The Nervous System

1. The Nervous System And its associated diseases

2. Diseases of Brain: Trauma Dog skull and brain 2º Trauma: edema, hemorrhage 1º Trauma—Direct trauma to (↑ intracranial pressure) brain tissue

3. Brain: Trauma • Signs: • Seizures • Blood in eyes, ears, nose, oral cavity • Loss of consciousness or decrease in response to external stimuli • Shock, coma, altered respiratory patterns • Dx • Hx of trauma (HBC, falling) • Chem. panel to rule out other metabolic diseases

4. Brain: Trauma • Treatment—aimed at reducing 2° effects (edema) • Osmotic agents: Mannitol (20-50%) IV slow bolus • Diuretics: Furosemide IV q4h • Anti-seizure Rx if needed: Diazepam, Phenobarbital • Client info • Some brain injury is irreversible • Dog in coma >48 h usually does not survive • Worsening neuro signs → bad prognosis

5. Idiopathic Vestibular Disease Signalment: Dogs (middle aged) and cats, acute • Signs • Loss of balance • Head tilt • Nystagmus • Disorientation • Ataxia • Vomiting/anorexia

6. Idiopathic Vestibular disease http://www.youtube.com/watch?v=ZccUdSH91zc&feature=PlayList&p=E13C63C661759E7C&playnext_from=PL&playnext=3&index=30 http://www.youtube.com/watch?v=Y25T7dZ77T4&feature=related

7. Idiopathic Vestibular Disease • Dx • Clinical signs • Blood work to r/o other diseases of nervous system • Ear exam to r/o inner ear infection • Rx • Treatment is not recommended; does not alter course of disease (antibiotics, steroids often given to cover possible causes not found by PE and lab work) • Clinical signs resolve in 3-6 wks

8. Brain: Neoplasia • Enlarging mass in brain; causes compression of healthy tissue or replacement with cancerous tissue • Signs (usually progressive) • Depends on tumor location • Seizures increasing in frequency and intensity • Vestibular signs (depending on location) • Tremors, ataxia

9. Brain: Neoplasia • Dx • Systematic screening for tumors in other organs • CBC, chem panel • Radiographs • CSF tap to assess increased cerebral spinal pressure • Ophthalmic exam may indicate optic nerve edema • Computed tomography (CT) scanning or magnetic resonance imaging (MRI) to locate tumor

10. Brain: Neoplasia • Rx— • Surgical removal of superficial single lesions • Radiation therapy • Chemotherapy; efficacy varies with tumor type (lymphomas respond well; other less so) • Anti-seizure medication (Phenobarbital PO 2-3 times/day) • Corticosteroids—prednisone • Client info • Unless tumor is surgically removed, medications will not cure disease • Symptoms will worsen as tumor grows larger

11. Epilepsy Click for video • Signs of seizure • short aura (stare into distance, seek comfort/protection from someone, vocalize) • seizure lasts 1-2 min; may consist of total body muscle twitching with extended arms and legs and arching of neck dorsally (opisthotonus) • dog will be disoriented/blind for a few minutes • may be a single event (no veterinary intervention needed) or followed shortly by other seizures (status epilepticus- requires veterinary intervention) • may be incited by certain events • normal at other times

12. http://www.thepetcenter.com/gen/epilepsy.html

13. Epilepsy • Dx • CBC, chem panel—r/o metabolic diseases causing seizures • hypoglycemia • hypocalcemia • hepatic encephalopathy (failure to detox blood) • Shunt • Cirrhosis • Pb poisoning • Radiographs—r/o head trauma or hydrocephalus • CT scan or MRI—r/o space-occupying lesion in brain • Rx—directed at cause if one can be found • treat if >1 every mo or two (Rx will not completely stop seizures) • Phenobarbital is TOC

14. Status Epilepticus • Signs—prolonged, uninterrupted seizures • Rx • Diazepam (2-10 mg to effect); can be repeated over several minutes • Phenobarbital - • Time to steady state blood levels: 10-14 days • Side effects: sedation, ataxia, PU/PD/PP, hepatotoxicity, blood dyscrasias (Rare) • Establish an open airway • IV cath with IV fluids to keep an open vein • Monitor blood Ca and glucose; treat is needed • Monitor body temp; if elevated, treat appropriately • If cerebral edema is suspected, treat with mannitol (IV) • Phenobarbital—IV or IM

15. Epilepsy • Client info— • Epilepsy is an incurable disease • Even with treatment, animal may still seize; • goal is to reduce frequency and intensity of seizures • Spaying/neutering will remove any hormonal influence on seizures • Medications will probably be required for life • Most animals that seize can live a normal life • If seizure free for 6-9 mo, may reduced or discontinued Rx

16. Spinal Cord • Function • Nerve fibers carry signals between brain and rest of body • Anatomy • Like brain, protected by hard covering, the vertebral canal

17. Spinal Cord: Anatomy Like brain, spinal cord enclosed in hard covering IVDD problem in both humans and canine Anatomical differences—cervical same; lumbar—human bears weight, canine doesn’t Attached rib (thorax) helps stabilize the IV joint; worse at T-L junction (dogs)

18. Degenerative Disc Disease: Humans Degeneration of disk occurs with age Dries out, shrinks (we get shorter as we age)

19. IV Disk Disease: Anatomy Normal spinal column and disk Prolapsed disk 1/3 thickness nucleus fibrosus

20. Intervertebral Disk Disease • Etiology • IVD dries out with age → hardened, less compliant • ↑Pressure from jumping • Occurs most commonly in cervical, caudal thoracic, and lumbar vertebrae

21. Intervertebral Disk Disease • Hansen TYPE I: Nucleus pulposus herniates upward; narrowest part of annulus fibrosus • TYPE I: Most common in chondrodystrophic (“faulty development of cartilage”) breeds • Dachshunds, shih tzus, Lhasa apsos, beagles, basset hounds (poodles also affected) • Acute onset • Can occur at any age, but generally younger dogs

22. Intervertebral Disk disease • Hansen TYPE 2: dorsal protrusion of the annulus into the spinal canal • Common in older dogs and nonchondrodystrophic breeds • Occurs over a longer period of time • Clinical signs may be less severe • Generally older dogs

23. Intervertebral Disk Disease • Signs: • Pain • Paresis/paralysis; nerve function is lost in this order: • Proprioception—largest fibers; most susceptible to pressure; signs are ataxia • Motor fibers—next smallest fibers; signs are weakness/paresis • Cutaneous sensory fibers—small; require a lot of pressure to disrupt function; decreased panniculus reflex • Deep pain fibers—smallest fibers; require the most pressure to disrupt; loss is associated with poor prognosis

24. Intervertebral Disk Disease • Severity of clinical signs depends on: • Speed at which disk material is deposited • Degree of compression • Duration of compression

25. IVDD – Paralysis of rear legs

26. Cervical IVDD

27. Loss of Deep Pain

28. IVDD Dx: Spine X-Rays Normal horse’s head consistent IV space Subluxation L2-3 (old lesion)

29. IV Disk Disease: Myelogram Which disk space?

30. IV Disk Disease: Myelogram Which disk space?

31. Cervical IVDD Myelogram: Disk herniation at C2-3 (narrowed IV space, narrowed spinal canal)

32. IVDD • Rx TYPE I, acute onset • Medical Rx is recommended for animals, with deep pain intact, with or w/o neuro deficit • High levels of corticosteroids is CONTROVERSIAL • Strict confinement—2 wk minimum (easy when dog hurts; not so easy after steroids/other pain medications take effect) • Nursing care • Soft padded cage • Urinary cath or express bladder several times/day • Surgery is recommended for • repeat offenders • No voluntary motor function • loss of deep pain (needs to be done QUICKLY!) • worsening neuro signs (poor Prognosis)

33. Laminectomy

34. IVDD: Possible sequela

35. IVDD

36. IVDD - rehabilitation http://www.youtube.com/watch?v=7AkNVDc4lig&feature=related

37. IVDD – Alternative/Optional Treatment • Methocarbamol 15-20 mg/kg q 8hr • High-dose Methylprednisolone sodium succinate (CONTROVERSIAL!) and should be given within 8 hours • Although there is proven benefit in humans, results have not been proven in dogs • Low dose prednisone – various regimens • NSAIDS • Carprofen, deracoxib, etodolac • Gastroprotectants • Acupuncture

38. Veterinary Acupuncture • http://www.youtube.com/watch?v=Z-JjZPnk_Mw&feature=related • http://www.youtube.com/watch?v=vJIJDUQyOmw&feature=fvw

39. IVDD • Client info • Do not let susceptible breeds get overweight • Encourage animals to keep spine parallel to ground • No jumping on/off couch • No begging on hind legs • No stair climbing • Loss of deep pain >24 h has poor prognosis • If surgery is done soon enough, there is a good Px of recovery • Almost half of animals treated medically will have recurrence • Extensive home care is required for medical and surgical patients • Severe damage to spinal cord is not reparable