most common cause of polyneuropathy in cats?

- diabetic polyneuropathy


How do reflexes of cats compare to dogs?

More brisk


What type of tumour do peripheral nerve sheath tumours behave like?

Soft tissue sarcoma