Encephalopathies, Pt. 2

Question 1

What are 3 anomalous/developmental brain disorders?

Answer 1

1. chiari-like malformation
2. congenital hydrocephalus
3. intracranial arachnoid (quadrigeminal) cyst

Question 2

What is chiari-like malformation? What secondary condition does it commonly cause?

Answer 2

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

Question 3

What signalment is most commonly affected by chiari-like malformation?

Answer 3

small breeds, most commonly young adult Cavalier King Charles Spaniel

Question 4

What are the 4 most common manifestations of chiari-like malformation?

Answer 4

1. multifocal CNS dysfunction
2. cervical myelopathy
3. cerebellovestibular dysfunction
4. forebrain dysfunctions, including seizure activity

Question 5

What are some unique manifestations of chiari-like malformation?

Answer 5

due to syringomyelia

• persistent scratching at head, neck, or shoulder region
• scoliosis
• crying out when defecating

Question 6

What is thought to cause the development of syringomyelia?

Answer 6

accumulation of ECF with reduction in fluid pressure that results when a fluid flows through a constricted section (Venturi effect)

Question 7

How is chiari-like malformation diagnosed? What 4 things are seen?

Answer 7

MRI

1. attenuation/obliteration of dorsal subarachnoid space @ cervicomedullary junction
2. rostral displacement of caudal cerebellum by occiput
3. “kinked” appearance of caudal medulla
4. syringomyelia, cerebellar herniation

Question 8

What are some medical therapy options for patients with chiari-like malformation?

Answer 8

• Gabapentin/Pregabalin
• Tramadol
• Omeprazole
• Acetazolamide - decrease ICP
• Furosemide
• NSAIDs
• Prednisone
• acupuncture

Question 9

What is Pregabalin? How does it compare to Gabapentin?

Answer 9

next generation of Gabapentin

more potent effect at the alpha-2-delta subunit of voltage-gated calcium channels

(2-4 mg/kg PO BID)

Question 10

How is chiari-like malformation surgically managed?

Answer 10

foramen magnum decompression - removal of bone from the caudal occiput and C1 dorsal lamina with resection of meninges

Question 11

What is prognosis of foramen magnum decompression for the treatment of chiari-like malformation like?

Answer 11

80% success rate, BUT 25-50% relapse due to excessive scar tissue impinging FMD site

Question 12

Other than FMD, what is another possible option for surgical chiari-like malformation?

Answer 12

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!

Question 13

What is congenital hydrocephalus?

Answer 13

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

Question 14

What signalment is most commonly seen with congenital hydrocephalus? How do these patients present?

Answer 14

young dogs and cats

forebrain dysfunction

Question 15

What dog breeds are most commonly affected by congenital hydrocephalus?

Answer 15

• Chihuahua
• Yorkshire Terrier
• Maltese
• Boston Terrier
• English Bulldog
• Toy/Mini Poodle
• Lhasa Apso
• Poneranian
• Pekingese

Question 16

How is congenital hydrocephalus diagnosed? How are other diseases ruled out?

Answer 16

typical clinical signs and imaging

CSF analysis

Question 17

What are the 2 treatment options for congenital hydrocephalus?

Answer 17

1. prednisone with diuretics - not commonly used, works best for mild cases
2. surgical shunting - last ditch effort, better option with favorable prognosis

Question 18

How is surgical shunting performed for patients with congenital hydrocephalus?

Answer 18

ventriculoperitoneal shunt (VPS) - move CSF from the ventricles into another body cavity, such as the abdominal cavity

• intracranial shunt placed
• tunneled to the abdomen

Question 19

What complications are associated with ventriculoperitoneal shunt placement for congenital hydrocephalus treatment?

Answer 19

• shunt occlusion or dislodgement
• shunt-related infection

Question 20

What are intracranial arachnoid cysts? How are they diagnosed? What medical treatment is performed?

Answer 20

noncancerous fluid-filled sac that grows on the brain or spinal cord

MRI or CT

prednisone with diuretics

Question 21

What is the most commonly suggested surgical treatment for intracranial arachnoid cysts?

Answer 21

fenestration or shunting - cytsoperitoneal shunt with caudolateral craniotomy

• suspected link with caudal occipital malformation syndrome

Question 22

What is hypoglycemic encephalopathy? What are 3 causes?

Answer 22

coma/stupor due to blood glucose levels at 45 mg/dL or less

1. pancreatic insulinoma
2. insulin overdose
3. miniature/toy breed puppies or kittens with increased glucose requirements

Question 23

What is mitochondrial encephalopathy? What signalment is most commonly affected?

Answer 23

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

Question 24

What is seen on MRI in patients with mitochondrial encephalopathy?

Answer 24

bilaterally symmetric lesions

Question 25

What is organic acidurias? What signalment is most commonly affected?

Answer 25

measurable organic acid accumulation due to enzyme deficiencies in respiratory chain enzymes

young dogs

Question 26

What are 2 signs of organic acidurias? How is it diagnosed?

Answer 26

1. multifocal/diffuse CNS dysfunction
2. bilaterally symmetrical MRI lesions

increased levels of organic acids