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