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| − | ==Nerve Injury==
| + | {{toplink |
| − | ===Classification of Peripheral Nerve Disease=== | + | |backcolour = E0EEEE |
| − | {| cellpadding="4" cellspacing="0" border="2"
| + | |linkpage = Nervous System - Pathology |
| − | |-
| + | |linktext =Nervous System |
| − | |style="background:#B0E0E6; color:black" width="200"|'''By Nerve Type | + | |maplink = Nervous System (Content Map) - Pathology |
| − | |style="background:#B0E0E6; color:black" width="200"|'''By Anatomy''' | + | |pagetype =Pathology |
| − | |style="background:#B0E0E6; color:black" width="250"|'''By Pathology''' | + | }} |
| − | |-
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| − | |
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| − | *Mixed
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| − | |
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| − | *NMJ
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| − | |'''Neuronopathy :''' ''The Whole nerve cell''
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| − | |-
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| − | |
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| − | *Motor
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| − | |
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| − | *Distal / Proximal
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| − | |'''Axonopathy :''' ''The axon''
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| − | |-
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| − | |
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| − | *Sensory
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| − | |
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| − | *Root / Spinal Cord
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| − | |'''Demyelination:''' ''Schwann cell''
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| − | |-
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| − | |}
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| | <br> | | <br> |
| − |
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| − | ===Types of Injury===
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| − | {| cellpadding="4" cellspacing="0" border="2"
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| − | |-
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| − | |style="background:#B0E0E6; color:black"|'''Neuropraxia:'''||
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| − | *Temporary interruption of conduction - no histological change.
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| − | |-
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| − | |style="background:#B0E0E6; color:black"|'''Axonotmesis:'''||
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| − | *Axon interupted but basal lamina intact (e.g. crush injury)
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| − | *Regeneration occurs along original path - prospect for functional recovery good.
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| − | |-
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| − | |style="background:#B0E0E6; color:black"|'''Neurotmesis:'''||
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| − | *Axon '''and''' basal lamina interupted (e.g. transection injury)
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| − | *Success of regeneration depends on finding the correct distal stump
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| − | |}
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| − | <br>
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| − |
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| − | ===Clinical Signs with Peripheral Nerve Disease===
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| − | {| align="center" cellpadding="4" cellspacing="0" border="0"
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| − | |width="350"|
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| − | :<u>'''Motor Neuropathy Signs (LMN signs)'''</u>
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| − | |width="350"|
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| − | :<u>'''Sensory Neuropathy'''</u>
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| − | |width="350"|
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| − | :<u>'''Autonomic Neuropathy'''</u>
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| − | |-
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| − | |
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| − | *Flaccid paresis/paralysis of innervated structures
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| − | |
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| − | *Decreased or abherrant 'pain' response or sensation
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| − | *Anisocoria (dilated / constricted pupils)
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| − | |-
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| − | *Neurogenic muscle atrophy (very rapid)
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| − | |
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| − | *Proprioceptive defects
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| − | *Decreased tear production
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| − | |-
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| − | |
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| − | *Reduced / absent reflexes and muscle tone
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| − | |
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| − | *Abnormal sensation (paraesthesia)/sensitivity (dysthesia)
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| − | |
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| − | *Decreased salivation
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| − | |-
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| − | |
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| − | *Reduced / absent reflexes without muscle atrophy
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| − | |
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| − | *Bradycardia
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| − | |}
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| − | <br>
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| − |
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| − | ==Peripheral Nerve Disease in Small Animals==
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| − | {| cellpadding="4" cellspacing="0" border="2"
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| − | |- style="background:#B0E0E6; color:black"
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| − | |width="150"|<center><big>'''Disease'''</big></center>
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| − | |width="200"|<center><big>'''Pathology'''</big></center>
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| − | |width="250"|<center><big>'''Clinical Signs'''</big></center>
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| − | |width="250"|<center><big>'''Diagnosis'''</big></center>
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| − | |width="250"|<center><big>'''Prognosis + Treatment'''</big></center>
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| − | |-
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| − | |<center><big>'''[[Distal Denervating Disease]]'''</big></center>
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| − | |
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| − | *Distal axonopathy, possibly of toxic origin
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| − | |
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| − | *Tetraparesis
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| − | *Dysphonia / Aphonia
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| − | *Neck Weakness
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| − | *Tetraparesis developing to tetraplegia in severe cases ''floppy dog''
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| − | *Sensory function preserved: Pain but '''no''' withdrawal
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| − | |
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| − | *Biopsy / EMG unhelpful
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| − | |
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| − | *Very good prognosis
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| − | *Recovery in 3-6 weeks by '''axon regeneration'''
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| − | *Good nursing to prevent pressure sores in the recumbant animal
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| − | |- style="background:#F0F8FF; color:black"
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| − | |<center><big><span id="IPRN">'''[[Idiopathic Polyradiculoneuritis]]'''</span></big></center>
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| − | |
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| − | *Immune mediated demyelination often involving roots, directed against unknown epitopes in peripheral myelin.
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| − | *May be post infection
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| − | *May get axonal injury if severe
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| − | |
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| − | *As for distal denervating (although more rapid onset)
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| − | *May have sensory involvement.
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| − | |
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| − | *By clinical signs
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| − | *CSF changes if roots involved
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| − | *Slower nerve conduction
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| − | *H reflexes and F-waves may be lost
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| − | |
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| − | *Very good prognosis
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| − | *Recovery in 3-6 weeks by '''remyelination'''
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| − | *Immunosuppresive levels of corticosteroids (although may delay remyelination)
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| − | |-
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| − | |<center><big>'''[[Polyneuritis Equi|Cauda Equina Traction]]'''</big></center>
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| − | |
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| − | *Tail pull injury
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| − | *Esp. cats after RTA
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| − | *Lesion via longitudinal traction
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| − | *Sacrocaudal dislocation/fracture
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| − | |
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| − | *Limp tail
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| − | *Incontinence
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| − | *Hindlimb Paresis
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| − | |
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| − | *Diagnosis on Clinical signs and history
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| − | *+/- Radiographs to show dislocation/fracture
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| − | |
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| − | *Prognosis difficult to predict
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| − | *Poor prognosis if tail limp & no anal tone
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| − | *Supportive treatment
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| − | *'''Persist for >3 months if possible'''
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| − | |- style="background:#F0F8FF; color:black"
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| − | |<center><big>'''[[Peripheral Nerve Tumours]]'''</big></center>
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| − | |
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| − | *Nerve sheath tumours
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| − | *Generally tumours of Schwann cells
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| − | *Common in dog Brachial plexus
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| − | |
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| − | *Chronic single forelimb lameness
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| − | *Weakness
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| − | *Muscle Atrophy
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| − | *Pain in Axilla
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| − | *LMN signs (may get UMN if grows into spinal cord
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| − | |
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| − | *Clinical signs
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| − | *Imaging
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| − | |
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| − | *Prognosis dependant on location
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| − | *Poor prognosis if in spinal cord
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| − | *Amputation of limb?
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| − | |-
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| − | |<center><big>'''[[Key-Gaskell Syndrome|Feline Dysautonomia]]'''</big></center>
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| − | |
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| − | *Common in 1980's - Sporadic now
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| − | *Degeneration (toxic?) of autonomic ganglia
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| − | |
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| − | *Mainly Parasympathetic
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| − | *Vomiting
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| − | *3rd Eyelid protrusion
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| − | *Dilated pupils + poor PLR
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| − | *Reduced Lacrimation
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| − | *Megaoesophagus
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| − | *Bradycardia
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| − | |
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| − | *Clinical signs
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| − | *Poor Prognosis
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| − | *Supportive therapy only
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| − | *Similar sporadic disease seen in dogs
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| − | |-
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| − | |}
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| − |
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| − | ==Peripheral Nerve Disease in Large Animals==
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| − | {| cellpadding="4" cellspacing="0" border="2"
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| − | |-- style="background:#B0E0E6; color:black"
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| − | |width="150"|<center><big>'''Disease'''</big></center>
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| − | |width="200"|<center><big>'''Pathology'''</big></center>
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| − | |width="250"|<center><big>'''Clinical Signs'''</big></center>
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| − | |width="250"|<center><big>'''Diagnosis'''</big></center>
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| − | |width="250"|<center><big>'''Prognosis + Treatment'''</big></center>
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| − | |-
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| − | |<center><big>'''[[Laryngeal Hemiplegia|Idiopathic Laryngeal Hemiplagia (ILH)]]'''</big></center>
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| − | |
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| − | *Progressive loss of fibres (esp. large diameter) within left recurrent laryngeal nerve compared to right
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| − | *[[Peripheral Nervous System - Response to Injury#The 'Dying Back' Phenomenon|Dying back]] axonopathy with myelin sheath involvement:
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| − | **Degenerating fibres
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| − | **Regenerating clusters
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| − | **De/Re-myelination
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| − | *Flattening of nerve between aorta & trachea
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| − | |
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| − | *Inspiratory 'roaring' noise - flapping of vocal fold
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| − | |
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| − | *'Slap test' - adduction of contralateral arytenoid during expiration
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| − | *Endoscopic examination - assymetric arytenoids, poor abduction of left vocal fold.
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| − | *Palpable atrophy of laryngeal musculature
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| − | |
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| − | *Laryngeal Ventriculectomy (Hobday procedure)
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| − | *'Tie Back'
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| − | *Laryngeal muscle prosthesis
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| − | *Prognosis usually good
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| − | |-style="background:#F0F8FF; color:black"
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| − | |<center><big>'''[[Polyneuritis Equi|Cauda Equina Neuritis]]'''</big></center>
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| − | |
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| − | *Equine version of [[#IPRN|Idiopathic polyradiculoneuritis]]
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| − | *Extradural nerve roots of cauda equina thickened and discoloured
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| − | *Inflammatory infiltrate (lymphocytes, plasma cells, macrophages)
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| − | *Extensive axonal damage and demyelination
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| − | *Cranial nerve involvement often occurs
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| − | *Aetiology unknown:
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| − | **Antecedent infection?
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| − | **Antibodies to PNS myelin?
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| − | |
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| − | *Paralysis & anaesthesia of tail
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| − | *Urinary incontinence
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| − | *Loss of anal reflex
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| − | *Failure to defaecate
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| − | *Pain/hypersensitivity in gluteal/tail-head area
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| − | |
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| − | *Clinical signs
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| − | *Recovery unlikely - most animals are destroyed.
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| − | |-
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| − | |<center><big>'''[[Stringhalt]]'''</big></center>
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| − | |
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| − | *Causes poorly understood - similar signs caused by sweat pea plant ingestion (lathyrism)
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| − | *Distal axonopathy (esp. large diameter fibres)
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| − | |
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| − | *Abrupt onset continuous / intermittent hyperflexion of one or both hind limbs
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| − | *May also have ataxia, urinary incontinence, perineal flaccidity
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| − | |
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| − | *Differential diagnosis : Upward fixation of patella
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| − | |
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| − | *May get spontaneous recovery
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| − | *Move pasture
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| − | *Tenectomy of lateral digital extensor may help
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| − | |-
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| − | |-style="background:#F0F8FF; color:black"
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| − | |<center><big>'''[[Equine Motor Neuron Disease]]'''</big></center>
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| − | |
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| − | *Generalised LMN disorder
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| − | *Degeneration of Ventral horn motor neuron
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| − | *[[Peripheral Nervous System - Response to Injury#Chromatolysis|Chromatolysis]]
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| − | *Neurofilament accumulation
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| − | *Gliosis
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| − | *[[Wallerian Degeneration|Wallerian degeneration]]
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| − | *Denervation changes in muscle
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| − | |
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| − | *Weight Loss
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| − | *Muscle atrophy
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| − | *Generalised Weakness
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| − | *Short strided gait + narrow based stance
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| − | *Trembling
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| − | *Sweating and fasiculations
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| − | *Increased recumbency
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| − | |
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| − | *Elevated CK
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| − | *CSF protein
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| − | *Denervation of EMG
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| − | |
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| − | *May progress to constant recumbency (destroy), stabilise or improve
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| − | |-
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| − | |<center><big>'''[[Suprascapular Nerve Injury]]'''</big></center>
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| − | |
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| − | *'''"Sweeney"'''
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| − | *Commonly damaged by horse colliding into objects
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| − | *Fibrous entrapment as nerve reflected around wing of scapula
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| − | *Atrophy of supra- and infra- spinatous muscles
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| − | |
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| − | *Lateral luxation of shoulder when weight bearing
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| − | *Muscle wasting around shoulder
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| − | |
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| − | *Clinical signs
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| − | *History
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| − | |
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| − | *No more than 30cm regrowth in 12 months expected due to irreversible muscle fibrosis.
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| − |
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| − | |-
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| − | |}
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| − |
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| − | ==Other Polyneuropathies==
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| − | *Tick Paralysis
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| − | *Vincristine Toxicity
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| − | *Endocrine polyneuropathy
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| − | **Dogs - hypothyroidism, insulinoma, diabetes mellitus
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| − | **Cats - diabetes mellitus
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| − | *Genetic polyneuropathies
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| − | *Protozoan polyradiculoneuritis
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| − | *Idiopathic facial paralysis (e.g. Bell's Palsy)
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| − | *Botulism
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| − |
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| − | [[Category:Peripheral Nervous System - Pathology|A]]
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