Principles of neuromuscular disease - READING Flashcards
What type of neuromuscular disease is polyradiculoneuritis?
ACUTE GENERALISED NEUROMUSCULAR DISEASE
- Neuropathy
o Inflammatory
Describe polyradiculoneuritis
- Group of inflammatory diseases which affect nn roots and/or peripheral nn
- AETIOLOGY: immune-mediated or infectious disease, attach on peripheral nn or nn roots axonal degeneration and some demyelination
What type of neuromuscular disease is fulminant MG?
- ACUTE GENERALISED NEUROMUSCULAR DISEASE: - Juntionopathy - Idiopathic/paraneoplastic
- CHRONIC GENERALISED NEUROMUSCULAR DISEASE - Junctionopathy
- (FOCAL FORM) ACUTE FOCAL NEUROMUSCULAR DISEASE - junctionopathy - myasthenia gravis (focal)
- (FOCAL FORM) CHRONIC FOCAL NEUROUSCULAR DISEASE - neuropathy - junctionopathy
Describe fulminant MG
• Fulminant MG is the least common subtype of acquired MG (
What type of neuromuscular disease are botulism and tick paralysis?
ACUTE GENERALISED NEUROMUSCULAR DISEASE - Junctionopathy - toxic
Describe botulism
- Flaccid neuromuscular paralysis d/t clostridial neurotoxin
- Symmetrical ascending weakness, death from respiratory paralysis. No changes in consciousness
- Ingestion of carrion or raw meat
Describe tick paralysis
- Causes paralysis in dogs (and cats in Australia) produced by neurotoxin generated by some strains of certain spp of tick
- Flaccid afebrile ascending motor paralysis and progressive respiratory failure
What type of neuromuscular disease is hypocalcaemia?
ACUTE GENERALISED NEUROMUSCULAR DISEASE - Junctionopathy - Metabolic
Describe hypocalcaemia
- Most CS are associated with increased neuromuscular tissue excitability
- Mm trembling, twitching, fasciculation, occasional seizure
- Respiratory arrest is a possible acute presentation
- Possible causes: low concentrations of binding protein, chronic renal failure, puerperal tetany, acute pancreatitis
What type of neuromuscular disease are hypokalaemia and exertional rhabdomyolysis?
ACUTE GENERALISED NEUROMUSCULAR DISEASE - myopathy - metabolic
Describe hypokalaemia
- CS when serum [K+] falls below 2.5-3mmol/l
- Cause – excess loss or reduced intake
- CS –lethargy, fatigue, mm pain, crouched gait, ventroflexion of neck
- Burmese cats - hereditary (hypokalemic polymyopathy)
Describe exertional rhabdomyolysis
- Usually affects athletic and working dogs (Greyhounds and Sled dogs)
- Results from extreme mm work to point that mm cells are damaged secondary problems (range from minor mm pain to death)
- Few references in dogs, well documented in horses
- 3 categories: hyperacute exertional rhabdomyolysis (extreme stress with generalised mm pain), acute exertional rhabdomyolysis (dogs are distressed after race and painful when palpated), subacute rhabdomyolysis (dogs show suboptimal performance)
What type of neuromuscular disease are immune-mediated polymyositis and paraneoplastic polymyositis?
CHRONIC GENERALISED NEUROMUSCULAR DISEASE - Myopathy - Inflammatory
Describe immune-mediated polymyositis
Diffuse inflammation of skeletal mm
Large breed adult dogs most commonly (many GSDs, Boxers, Newfoundlands)
CS – weak, lame, reluctance to exercise, stiff gait, exercise related progression of weakness, mm pain on palpation, mm atrophy, regurgitation d/t megaoesophagus
Responsive to immunosuppressive therapy
Describe paraneoplastic polymyositis?
Usually related to auto-immune stimulation
Frequency b/w neoplasia and this association is unknown
Paraneoplastic MG strongly associated with presence of thymic disease.
What type of neuromuscular disease are centronuclear myopathy, inherited myopathy, fibrotic myopathy (gracilis/ semitendinosus myopathy) and muscular dystrophy?
CHRONIC GENERALISED NEUROMUSCULAR DISEASE - Myopathy - Non-inflammatory
Describe centronuclear myopathy
Labrador retriever puppies
Variable signs
Genetic test for mutation in PTPLA gene and mm biopsy to confirm diagnosis
Tx – none specific, nursing to stabilise by one year old
Describe inherited myopathy
Young Great Danes
Generalised weakness and exercise intolerance, stiff gait
Poor prognosis
Pathophysiology: mm pathology compromised mm function atrophy CS
Describe fibrotic myopathy (gracilis / semitendinosus myopathy)
Horses – adult quarterhorse and stockhorse
Trauma to mm restricted movement, abnormal gait, decreased mm mass
Tx – sx excision of affected tissue and tenotomy
Describe muscular dystrophy
d/t low amounts of dystrophin progressive mm degeneration
usually Golden Retrievers, can be any breed
Duchenne is the most common form in canines
Males usually because X linked recessive
CS from 6-8 weeks of age
Research into Stem Cell therapy
What type of neuromuscular disease are trigeminal neuropathy and facial neuropathy?
ACUTE FOCAL NEUROMUSCULAR DISEASE - Neuropathy - Idiopathic
Describe trigeminal neuropathy
- Can be d/t infiltrating neoplasia
- CN 7 and SNS may also be involved
- CS usually unilateral termporalis and masseter mm ipsilateral to lesion
Describe facial neuropathy
• Paresis or paralysis is most common abnormality seen with facial nerve disease which can occur as an idiopathic condition (especially Cocker Spaniels) as a result of OM/ OE, with trauma and with tumour of middle ear canal
What type of neuromuscular disease are brachial plexus avulsion, femoral nerve injury, sciatic nerve injury and caudal nerve (tail- pull injury)?
ACUTE FOCAL NEUROMUSCULAR DISEASE - Neuropathy - Trauma
Describe brachial plexus avulsion
- d/t trauma, often RTA
- Neurological deficits apparent immediately following injury. Neurogenic atrophy takes 7-10d to develop.
- CS: complete absence of limb function, dropped elbow with carpal flexion, affected limb looks longer, complete absence of sensation in distal limb
- Partial Horner’s in 55% cases
- Brachium advanced when dog is walking
Describe femoral nerve injury
- Uncommon as isolated peripheral lesion since nerve well protected by mm
- D/t pressure on medial thigh
- CS: unable to extend stifle, non-weight bearing, no patellar reflex, decreased skin sensation medial thigh, stifle, lower limb and quadriceps atrophy
Describe sciatic nerve injury
- d/t pelvic, lumbar and sacrococcygeal fractures, foraminal stenosis, sx in pelvic and perineal area and others
- CS: lameness or LMN paresis
Describe caudal nerve (tail-pull) injury
- Often with pelvic trauma, secondary to RTA
- Accompanied by damage to nerve to tail, bladder, perineum and anus (L4-S3)
- Various CS: local hyperaesthesia, flaccid tail paralysis, swelling around tail base, dribbling urine
What type of neuromuscular disease is ischaemic neuromyopathy?
- ACUTE FOCAL NEUROMUSCULAR DISEASE - neuropathy/myopathy - vascular
- ACUTE
Describe ischaemic neuromyopathy
- d/t thromboembolism (cats with cardiomyopathy – HCM in cats mean age 5yo, DCM in older cats, also hyperthyroidism and hypercoagulable conditions
- CS: depend on location
Describe focal myasthenia gravis (MG)
- Only affects extraocular mm, oesophagus and mm innervated by CN 5, 7 & 9
- Present with laryngeal, pharyngeal, facial and oesophageal dysfunction (vs. generalised form which present with non-ambulatory tetraparesis and dyspnoea)
What type of neuromuscular disease are masticatory muscle myositis (MMM) and extraocular myositis?
ACUTE FOCAL NEUROMUSCULAR DISEASE - myopathy - inflammatory
Describe masticatory muscle myositis (MMM)
- Common autoimmune inflammatory myopathy
- Focal inflammation of digastricus, temporalis, pterygoid, masseteric as masticatory mm are composed of a specific type of myofibres (type 2M) and CD8+ TC initiate their destruction via autoantibodies.
- Large dog breeds, median age 2 years
- 2 forms: acute and chronic
Describe extraoxular myositis
- Larger breed dogs, especially Golden Retriever
- Females, 6-24 months old
- Relatively uncommon
Describe recumbency / compartment syndrome
- When the tissue pressure within a closed mm compartment exceeds the perfusion pressure and results in mm and nn ischaemia
- Usually subsequent to trauma (e.g. fracture)
What type of neuromuscular disease is degenerative lumbosacral stenosis (DLSS)?
CHRONIC FOCAL NEUROMUSCULAR DISEASE - Neuropathy - Degenerative
Describe degenerative lumbosacral stenosis (DLSS)
- Common cause of cauda equina syndrome
- Relatively frequent neuro condition of older dogs
- Applies to syndromes affecting spinal cord segments, spinal nerve roots, spinal nerves (sciatic nerve perineum, bladder, urethral and anal sphincters, tail)
- Lumbosacral disease encompasses any pathologic condition that affects the region of the spinal cord segments that contribute to the sciatic nerve and sacral and caudal nerves. Cauda equina syndrome implies pathologic conditions that affect the last several pairs of spinal nerve roots.
What neoplasias can cause chronic focal neuromuscular disease - neuropathy - neoplasia?
- peripheral nerve sheath tumour
- lymphoma
- meningioma
Describe peripheral nerve sheath tumour
- 25% of canine nervous system tumours
- A type of intra-dural extra-medullary tumour
- Commonly middle to low cervical nerve roots and brachial plexus. Sometimes also trigeminal nerve, thoracic nerves and lumbosacral plexus. Thoracic limb often affected
- CS: peripheral nn deficits and mm atrophy
- Tumour of nn sheath interruption of nn conduction loss of function of target organ mm atrophy where skeletal mm affected
Describe CNS lymphoma
- One form is CNS form
* Commonest haemopoietic neoplasm (8-10% of all canine malignant
Describe meningioma
- Commonest brain neoplasm
- Usually benign, slow growing
- Mostly on floor of cranial cavity, over convexitis of cerebral hemispheres or over cerebellum and olfactory lobes
- CS: seizures, insidious onset neuro signs, focal CS
List some chronic focal neuromuscular diseases causing myopathies
o Inflammatory: Masticatory myositis ad Extraocular myositis –
o Non-inflammatory: Fibrotic myopathy (gracilis/ semitendinosus myopathy)
