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Narcolepsy 676.e1

Video
Narcolepsy Available
VetBooks.ir Diseases and Disorders

BASIC INFORMATION
DIAGNOSIS
• Alpha-2 antagonist
○ Yohimbine 0.15-0.30 mg/kg PO q 12h
Definition Diagnostic Overview • Serotonin/epinephrine reuptake inhibitor
• Alteration in the sleep-wake cycle charac- It is diagnosed by clinical history and observa- ○ Venlafaxine 2.5 mg/kg/day PO
terized by excessive daytime sleepiness and tion, including witnessing an attack of sleep and Treatments to target excessive sleepiness:
cataplexy after a stimulus cataplexy in response to a stimulus. Episodes • Central nervous system (CNS) stimulants
• Cataplexy is the acute, brief loss of muscle can often be elicited by feeding. ○ Dextroamphetamine 5-10 mg PO q 8-12h
tone (flaccid tone) often secondary to a ○ Modafinil 15-60 mg/kg PO q 24h
positive emotional stimulus. Differential Diagnosis (morning)
• Due to the episodic nature of this disease, • Monoamine oxidase B inhibitor
Epidemiology it must be differentiated from ○ Selegiline 1 mg/kg PO q 24h
SPECIES, AGE, SEX ○ Seizures
Age: ○ Syncope Nutrition/Diet
• Familial form: onset 4 weeks to 6 months ○ Sleep-associated movement disorders Feeding bowls should not be made of glass.
of age (REM sleep disorders) Water and food bowls should be kept on an
• Acquired form: 7 months to 7 years of age; ○ Episodic neuromuscular diseases such as elevated surface that is above the shoulder level
mean age of onset of 2-4 years myasthenia gravis of the dog.
• Both forms can be seen in dogs and cats of
either sex. Initial Database PROGNOSIS & OUTCOME
• Neurologic exam: normal
GENETICS, BREED PREDISPOSITION • CBC, biochemistry panel: unremarkable Fair-to-good; there is no cure for narcolepsy or
• Familial form: autosomal recessive mutation • Assessment of videos of the episodes (see cataplexy, but the disease is not life-threatening
in the hypocretin receptor 2 gene; occurs Videos). nor progressive in nature, and episodes can
most commonly in Doberman pinschers, often be minimized with treatment.
Labrador retrievers, and dachshunds. Com- Advanced or Confirmatory Testing
plete penetrance is seen in the Doberman • Food-elicited cataplexy test (FECT): 12 pieces PEARLS & CONSIDERATIONS
and Labrador. of dog food are lined up at set intervals on the
• Acquired (sporadic) form: secondary to a floor; record time it takes for dog to eat all the Comments
decrease in production of hypocretin peptides food, and monitor for episodes during test. Neither intrathecal nor intravenous hypocretin
by the hypothalamus. More than 17 different ○ Normal dog consumes all food in approxi- injections have resulted in clinical improvement
breeds of dogs have been affected. mately 10 seconds. in dogs or humans.
○ Narcoleptic dog likely takes longer to
Clinical Presentation consume all the food and may exhibit Technician Tips
DISEASE FORMS/SUBTYPES one or more attacks. Technicians should understand how clinical
Familial (congenital) and acquired forms of • Physostigmine challenge test: useful for dogs signs of narcolepsy and cataplexy differ from
the disease exist. with milder form of narcolepsy; monitor seizures and syncope.
frequency of episodes after IV administration
HISTORY, CHIEF COMPLAINT of physostigmine 0.05 mg/kg; increased Client Education
• Most common complaint is transient loss frequency of episodes over 5-30 minutes seen Feed and water affected patients on an elevated
of muscle tone that often occurs second- for affected dogs. No episodes are observed surface.
ary to an emotional stimulus (e.g., eating, for normal dogs.
playing); episodes can last seconds to ○ Side effects of physostigmine (an acetyl- SUGGESTED READING
minutes. cholinesterase inhibitor) include salivation, Tonokura M, et al: Review of pathophysiology and
• Increased sleeping, shorter sleep latency, lacrimation, and diarrhea. clinical management of narcolepsy in dogs. Vet
and higher frequency of onset of rapid eye • Measure hypocretin-1 levels in CSF: normal Rec 161:375-380, 2007.
movement (REM) sleep periods are also of 250-350 pg/mL for dogs with familial
described. narcolepsy; levels decreased to < 80 pg/mL ADDITIONAL SUGGESTED
for dogs with acquired narcolepsy READINGS
PHYSICAL EXAM FINDINGS Delucchi L, et al: Use of venlafaxine in the treatment
Physical and neurologic exam findings are TREATMENT of canine narcolepsy-cataplexy case. J Small Anim
normal between episodes. Pract 51:132, 2010.
Treatment Overview Thomas WB, et al: Seizures and narcolepsy. In Dewey
Etiology and Pathophysiology Most treatment is aimed at reducing cataplexy CW, et al, editors: Practical guide to canine and
• Familial form: mutation in the hypocretin episodes. Owners consider cataplexy to have feline neurology, ed 3, Ames, IA, 2016, John Wiley
2 receptor; circulating hypocretin levels in a more pronounced effect on quality of life & Sons, pp 262-263.
brain tissue and cerebrospinal fluid (CSF) compared with excessive sleepiness. AUTHOR: Stephanie A. Thomovsky, DVM, MS,
are normal. DACVIM, CCRP
• Acquired form: secondary to a deficiency Acute General Treatment EDITOR: Karen R. Muñana, DVM, MS, DACVIM
in hypocretin levels in brain tissue and Treatments to target cataplexy:
CSF • Tricyclic antidepressant
• Hypocretin is a neuropeptide produced by ○ Imipramine 0.4-1.0 mg/kg PO q 8-12h
the hypothalamus that plays an important ○ Clomipramine 3.0-6.0 mg/kg PO q 24h
role in the control of sleep and arousal. ○ Fluoxetine 1 mg/kg PO q 24h

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