And its associated diseases

The Nervous System

Diseases of Brain: Trauma

Dog skull and brain2º Trauma: edema, hemorrhage

1º Trauma—Direct trauma to (↑ intracranial pressure) brain tissue

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

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

Idiopathic Vestibular Disease• Signs– Loss of balance– Head tilt– Nystagmus– Disorientation– Ataxia– Vomiting/anorexia

Signalment: Dogs (middle aged) and cats, acute

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

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

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

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

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

Epilepsy• 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

Click for video

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

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

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

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

Spinal Cord

• Function– Nerve fibers carry signals between brain and rest of

body

• Anatomy– Like brain, protected by hard covering, the vertebral

canal

Spinal Cord: Anatomy

Like brain, spinal cord enclosed in hard coveringIVDD problem in both humans and canineAnatomical differences—cervical same; lumbar—human bears weight, canine doesn’tAttached rib (thorax) helps stabilize the IV joint; worse at T-L junction (dogs)

Degenerative Disc Disease: Humans

Degeneration of disk occurs with ageDries out, shrinks (we get shorter as we age)

IV Disk Disease: AnatomyNormal spinal column and disk Prolapsed disk

nucleus fibrosus

1/3 thickness

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

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

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

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

Intervertebral Disk Disease

• Severity of clinical signs depends on:• Speed at which disk material is deposited• Degree of compression• Duration of compression

IVDD – Paralysis of rear legs

Cervical IVDD

Loss of Deep Pain

IVDD Dx: Spine X-Rays

Normal horse’s head consistent IV space

Subluxation L2-3(old lesion)

IV Disk Disease: Myelogram

Which disk space?

IV Disk Disease: Myelogram

Which disk space?

Cervical IVDD

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

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)

Laminectomy

IVDD: Possible sequela

IVDD

IVDD - rehabilitation

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

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

Veterinary Acupuncture

• http://www.youtube.com/watch?v=Z-JjZPnk_Mw&feature=related

• http://www.youtube.com/watch?v=vJIJDUQyOmw&feature=fvw

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