Diseases of Nervous system

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Diseases of Nervous system
Epilepsy

• Definition
• A condition characterized by recurrent seizures
  (two or more) result from an abnormal and
  excessive neuronal discharge. epileptic seizures
  are a sign of cerebral dysfunction

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Characteristics

• Three main characteristics of epileptic seizures
  are
• the loss of control (in various degrees),
• the episodic nature of the attacks (they start
  suddenly and they terminate suddenly), and
• the repetitive clinical pattern (attacks are
  identical from episode to episode).

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Types

• Localized caused by localized area of brain
  dysfunction (the epileptic focus in cerebral
  cortex and do not spread) and symptoms are
  related to area involved.
• Generalized The abnormal impulses originate from
  the cerebral cortex and spread

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Origin of localized epilepsy
The abnormal impulses originate from a specific
area of the cerebral cortex and do not spread.
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Origin of generalized epilepsy
The abnormal impulses originate from the cerebral
cortex and spread
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Etiology

1. Genetics in some breeds (autosomal recessive
   trait ) as German shepherd and Collie
2. Infection distemper, toxoplasma,
3. Head trauma and neoplasia
4. inflammatory condition
5. Idiopathic (unknown cause)
6. Hypocalcemia, hypoglycemia, thiamine deficiency
7. Renal and hepatic dysfunction
8. Lead intoxication

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Clinical signs

• Localized motor activity e.g., tonic seizures of
  one leg or facial twitching
• autonomic signs such as pupil dilatation,
  salivation or vomiting

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Tonic seizure in limbs
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Dilated eye pupil - epilepsy
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Diagnosis

1. Detail case history
2. Clinical signs if appeared
3. Lab diagnosis
4. Urinalysis
5. Serum hypocalcemia or hypoglycemia
6. Radiographic fracture, trauma or neoplasia.

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Treatment

• Treatment of primary cause
• Antiepileptic Drugs
• Phenobarbital 3 - 5 mg/kg/day (one daily dosage
  or divided and administered twice a day)
• potassium bromide/sodium bromide 20 - 40 (60)
  mg/kg /day (one daily dosage)
• Primidone  20-30mg/kg/day
• Phenytoin 2.0 - 5.0 mg/kg given as a slow IV
  injection.

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Narcolepsy
Definition

• Narcolepsy is a neurological disorder associated
  with abnormalities of rapid eye movement sleep
  with excessive daytime sleepiness
• Occurs sporadically in dogs and rarely, in cats
• cataplexy is often the dominant clinical sign,
  which is characterized by sudden paroxysmal
  attacks of flaccid paralysis (muscle atony) with
  conservation of consciousness, that may last from
  a few seconds to more than 20 minutes

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Etiology

• Imbalance between cholinergic (e.g., hyperactive)
  and catecholaminergic (e.g., hypoactive)
  neurotransmitter systems within the CNS due to
• diffuse encephalitis
• Canine distemper
• Genetic predisposition (recessive trait)

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Clinical signs

1. Rapid eye movement (REM) during sleep
2. Excessive daytime sleeping
3. muscular twitching, variable vocalization, facial
   grimacing and chewing movements.
4. Flaccid paralysis (cataplexy)
5. Attacks can be induced in most affected animals
   by exercise or eating

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Sudden bouts of deep sleep
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Diagnosis

• History
• Clinical sign
• Stimulation test Give an affected dog a bone and
  within seconds its on the floor

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Treatment

• intravenous imipramine at a dose of 0.5 mg/kg.
• imipramine is an antidepressant act to change the
  balance of naturally occurring chemicals in the
  brain (neurotransmitters) that regulate the
  transmission of nerve impulses between cells
• Atropine sulfate 0.1 mg/kg, IV

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Meningitis

• Definition
• Inflammation of meninges of brain (pia, dura and
  arachnoid) that may involve brain
  (meningioencephalitis) or brain and spinal cord
  (meningioencephalomyelitis), characterized
  clinically by hyperesthesia and rigidity of the
  neck
• most affected dogs are adult, with a mean age
  around 5 years

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Etiology and pathogenesis

• Bacterial infections of the CNS most often occur
  via
• hematogenous spread from distant foci within the
  body (e.g., lung or splenic abscess, vegetative
  endocarditis, pleuritis, and urinary tract
  infections),
• by direct extension from sinuses, ears and eyes,
  as a result of trauma,
• meningeal spread with entry along nerve roots, or
  
• from contaminated surgical instruments (e.g.,
  spinal needle)

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Bacteria causing meningitis

1. Pasteurella sp (e.g., P. multocida),
2. Staphylococcus
3. aureus,
4. Staphylococcus epidermidis,
5. Staphylococcus albus,
6. Actinomyces sp, Nocardia sp,
7. Escherichia coli,
8. Streptococcus sp (e.g., S. pneumoniae)
9. Klebsiella sp

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Other causes

1. Viral
2. canine distemper,
3. feline infectious peritonitis
4. Mycotic infection
5. histoplasmosis,
6. cryptococcosis and
7. blastomycosis.

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Clinical signs

1. hyperesthesia,
2. fever,
3. cervical pain, and frequently, cervical rigidity.
   
4. In addition, vomiting, bradycardia, anorexia,
   occasional cranial nerve deficits, and seizures
   may be observed.
5. Seizures may be caused by high fever, brain
   edema, or inflammation,
6. while vomiting may result from increased
   intracranial pressure or from direct effects on
   the vomiting center
7. Stiff gait and walking with caution (as walking
   on eggs)

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Congested MM (fever in meningitis
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Rigidity in the neck
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Diagnosis

• Case history
• Clinical signs
• CSF examination for
• color, protein and Gram stain
• Cells (neutrophilia if bacteria is the cause)

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Treatment

1. Antibacterial can pass blood-brain barrier
2. Chloramphenicol (50 mg/kg, IV, IM, or SC, bid),
3. metronidazole (10 - 15 mg/kg, PO, tid),
4. trimethoprim-sulfonamide (30 - 60 mg/kg, PO,
   daily
5. Ampicillin, 5 - 10 mg/kg, IV, every 6 hours
6. Anticonvulsant (antiseizure) Diazepam
7. Anti-inflammatory prednisone 2mg/kg
8. Osmotic diuretics may be useful for treating
   increased intracranial pressure secondary to
   brain edema.

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ENCEPHALITIS

• Definition
• Encephalitis is inflammation of brain tissue that
  may extend to spinal cord (encephalomyelitis)
  causing seizures, circling and blindness in dogs

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Etiology

• A-Viral
• 1. Canine distemper,
• 2. Rabies (rhabdovirus)
• 3. Herpes virus (puppies)
• B- Granulomatous encephalitis (mycotic, e.g.
  Cryptococcus and Histoplasma).
• C-Parasitic
• 4. Dirofilaria immitis or
• 5. Canine Angiostrongylus vasorum infestation
• 6. Toxoplasmosis (toxoplasma gondi)
• D- Genetic condition

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Clinical Signs

1. Seizures,
2. Depression,
3. Abnormal gait and incoordination
4. Blindness,
5. Walking in circle
6. Staring off into space,
7. Pressing their heads against the wall or
   furniture,
8. Ataxia (a staggering walk), and
9. Intermittent screaming.

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Diagnosis

1. The disease is hard to diagnose since its
   symptoms often relate to other CNS diseases.
2. Seizures may be caused by many other underlying
   conditions such as hypoglycemia, canine
   distemper, rabies,
3. Analyzing the white blood cells in the spinal
   fluid
4. Most often the disease is diagnosed after the dog
   die
5. Positive diagnosis may be made through use of
   immunofluorescent or immunocytochemical
   techniques to detect canine distemper viral
   antigen in brain sections and other tissues
   (e.g., mononuclear cells in blood smears,
   conjunctival or tracheal washes
6. Magnetic Resonance Imaging (MRI) is a diagnostic
   test that allows visualization of the structures
   of the brain)

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Treatment

1. Anticonvulsants, such as phenobarbital, may help
   control seizures
2. Anti-inflammatory oral prednisone, 1 to 2
   mg/kg/day initially for several days, then
   reducing the dosage to 2.5 - 5 mg on alternate
   days
3. Amphotericin B 0.1 to 0.5 mg/kg body weight, IV,
   three times weekly (for mycotic encephalitis)
4. Ivermectin 0.2 mg/kg S/C

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5- FELINE SPONGIFORM ENCEPHALOPATHY (FSE)

• Definition
• Specific brain disease affecting cats related to
  bovine spongiform encephalopathy (BSE) and
  scrapie in sheep.

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Etiology and pathogenesis

• Oral exposure from consumption of foodstuffs
  derived from cattle contaminated with the BSE
  agent which in turn was spread to cattle through
  animal protein concentrates (e.g., meat and
  bone-meal) processed from scrapie-infected sheep
  carcasses.
• The infectious agent in these spongiform
  encephalopathies is a protease resistant prion
  protein (PrP), a product of nerve cells, and
  considered to be an abnormal post-translational
  modification of a host-encoded membrane-bound
  cellular glycoprotein produced by infection that
  accumulates in the affected brain

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Clinical signs

1. Muscle tremors
2. Ataxia (especially of the pelvic limbs)
3. Dilated pupils, Jaw champing,Salivation
4. Behavioral abnormalities such as uncharacteristic
   aggression, biting
5. Hyperesthesia
6. Creeping about the house and hiding
7. Vacant staring
8. Excessive grooming, and being easily startled
   (fear) by noise
9. Kangaroo-like movements in advanced cases

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Diagnosis

1. History
2. Clinical signs
3. Microscopic exam diffuse vacuolation (single or
   multiple vacuoles) of gray matter and neurons
   throughout the brain, particularly in cerebral
   cortex

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Treatment

• There is no treatment.
• Prognosis is poor, since all spongiform
  encephalopathy cases are fatal.

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• Questions