Encephalopathies, Pt. 2 Flashcards
What are 3 anomalous/developmental brain disorders?
- chiari-like malformation
- congenital hydrocephalus
- intracranial arachnoid (quadrigeminal) cyst
What is chiari-like malformation? What secondary condition does it commonly cause?
congenital malformation of the skull resulting in overcrowding of caudal fossa and compression of the cervicomedullary junction
cervical syringomyelia - fluid-filled cyst (syrinx) forms within the spinal cord
What signalment is most commonly affected by chiari-like malformation?
small breeds, most commonly young adult Cavalier King Charles Spaniel
What are the 4 most common manifestations of chiari-like malformation?
- multifocal CNS dysfunction
- cervical myelopathy
- cerebellovestibular dysfunction
- forebrain dysfunctions, including seizure activity
What are some unique manifestations of chiari-like malformation?
due to syringomyelia
- persistent scratching at head, neck, or shoulder region
- scoliosis
- crying out when defecating
What is thought to cause the development of syringomyelia?
accumulation of ECF with reduction in fluid pressure that results when a fluid flows through a constricted section (Venturi effect)
How is chiari-like malformation diagnosed? What 4 things are seen?
MRI
- attenuation/obliteration of dorsal subarachnoid space @ cervicomedullary junction
- rostral displacement of caudal cerebellum by occiput
- “kinked” appearance of caudal medulla
- syringomyelia, cerebellar herniation
What are some medical therapy options for patients with chiari-like malformation?
- Gabapentin/Pregabalin
- Tramadol
- Omeprazole
- Acetazolamide - decrease ICP
- Furosemide
- NSAIDs
- Prednisone
- acupuncture
What is Pregabalin? How does it compare to Gabapentin?
next generation of Gabapentin
more potent effect at the alpha-2-delta subunit of voltage-gated calcium channels
(2-4 mg/kg PO BID)
How is chiari-like malformation surgically managed?
foramen magnum decompression - removal of bone from the caudal occiput and C1 dorsal lamina with resection of meninges
What is prognosis of foramen magnum decompression for the treatment of chiari-like malformation like?
80% success rate, BUT 25-50% relapse due to excessive scar tissue impinging FMD site
Other than FMD, what is another possible option for surgical chiari-like malformation?
cranioplasty with the goal of decreasing the rate of post-op scar tissue
- standard FMD + titanium screws around the periphery of the occipital defect and the placement of a titanium mesh and polymethylmethacrylate plate
- fewer re-operations!
What is congenital hydrocephalus?
excessive CSF accumulation thought to be caused by obstructions and inadequate absorption or abnormal compliance of the brain due to a brain/cranial cavity mismatch
What signalment is most commonly seen with congenital hydrocephalus? How do these patients present?
young dogs and cats
forebrain dysfunction
What dog breeds are most commonly affected by congenital hydrocephalus?
- Chihuahua
- Yorkshire Terrier
- Maltese
- Boston Terrier
- English Bulldog
- Toy/Mini Poodle
- Lhasa Apso
- Poneranian
- Pekingese
How is congenital hydrocephalus diagnosed? How are other diseases ruled out?
typical clinical signs and imaging
CSF analysis
What are the 2 treatment options for congenital hydrocephalus?
- prednisone with diuretics - not commonly used, works best for mild cases
- surgical shunting - last ditch effort, better option with favorable prognosis
How is surgical shunting performed for patients with congenital hydrocephalus?
ventriculoperitoneal shunt (VPS) - move CSF from the ventricles into another body cavity, such as the abdominal cavity
- intracranial shunt placed
- tunneled to the abdomen
What complications are associated with ventriculoperitoneal shunt placement for congenital hydrocephalus treatment?
- shunt occlusion or dislodgement
- shunt-related infection
What are intracranial arachnoid cysts? How are they diagnosed? What medical treatment is performed?
noncancerous fluid-filled sac that grows on the brain or spinal cord
MRI or CT
prednisone with diuretics
What is the most commonly suggested surgical treatment for intracranial arachnoid cysts?
fenestration or shunting - cytsoperitoneal shunt with caudolateral craniotomy
- suspected link with caudal occipital malformation syndrome
What is hypoglycemic encephalopathy? What are 3 causes?
coma/stupor due to blood glucose levels at 45 mg/dL or less
- pancreatic insulinoma
- insulin overdose
- miniature/toy breed puppies or kittens with increased glucose requirements
What is mitochondrial encephalopathy? What signalment is most commonly affected?
heritable deficiencies in mitochondrial enzymes resulting in diffuse, symmetric encephalo(myelo)pathy due to a buildup of lactate and pyruvate in the brain
young dogs
What is seen on MRI in patients with mitochondrial encephalopathy?
bilaterally symmetric lesions
What is organic acidurias? What signalment is most commonly affected?
measurable organic acid accumulation due to enzyme deficiencies in respiratory chain enzymes
young dogs
What are 2 signs of organic acidurias? How is it diagnosed?
- multifocal/diffuse CNS dysfunction
- bilaterally symmetrical MRI lesions
increased levels of organic acids
