Download Diseases of Nervous system

Diseases of Nervous system


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
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).

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
Origin of localized epilepsy
The abnormal impulses originate from a specific area
of the cerebral cortex and do not spread.
Origin of generalized epilepsy
The abnormal impulses originate from the cerebral cortex and spread
Etiology
1.
2.
3.
4.
5.
6.
7.
8.
Genetics in some breeds (autosomal
recessive trait ) as German shepherd
and Collie
Infection: distemper, toxoplasma,
Head trauma and neoplasia
inflammatory condition
Idiopathic (unknown cause)
Hypocalcemia, hypoglycemia,
thiamine deficiency
Renal and hepatic dysfunction
Lead intoxication
Clinical signs


Localized motor activity e.g.,
tonic seizures of one leg or facial
twitching
autonomic signs such as pupil
dilatation, salivation or vomiting
Tonic seizure in limbs
Dilated eye pupil - epilepsy
Diagnosis
1.
2.
3.
4.
Detail case history
Clinical signs if appeared
Lab diagnosis:
1. Urinalysis
2. Serum: hypocalcemia or
hypoglycemia
Radiographic: fracture, trauma
or neoplasia.
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.
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

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)
Clinical signs
1.
2.
3.
4.
5.
Rapid eye movement (REM) during
sleep
Excessive daytime sleeping
muscular twitching, variable
vocalization, facial grimacing and
chewing movements.
Flaccid paralysis (cataplexy)
Attacks can be induced in most
affected animals by exercise or
eating
Sudden bouts of deep sleep
Diagnosis



History
Clinical sign
Stimulation test: Give an affected
dog a bone and within seconds it’s
on the floor
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
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
Etiology and pathogenesis

1.
2.
3.
4.
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)
Bacteria causing meningitis
1.
2.
Pasteurella sp (e.g., P. multocida),
Staphylococcus
1.
2.
3.
3.
4.
5.
6.
aureus,
Staphylococcus epidermidis,
Staphylococcus albus,
Actinomyces sp, Nocardia sp,
Escherichia coli,
Streptococcus sp (e.g., S.
pneumoniae)
Klebsiella sp
Other causes
1.
Viral:
1.
2.
2.
canine distemper,
feline infectious peritonitis
Mycotic infection:
1.
2.
3.
histoplasmosis,
cryptococcosis and
blastomycosis.
Clinical signs
1.
2.
3.
4.
5.
hyperesthesia,
fever,
cervical pain, and frequently, cervical
rigidity.
In addition, vomiting, bradycardia,
anorexia, occasional cranial nerve
deficits, and seizures may be observed.
1. Seizures may be caused by high
fever, brain edema, or inflammation,
2. while vomiting may result from
increased intracranial pressure or
from direct effects on the vomiting
center
Stiff gait and walking with caution (as
walking on eggs)
Congested MM (fever in meningitis
Rigidity in the neck
Diagnosis



Case history
Clinical signs
CSF examination for
 color, protein and Gram stain
 Cells (neutrophilia if bacteria is the
cause)
Treatment
1.
2.
3.
4.
Antibacterial: can pass blood-brain barrier
1.
Chloramphenicol (50 mg/kg, IV, IM, or SC,
bid),
2.
metronidazole (10 - 15 mg/kg, PO, tid),
3.
trimethoprim-sulfonamide (30 - 60 mg/kg,
PO, daily
4.
Ampicillin, 5 - 10 mg/kg, IV, every 6 hours
Anticonvulsant (antiseizure): Diazepam
Anti-inflammatory: prednisone 2mg/kg
Osmotic diuretics may be useful for treating
increased intracranial pressure secondary to
brain edema.
ENCEPHALITIS
Definition
 Encephalitis is inflammation of
brain tissue that may extend to
spinal cord (encephalomyelitis)
causing seizures, circling and
blindness in dogs
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
Clinical Signs
1.
2.
3.
4.
5.
6.
7.
8.
9.
Seizures,
Depression,
Abnormal gait and incoordination
Blindness,
Walking in circle
Staring off into space,
Pressing their heads against the
wall or furniture,
Ataxia (a staggering walk), and
Intermittent screaming.
Diagnosis
1.
2.
3.
4.
5.
6.
The disease is hard to diagnose since its
symptoms often relate to other CNS diseases.
Seizures may be caused by many other
underlying conditions such as hypoglycemia,
canine distemper, rabies,
Analyzing the white blood cells in the spinal
fluid
Most often the disease is diagnosed after the
dog die
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
Magnetic Resonance Imaging (MRI) is a
diagnostic test that allows visualization of the
structures of the brain)
Treatment
1.
2.
3.
4.
Anticonvulsants, such as
phenobarbital, may help control
seizures
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
Amphotericin B: 0.1 to 0.5 mg/kg body
weight, IV, three times weekly (for
mycotic encephalitis)
Ivermectin: 0.2 mg/kg S/C
5- FELINE SPONGIFORM
ENCEPHALOPATHY (FSE)
Definition
 Specific brain disease affecting cats
related to bovine spongiform
encephalopathy (BSE) and scrapie in
sheep.
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 scrapieinfected 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 posttranslational modification of a host-encoded
membrane-bound cellular glycoprotein
produced by infection that accumulates in the
affected brain
Clinical signs
1.
2.
3.
4.
5.
6.
7.
8.
9.
Muscle tremors
Ataxia (especially of the pelvic limbs)
Dilated pupils, Jaw
champing,Salivation
Behavioral abnormalities such as
uncharacteristic aggression, biting
Hyperesthesia
Creeping about the house and hiding
Vacant staring
Excessive grooming, and being easily
startled (fear) by noise
Kangaroo-like movements in advanced
cases
Diagnosis
1.
2.
3.
History
Clinical signs
Microscopic exam: diffuse
vacuolation (single or multiple
vacuoles) of gray matter and neurons
throughout the brain, particularly in
cerebral cortex
Treatment


There is no treatment.
Prognosis is poor, since all spongiform
encephalopathy cases are fatal.
Questions