current strategies for management of intervertebral disc...
TRANSCRIPT
Current Strategies for Management of Intervertebral Disc Disease.
Ashley Bensfield, DVM, DACVIM (Neurology)
Objectives
• Pathophysiology/terminology• Where the confusion about IVDD comes from• Diagnostics• Treatment options• Prognosis
Pathophysiology/Terminology
• Type of Intervertebral Disc Disease Hansen Type I Hansen Type II Hansen Type III
• Myelopathy –spinal cord dysfunction• Spinal Hyperesthesia – misused, but accepted abnormal pain on spinal palpation. Synonym - hyperpathia
IVDD
Hoerlein 447
Pathophysiology/Terminology
• Upper motor neuron deficits – spastic, normo-to hyperreflexive
• Lower motor neuron deficits – Decreased tone, normo- to hyporeflexive.
• Nociception – conscious perception of painful stimulus
• Withdrawal Reflex– Reflexive flexion of limb with noxious stimulus to toe
Spinal Reflex Arc
Platt 21
Pathophysiology/Terminology
• Superficial pain perception Conscious response to mildly noxious stimulus
• Light pinch, needle prick
• Deep pain perception Conscious response to bone crushing pain.
• Paresis – inability to move body part with appropriate strength
Pathophysiology/Terminology
• Plegia – paralysis – inability to move body part• Ataxia – impaired coordination of movement Proprioceptive Vestibular Cerebellar
• Proprioception – knowledge of where body parts are in space w/o having to look at them.
Why is IVDD so confusing?
• Impossible to find all the information in one place
• Numerous persistent incorrect anecdotal practices - e.g.: Surgery not needed unless paralyzed Medical management should be tried/failed
before surgery considered IVDD is not a systemic disease Length of medical management time is arbitrary
References – This is a partial list!• Brisson, B et al. “Comparison of the effect of single-site and multiple-site disk fenestration on the rate of recurrence of the thoracolumbar
intervertebral disk herniation in dogs.” J Am Vet Med Assoc 2001; 238: 1583-1600.• Brisson, B et al. “Recurrence of thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs after surgical decompression with or without
prophylactic fenestration: 265 cases (1995-1999).” J Am Vet Med Assoc 2004; 224: 1808-1814.• De Risio, L et al. “Association of clinical and magnetic resonance imaging findings with outcome in dogs with presumptive acute noncompressive
nucleus pulposus extrusion: 42 cases (2000-2007).” J am Vet Med Assoc 2009:234:495-504.• Flegel, T et al. “Partial Lateral Corpectomy of the Thoracolumbar Spine in 51 Dogs: Assessment of Slot Morphometery and Spinal Cord
Decompression.” Veterinary Surgery, 40 (2011) 14-21.• Forterre, F et al. “Microfenestration Using the CUSA Excel Ultrasonic Aspiration System in Chondrodystrophic Dogs with Thoracolumbar Disk
Extrusion: A Descriptive Cadaveric and Clinical Study.” Veterinary Surgery, 40 (2011) 34-39.• Gomes, SA, et al. “Clinical and magnetic resonance imaging characteristics of thracolumbar intervertebral disk extrusions and protrusions in large
breed dogs.” Vet Radiol Ultrasound, Vol. 00, No. 0, 2016, pp 1-10.• Hecht, S. et al. “Myelography vs. computed tomography in the evaluation of acute thoracolumbar intervertebral disk extrusion in chondrodystrophic
dogs.” Veterinary Radiology & Ultrasound, Vol. 50, No. 4, 2009, pp 353-359.• Hoerlein, BF. Canine Neurology: Diagnosis and Treatment, 3rd Ed. W. B. Saunders Company. Philadelphia. 1978• Israel, SK et al. “Relative sensitivity of computed tomograpny and myelography for identification of thoracolumbar intervertebral disk herniations in
dogs.” Veterinary Radiology & Ultrasound, Vol. 50, No. 3, 2009, pp 247-252.• Jeffrey, N et al. “Factors associated with recovery from paraplegia in dogs with loss of pain perception in the pelvic limbs following intervertebral disk
herniation.” J Am Vet Med Assoc 2016;248:386-394.• Jensen, VF, et al. “Quantification of the association between intervertebral disk calcification and disk herniation in Dachshunds.” J Am Vet Med Assoc
2008; 233:1090-1095.• Levine, JM, et al. “Magnetic Resonance Imaging in Dogs with Neurological Impairment Due to acute Thoracic and Lumbar Intervertebral Disk
Herniation.” J Vet Intern Med. 2009; 23: 1220-1226.• McKee, WM, et al. “Presumptive exercise-associated peracute thoracolumbar disc extrusion in 48 dogs.” Veterinary Record (2010)166, 523-528.• Olby, NJ, et al. “Prevalence of Urinary Tract Infection in Dogs after Surgery for Thoracolumbar Intervertebral Disc Extrusion.” J Vet Intern Med
2010;24: 1106-1111. • Platt, S and N Olby. BSAVA Manual of Canine and Feline Neurology, 4th Ed. BSAVA. Glouchester. 2013• Sharp, NJH and Simon Wheeler. Small Animal Spinal Disorders: Diagnosis and Surgery, 2nd Ed. Elsevier Mosby. Philadelphia. 2005• Taylor-Brown, FE, and Steven De Decker. “Presumptive acute non-compressive nucleus pulposus extrusion in 11 cats: clinical features, diagnostic
imaging findings, treatment and outcome.” Journal of Feline Medicine and Surgery. 2017, Vol 19 (1) 21-26.
Hansen Type I IVDD
• Herniation, rupture, extrusion of nucleus pulposus through a tear in the annulus pulposus Abnormal/unhealthy nucleus pulposus material,
unable to withstand normal forces Mineralized nucleus pulposus
• chondroid degeneration
Hansen Type I IVDD
• Pain and paresis/plegia caused by: compression of spinal cord and nerve roots Bruising type injury to spinal cord Pain from stretching/tearing of disc annulus and
dorsal longitudinal ligament
Hansen Type III IVDD
• Catch all phrase• Rupture of IVDD capsule under pressure
(traumatic) with explosive extrusion of nucleus pulposus.
• Synonyms: High Velocity Low Volume Extrusion, Missile Disc,
Acute Non-compressive Nucleus Pulposus Extrusion (ANNPE), Splatter disc (overlaps with Type I), Liquid Disc
Type I and III IVDD Signalment
• Peracute to gradual (days) onset• Spinal hyperesthesia• Abnormal posturing• Muscle spasms• Paresis/paralysis• +/- abnormal reflexes• +/- decreased or absent nociception
Type I and III IVDD Signalment
• Young (4-6y) chondrodystrophic dog breeds, and middle aged (6-8) non-chondrodystrophic. In young dachshunds – association btwn number
of mineralized discs on radiographs and risk for future Type I IVDD
• Young to middle aged cats• Type III associated with exercise/activity Similar presentation to FCE and/or spinal trauma
Neurolocalization• UMN signs generally carry a better prognosis than LMN
signs. LMN signs - dysfunction of spinal cord intumescence
(neuron cell bodies for the LMNs reside). • Damage to cell body results in permanent loss of that neuron.
UMN signs – axon damage/dysfunction. • Spinal cord/nerve axons have much greater ability to
regenerate/resist injury.• Hyperesthesia – if present, site of pain usually indicates
location of IVDD.• Cutaneous Trunci reflex – 1-2 segments caudal to site
of injury
Schiff-Sherrington Posture
• Acute thoracolumbar junction spinal cord injury Loss of upper motor neuron inhibition to
forelimbs Increased extensor tone in forelimbs• Forelimb proprioception, voluntary motor and reflexes
normal to increased
Mistaken for Opisthotonos• SSP – no central vestibular or RAAS signs.
Does not give information about prognosis.
Platt 6
Nerve Root Signature
Sharp 93
Myelomalacia
• “Spinal cord” – “Softening” Ischemic death of the spinal cord Can be focal, but often progresses to the “ascending-
descending” form. Fatal due to progression cranially to the areas of the
spinal cord controlling respiratory muscles• Occurs in 10% of patients with acute paraplegia
and loss of nociception May not manifest for up to 7-10 days (usually under 5) No treatment, including surgery, shown to prevent.
Myelomalacia
• Clinical signs Ascending cutaneous trunci reflex cutoff
• This reflex should not decrease further after 24hrs post-op or post-disc extrusion.
• Track daily by marking patient’s back with permanent marker
Flaccid abdomen and pelvic limbs Patient appears restless/uncomfortable May be hyper- or hypothermic Progressive respiratory paralysis
Sharp 128
Hansen Type II IVDD
• Thickening and protrusion of annulus fibrosus• Fibrous metaplasia of nucleus pulposus• May be associated with spondylosis
deformans (ankylosing).• Paresis caused by compression of spinal cord
and/or nerve roots. May result in spinal cord gliosis and nerve atrophy
• Pain caused by nerve root compression
Type II IVDD Signalment
• Older, generally large breed dogs or older cats• Chronic slowly progressive paresis +/- spinal
pain Often reluctant to jump or use stairs “getting old,” “slowing down.”
• Can acutely worsen• +/- nerve root signature or paresthesia
Differential Diagnoses
• Other causes of pain and/or myelopathy FCE, spinal fracture, discospondylitis, neoplasia,
myelitis (infectious/auto-immune), Deg. Myel., COMS.• Other causes of LMN weakness Neuropathy, myopathy, junctionopathy (MG),
electrolyte disturbances, diabetes mellitus, plexus avulsion.
• General causes of weakness Hypotension, hypoglycemia, hemoabdomen, etc.
• Orthopedic disease/joint pain Bilateral CCL disease, hip dysplasia, polyarthropathy
Diagnostics – Physical Exam
• General PE Back pain and abdominal pain can be hard to
differentiate Particular attention to causes of weakness
• Thorough auscultation, palpate pulses, ballotteabdomen, check MM color.
Thorough orthopedic exam
Diagnostics-Neurological Examination
• Importance of performing neuro exam on normal patients. Make sure patient adequately supported to differentiate
weakness from CP deficit.• Should be mentally appropriate• Cranial nerves – Possible Horner’s Syndrome if
cervical/high thoracic. Otherwise normal.• Nociception-if limbs move voluntarily, pain sensation
should be present – no need to aggressively test. Reflex does not equal nociception!
• Remember tail/perineum!
Diagnostics- Neurological Examination
• Spinal palpation, neck range of motion If suspect animal is painful, do this step last! Neck pain and partial seizures can look similar Neck pain dogs will hunch their T/L spine too.
• Voluntary Motor assessment• Assess patients in quiet room On the floor Good footing
Olby Fig.7-2, 3rd Ed
Diagnostics – Minimum Database
• Complete blood count (with manual diff)• Chemistry profile (with CPK)• Urinalysis (with sediment)• +/- Tick testing• Aspergillus antigen German Shepherds• DM genetic test – Boxers, GSD, Corgi • +/- Neoplasia screening if over 8yrs (3-view
CXR/AUS)• Viral testing for cats. • ECG/BP if renal dz, arrhythmia, poor pulses, etc.
Diagnostics - Imaging
• Radiographs Low yield for IVDD Provides information about
• Congenital malformations• Spinal fracture• Osteolytic disease – cancer, osteomyelitis,
discospondylitis, etc.
V/D views less helpful, especially if not sedated COLLIMATE – not a time for cat/dog-o-gram
Diagnostics - Myelography• Technically challenging but inexpensive.• General anesthesia, iodinated compound injected into
epidural space. Causes reactive meningitis x 2 weeks and small area of
permanent focal damage to lumbar spinal cord where needle penetrates.
May cause seizures• Highlights extradural compression Does not always provide accurate side/site Does not give information about health of spinal cord. Helpful in evaluating Type II IVDD for dynamic compression Does not differentiate neoplasia, etc. from IVDD.
Diagnostics – CT +/- myelography• Rapidly identify acute, compressive, Type I, thoracolumbar
IVDD in young dogs. Site, side, extent
• Not as helpful for differentiating acute/chronic sites.• Does not provide information about health of spinal cord.• More expensive than myelography, less expensive than MRI• Helpful in evaluating Type II lesions for dynamic
compression with myelography.• Does not always differentiate IVDD from neoplasia, etc. IV contrast administration can help.
Hansen Type I IVDD
Hansen Type I IVDD
Diagnostics - MRI
• Best modality for evaluating IVD, spinal cord, and nerve roots Not as good bone detail as CT. Evaluates spinal cord for edema/gliosis.
• More prognostic information than CT or myelography More readily differentiates acute vs. chronic sites. Can evaluate dynamic compression
• More time consuming and expensive than myelography or CT.
Hansen Type I IVDD
Hansen Type II IVDD
Treatment options – Medical
• Type I Rest, anti-inflammatory medication, pain
management, bladder management• 6 weeks cage rest, no jumping/stairs for life• NSAID OR anti-inflammatory dose of steroids
– 10-14 days only.
• Manage secondary damage – hydration, free radicals, etc.• +/- muscle relaxer, opioid, and/or gabapentin• +/- bladder management
– U-cath, intermittent catheterization, manual expression.– Prazosin (1mg/15kg TID) +/- diazepam, +/- bethanechol
Treatment Options - Medical
• Type II Physical therapy and/or intermittent cage rest. Long term vs. pulse anti-inflammatory
medications Long term gabapentin and/or tramadol. No jumping or stairs +/- bladder management
Treatment Options - Surgical
• Hemilaminectomy• Dorsal Laminectomy• Lateral Corpectomy• Ventral Slot• Distraction/fusion• Fenestration – Reduces risk of future Type I
Treatment – Post-OP
• 2-4 weeks strict rest, no jumping/stairs for life• Gradual return to walking, then running, and
playing.• Anti-inflammatory therapy x 10-14 days• Tramadol, gabapentin as needed• Muscle relaxer – diazepam, methocarbamol,
5-7 days
Treatment Options - Complementary
• Acupuncture• Laser Therapy – for muscle soreness.• Physical therapy – when? How much?• Massage• Ice/Hot packing
Prognosis Type I or III, acuteNeuro-localization
Pain + Medical Pain + Sx Pain - Medical Pain - Sx
C1-C5 50 %, 30-50% Relapse
90-95% N/A N/A
C6-T2 50%, 30-50% Relapse
70-95% N/A N/A
T3-L3 70%, 30% Relapse
90-95% 10% 50-55%, Timing???
L4-S1 50-70%, ~50% relapse
70-90% Less than 10% 10-30%, Timing???
**with pain +, no change in prognosis for surgical success ~8wks from time of injury. However, if become pain -, prognosis decreases as above.**
Prognosis Type I, chronic, pain +
• Because of additional scar tissue, prognosis with surgery decreased by about 20-25% if surgery performed >8wks after herniation
Prognosis Type II• Degree of spinal cord atrophy difficult to quantify. No improvement in neurological grade with surgery if due
to atrophy Decreased functional reserve
• More likely to be worse following surgery– Minor trauma during surgery = “last straw effect”
• Surgical vs. conservative management have similar outcomes Indications to try surgery
• Chronic pain• Paralysis• Improved neurological grade with anti-inflammatories.• Owner goals – try to prevent further worsening knowing risk
References• Brisson, B et al. “Comparison of the effect of single-site and multiple-site disk fenestration on the rate of recurrence of the thoracolumbar
intervertebral disk herniation in dogs.” J Am Vet Med Assoc 2001; 238: 1583-1600.• Brisson, B et al. “Recurrence of thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs after surgical decompression with or without
prophylactic fenestration: 265 cases (1995-1999).” J Am Vet Med Assoc 2004; 224: 1808-1814.• De Risio, L et al. “Association of clinical and magnetic resonance imaging findings with outcome in dogs with presumptive acute noncompressive
nucleus pulposus extrusion: 42 cases (2000-2007).” J am Vet Med Assoc 2009:234:495-504.• Flegel, T et al. “Partial Lateral Corpectomy of the Thoracolumbar Spine in 51 Dogs: Assessment of Slot Morphometery and Spinal Cord
Decompression.” Veterinary Surgery, 40 (2011) 14-21.• Forterre, F et al. “Microfenestration Using the CUSA Excel Ultrasonic Aspiration System in Chondrodystrophic Dogs with Thoracolumbar Disk
Extrusion: A Descriptive Cadaveric and Clinical Study.” Veterinary Surgery, 40 (2011) 34-39.• Gomes, SA, et al. “Clinical and magnetic resonance imaging characteristics of thracolumbar intervertebral disk extrusions and protrusions in large
breed dogs.” Vet Radiol Ultrasound, Vol. 00, No. 0, 2016, pp 1-10.• Hecht, S. et al. “Myelography vs. computed tomography in the evaluation of acute thoracolumbar intervertebral disk extrusion in chondrodystrophic
dogs.” Veterinary Radiology & Ultrasound, Vol. 50, No. 4, 2009, pp 353-359.• Hoerlein, BF. Canine Neurology: Diagnosis and Treatment, 3rd Ed. W. B. Saunders Company. Philadelphia. 1978• Israel, SK et al. “Relative sensitivity of computed tomograpny and myelography for identification of thoracolumbar intervertebral disk herniations in
dogs.” Veterinary Radiology & Ultrasound, Vol. 50, No. 3, 2009, pp 247-252.• Jeffrey, N et al. “Factors associated with recovery from paraplegia in dogs with loss of pain perception in the pelvic limbs following intervertebral disk
herniation.” J Am Vet Med Assoc 2016;248:386-394.• Jensen, VF, et al. “Quantification of the association between intervertebral disk calcification and disk herniation in Dachshunds.” J Am Vet Med Assoc
2008; 233:1090-1095.• Levine, JM, et al. “Magnetic Resonance Imaging in Dogs with Neurological Impairment Due to acute Thoracic and Lumbar Intervertebral Disk
Herniation.” J Vet Intern Med. 2009; 23: 1220-1226.• McKee, WM, et al. “Presumptive exercise-associated peracute thoracolumbar disc extrusion in 48 dogs.” Veterinary Record (2010)166, 523-528.• Olby, NJ, et al. “Prevalence of Urinary Tract Infection in Dogs after Surgery for Thoracolumbar Intervertebral Disc Extrusion.” J Vet Intern Med
2010;24: 1106-1111. • Platt, S and N Olby. BSAVA Manual of Canine and Feline Neurology, 4th Ed. BSAVA. Glouchester. 2013• Sharp, NJH and Simon Wheeler. Small Animal Spinal Disorders: Diagnosis and Surgery, 2nd Ed. Elsevier Mosby. Philadelphia. 2005• Taylor-Brown, FE, and Steven De Decker. “Presumptive acute non-compressive nucleus pulposus extrusion in 11 cats: clinical features, diagnostic
imaging findings, treatment and outcome.” Journal of Feline Medicine and Surgery. 2017, Vol 19 (1) 21-26.
