SA Neurology

3 types of ataxia

3 types of ataxia

Proprioceptive Cerebellar Vestibular

Paraparesis/plegia

Pelvic limb weakness/paralysis

Hemiparesis/plegia

Limbs on one side of the body weakened/paralysed

Tetraparesis/plegia

All limb weakness/paralysis

Muscle tone, Spinal reflexed, and muscle atrophy associated with an UMN lesion

Muscle tone = normal/increased Spinal reflexes = normal/increased Muscle atrophy = little, late

Muscle tone, spinal reflexes and muscle atrophy associated with a LMN lesion

Muscle tone = decreased Spinal reflexes = decreased Muscle atrophy = severe, early

Gait, reflexes, and proprioceptive deficits associated with C1-C5 lesion

Gait = ataxia, tetra/hemi-paresis/plegia Reflexes = normal Proprioception = deficits on one side or all limbs

Gait, reflexes, and proprioceptive deficits associated with C6-T2 lesion

Gait = ataxia, hemi/tetra-paresis/plegia Reflexes = decreased in thoracic limbs, normal in pelvic Proprioception = deficits on one side or all limbs

Gait, reflexes, and proprioceptive deficits associated with T3-L3 lesion

Gait = pelvic limb ataxia, paraplegia/paresis Reflexes = normal Proprioception = normal in thoracic limbs, deficits in pelvic

Gait, reflexes, and proprioceptive deficits associated with L4-S1 lesion

Gait = pelvic limb ataxia, para/mono-paresis/plegia Reflexes = normal in thoracic, decreased in pelvic Proprioception = normal in thoracic limbs, deficits in pelvic

Signs of spinal cord lesion in S1-S3

Tail paresis/plegia

Dilated anus and decreased perineal reflex

Flaccid and easy to express bladder

Grading scale for spinal cord injuries

0 = normal

1 = pain, no deficits

2 = ambulatory paresis

3 = non-ambulatory paresis

4 = plegia

5 = no deep pain sensation

Spinal cord segment, motor function and cutaneous sensation of the suprascapular nerve

Spinal cord segment = C6-7

Motor function = shoulder extension

Cutaneous sensation = shoulder

Spinal cord segment, motor function and cutaneous sensation of the musculocutaneous nerve

Spinal cord segment = C6-8

Motor function = elbow flexion

Cutaneous sensation = medial antebrachium, digit 1

Spinal cord segment, motor function and cutaneous sensation of the radial nerve

Spinal cord segment = C7-T2

Motor function = elbow, carpus and digit extension

Cutaneous sensation = cranial antebrachium and foot

Spinal cord segment, motor function and cutaneous sensation of the median and ulnar nerves

Spinal cord segment = C8-T2

Motor function = carpus and digit flexion

Cutaneous sensation = caudal antebrachium and lateral aspect of digit 5

Spinal cord segment, motor function and cutaneous sensation of the obturator nerve

Spinal cord segment = L4-L6

Motor function = hip adduction

Cutaneous sensation = none

Spinal cord segment, motor function and cutaneous sensation of the femoral nerve

Spinal cord segment = L4-L6

Motor function = hip flexion, stifle extension

Cutaneous sensation = medial limb and digit 1

Spinal cord segment, motor function and cutaneous sensation of the sciatic nerve

Spinal cord segment = L6-S2

Motor function = hip extension, stifle flexion, hock and digit movement

Cutaneous sensation = rest of the hindlimb

Pseudohyperreflexia

Increased patellar reflex due to sciatic nerve dysfunction (loss of counter tone)

Ddx for spinal pain in a young dog

Steroid responsive meningitis-arteritis (SRMA)

Discospondylitis

Atlantoaxial subluxation

Canine Chiari malformation (esp. in CKCS)

Ddx for spinal pain in older dogs

Intervertebral disc disease

Discospondylitis

Neoplasia

Lumbosacral stenosis

Pathogenesis of discospondylitis

Infection (usually haematogenous spread, also fb migration or penetrating wound) of intervertebral disc and adjacent vertebral endplates

Signs of discospondylitis

Usually large, intact males young-middle aged

Spinal pain (often lumbosacral junction, thoracolumbar region or caudal cervical region) +/- systemic signs +/- neurological deficits (rare)

Diagnosis of discospondylitis

Radiography (changes take 2-4w to appear) - irregular endplates

Blood/urine culture

Treatment of discospondylitits

Antibiotics for 6-8w (C+S or potentiated penicillin/cephalosporins)

Analgesia (NSAIDs, gabapentin)

Strict rest

Signs of steroid responsive meningitis-arteritis (SRMA)

Severe neck pain

Systemic signs (intermittent) +/- polyarthritis

Diagnosis of steroid responsive meningitis-arteritis

CSF - neutrophilia

Treatment of steroid responsive meningitis-arteritis

Prednisolone +/- other immunosuppressants

Caudal occipital malformation syndrome AKA

Canine chirari malformation

Pathogenesis of canine chiari malformation

Congenital hypoplasia of supraoccipital bone = cerebellar herniation = abnormal CSF movement = syringohydromyelia

Syryngomyelia

Fluid filled cavitation of the spinal cord

Hydromyelia

Dilation of the central canal of the spinal cord

Signs of canine chiari malformation

Usually young CKCS or Brussels griffons

Cervical pain

Persistent scratching

Torticollis (wry neck)

+/- neurological signs

Diagnosis of canine chiari malformation

MRI

Treatment of canine chiari malformation

Conservative NSAIDs, gabapentin

If ineffective, low dose steroids

Furosemide, omeprazole, etc to decreased CSF

Surgical decompression of foramen magnum

Signs of lumbosacral stenosis

Usually large breed, middle aged dogs (esp. males)

Lumbosacral pain

Difficulty jumping and intermittent lameness +/- urinary incontinence

Pathogenesis of lumbosacral stenosis

L7-S1 instability = chronic intervertebral disc herniation = foramenal stenosis due to fibrosis

Diagnosis of lumbosacral stenosis

MRI/CT

Treatment of lumbosacral stenosis

Conservative:

• Strict rest (8-14w)

• NSAIDs/low dose steroids

• Gabapentin

• Epidural steroid injection

Surgical

Ddx for acute paralysis/paresis

Intervertebral disc disease (Hansen type 1)

Traumatic disc extrusion

Fibrocartilaginous embolism (FCE)

Neoplasia (pathological fracture or haemorrhage)

Trauma

2 types of intervertebral disc disease

Hansen type 1 (acute)

Hansen type 2 (chronic)

Hansen type 1 intervertebral disc disease

Herniation of nucleus pulposus through annulus fibrosis

Acute presentation

Hansen type 2 intervertebral disc disease

Annulus fibrosus protrudes into spinal canal

Chronic presentation; Progressive

Diagnosis of intervertebral disc disease

MRI (T2) - darkening/mineralisation of discs

Radiographs/myelography - narrowing of disc space and mineralisation within disc space CT

Treatment of intervertebral disc disease

Conservative (only for type 1): Strict rest for 4-6w

Surgical (if >grade 3 spinal cord injury, or unmanageable pain):

• Decompression (removal of disc)

• Disc fenestration (removal of nucleus pulposus)

Signs of traumatic disc extrusion

Pain at the time (will go away by 24h)

Spinal cord signs

Treatment of traumatic disc extrusion

Physiotherapy

Pathophysiology of fibrocartilaginous embolism

Spinal cord ischemia due to emboli (derived from disc fibrocartilage)

Signs of fibrocartilaginous embolism

Pain at time of injury (gone by 24h)

Signs of spinal cord injury

No disc damage

Treatment of fibrocartilaginous embolism

Physiotherapy

Treatment of spinal fractures

If stable = rest and analgesia

If unstable = surgical

Ddx for progressive paralysis/plegia

Intervertebral disc disease (Hansen type 2)

Neoplasia

Degenerative myelopathy

Myelitis

Congenital vertebral malformations

Wobbler syndrome (dogs)

Classification of spinal neoplasia

Tumour type

Relationship to meninges/spinal cord (extradural, intradural but extramedullary, intradural and intramedullary)

Chronic degenerative radiculomyelopathy (CDRM) AKA

Degenerative myelopathy

Signs of degenerative myelopathy

Gradual progression of pelvic limb ataxia

Not painful

Diagnosis of degenerative myelopathy

Exclusion Genetic tests PM

Prognosis of degenerative myelopathy

Poor

Can prolong life with physiotherapy

Cause of myelitis in dogs

Granulomatous myeloencephalitis

Cause of myelitis in cats

FIP

Treatment of myelitis

Prednisolone +/- other immunosuppressants

What determines the degree of deficits seen with congenital spinal malformations

Degree of kyphosis

Wobbler syndrome in dogs AKA

Cervical spondylomyelopathy

2 forms of wobbler syndrome in dogs

Disc associated

Osseous associated

Disc associated wobbler syndrome in dogs

Middle aged large breeds

Annular fibrosis or ligamentous flavum hypertrophy

Osseous associated wobbler syndrome in dogs

1-4y giant breeds

Osseous proliferation of articular facets or dorsal arch = compression of the spinal cord

Treatment of wobbler syndrome in dogs

Conservative: Strict rest + Steroids (anti-inflammatory dose)

Surgical

Initial work up of a case of weakness/exercise intolerance

Haematology/biochemistry - metabolic causes

Endocrine testing - endocrine causes

Muscle enzymes (ALT, AST, CK) - myopathies

Infectious disease titres (toxoplasma, neospora)

Thoracic radiographs - neoplasia, megaoesophagus

Abdominal U/S - neoplasia

Ddx for peripheral nervous signs with persistent deficits

Peripheral neuropathy

Botulism

Neuroparalytic snake bite

Tick paralysis

Fulminal myasthenia gravis

Inherited myopathy (e.g. muscular dystrophy)

Ddx for peripheral neuropathies

Ischemic neuromyopathy

Toxoplasmosis/Neospora = polyradiculoneuritis

Toxins (Vincristine, cisplatin, OPs, carbamates)

Diabetes mellitus/insulinoma

Hyperlipidaemia

Coonhound paralysis

Distal denervating disease

Lymphoma

Peripheral nerve sheath tumours

Paraneoplastic syndrome

Breed specific degenerative disorders

Prognosis for diabetic neuropathy

Guarded

Controlling blood sugar prevents progression

Signs of peripheral nerve sheath tumours

Chronic lameness (4-6w) with poor response to analgesia

Severe muscle atrophy +/- neurological deficits +/- self mutilation +/- palpable mass (axial/rectal)

Diagnosis of peripheral nerve sheath tumours

Electromyography - muscle denervation U/S or MRI for mass

Lumbar CSF to exclude neuritis

Treatment of peripheral nerve sheath tumours

Amputation if distal enough

Poor prognosis

Transmission of neospora caninum

Transplacental

Age of presentation of weakness in puppies with neospora caninum

3-8w

Signs of neospora caninum in puppies

Progressive LMN signs in pelvic limbs

Quadriceps contracture

Diagnosis of neospora caninum

Serology/PCR CSF

Biopsy - neuritis/myositis +/- parasites present

Treatment of neospora caninum or toxoplasma gondii

TMPS and clindamycin for >4w

Also treat rest of litter

Transmission of toxoplasma gondii in cats

Transplacental

Oral

Pathogenesis of Coonhound paralysis/polyradiculoneuritis

IM disease of multiple nerve roots = flaccid paralysis

Due to racoon bites, vaccinations, idiopathic (more common with raw diets)

Signs of Coonhound paralysis/polyradiculoneuritis

Flaccid paralysis and hyporeflexia of hindlimbs (progresses to forelimbs) +/- bark affected +/- respiratory problems (if severe)

Treatment of Coonhound paralysis/polyradiculoneuritis

None - usually improves by itself over 2-6w

Physiotherapy helpful

Neuropraxia

Interruption of nerve conduction but no physical axon disruption e.g. blunt trauma, compression Spontaneous recovery in 2-6w

Axonotmesis

Physical disruption of the axon but endoneurium and Schwann cells intact

Long recovery (muscle may have atrophied too far to recover by the time the nerve has recovered)

Neurotomesis

Complete transection of the nerve

Very poor prognosis

Pathogenesis of botulism

Prevention of ACh release = flaccid paralysis

Treatment of botulism in small animals

Supportive care

Recover in 3w

Pathogenesis of tick paralysis

Toxin in saliva of some tick species (not in UK) prevents ACh release = flaccid paralysis

Treatment of tick paralysis

Remove tick = recovery in 1-3d

Ddx for peripheral nervous diseases causing exercise intolerance

Myasthenia gravis

Exercise induced collapse in Labradors

Myopathies (e.g. polymyositis, inherited myopathies)

Congenital form of myasthenia gravis

Rare (seen in Fox Terriers, Jack Russels, Dachshunds); some breeds have a genetic test

Secondary to congenital problem with ACh receptors

Progressive

Pathogenesis of acquired myasthenia gravis

IM disease - antibodies against the nicotinic receptors at the neuromuscular junction

Can be paraneoplastic

2 forms of acquired myasthenia gravis

Focal = only affects one muscle group

Generalised = all muscles = exercise intolerance, collapsing, paresis

Age at presentation of acquired myasthenia gravis

Bimodal = 1-3y or 9-11y

Diagnosis of acquired myasthenia gravis

ACH receptor antibodies

Tensilon test (transient improvement when given edrophonium)

Also need to do thoracic radiographs to check for megaoesophagus/aspiration pneumonia and mediastinal masses

Treatment of myasthenia gravis

Piridostigmine +/- prednisolone (immunosuppressant dose)

Management of megaoesophagus/aspiration pneumonia if present

Prognosis for dogs with myasthenia gravis

About 50% mortality in first few days

Poor prognostic indicators = aspiration pneumonia, thymoma, pharyngeal weakness

If survive, 90% spontaneously get better

Signs of exercise induced collapse in labradors

5-15 min after intense exercise

Ataxia, flaccid paralysis

Normal mentation

Recovery 5-10min later

Diagnosis of exercise induced collapse in labradors

Genetic test