Ch16 Primary Spinal Anomalies Flashcards
What is the typical location of a spinal arachnoid cyst?
Almost always dorsal. If ventral then think of neurenteric cyst or arachnoiditis
What are the treatment options for arachnoid cysts?
Drainage, resection, fenestration and shunting (cysto-peritoneal)
What is spina bifida occulta?
Congenital absence of the spinous process +/- other posterior elements with no exposure of the meninges or neural tissue. Incidence = 10%
What is a meningocele?
Herniation of the meninges but not neural diffuse through spinal defect
What is a myelomeningocele?
Herniation of the meninges and neural tissue through a spinal defect
When does the cranial neuropore close?
Day 25
When does the caudal neuropore close?
Day 28
What is the incidence of spina bifida (myelomeningocele)?
1 in 1,000
What lowers the incidence of myelomeningocele?
Folate supplementation
What is the incidence of hydrocephalus with myelomeningocele?
80%. Note closure of the defect converts a latent hydrocephalus to a active one as there is no other route for CSF egress
What allergy is commonly found in patients with myelomeningocele?
Latex allergy in 75%
What does the MOMS study show?
Intrauterine closure of myelomeningocele reduces incidence of hydrocephalus and type 2 chiari.
How do you manage a fetus with spina bifida?
Measure size of defect
If ruptured then start abx
Cover with sterile dressing to prevent dessication
Lie patient on stomach to prevent pressure on MM
Closure within 24 hours
Following surgical closure of a myelomeningocele what are good prognostic signs?
Spontaneous movement of the LLs No chiari 2 (if present check for stridor and apnoeas) No HCP (do head USS)
Why do patients with sacral myelomeningocele get clawing of the feet?
As the foot intrinsics are supplied by S1-3
What other anomalies are associated with myelomeningoceles?
Pulmonary immaturity
Bladder dysfunction (need catheterization)
Scoliosis
Hip and knee deformities
What are the key steps of a myelomeningocele repair?
- Free the placode from the dura to avoid tethering and release the filum terminale
- Re-approximate the placode by suturing the pia
- Water-tight dural closure
- Facia and skin closure
What happens if there are any epithelial remnants on the placode?
Dermoid cysts arise
What is the cause of a CSF leak after a myelomeningocele repair?
Hydrocephalus
What is the most important factor to rule out when a patient with a myelomeningocele deteriorates?
Shunt malfunction
What is the benefit of detethering the cord during myelomeningocele repair?
May improve scoliosis
What is the main cause of mortality in patients with myelomeningocele?
Complications associated with the Chiari 2 malformation - aspiration / respiratory arrest etc and shunt failure
What are the 3 important spinal dysraphisms associated with lipoma?
Intradural lipoma
Lipomyelomeningocele
Lipoma of the filum terminale
These all occur due to early (premature) dysjunction
What is the embryological cause of myelomeningoceles?
Non-dysjunction (which is part of primary neurulation)
What proportion of myelomeningocele patients become ambulatory?
50-80% with bracing
What are the cutaneous stigmata associated with spina bifida?
Fatty pads, port-wine stains, hair tuft, dermal sinus opening or skin appendages
What embyrological process causes a dermal sinus?
Failure of dysjunction
What types of cysts are associated with dermal sinuses?
Epidermoid or Dermoid depending on the contents
What is the difference between an epidermoid and a dermoid?
Epidermoids contain epithelium, Dermoids contain skin and hair.
When should dermal sinuses be excised surgically?
When above the lumbosacral region; Coccyx sinuses do not need to be treated unless infections occur.
What is the management of dermal sinuses?
Surgical exploration and full excision prior to neurological deficit or infection (as they cause recurrent meningitis)
What is Klippel-Feil syndrome?
Congenital fusion of two or more cervical vertebrae
What causes Klippel-Feil syndrome?
Failure of the normal segmentation of cervical somites between weeks 3-8.
What is the clinical triad of Klippel-Feil syndrome?
- Low posterior hair line
- Short neck
- Limited neck movement (affects rotation more)
What is Sprengel’s deformity?
Raised scapula due to failure to descend to normal position (assoc with Klippel-Feil)
What is tethered cord syndrome?
Abnormally low conus (below L2) - assoc with short thickened filum (>2 mm) or intradural lipoma
What are the causes of worsening symptoms with MM?
Shunt faliure! Consider tethered cord if painful and syringomyelia if painless
How do tethered cords present?
May be asymptomatic, pain, foot deformities, scoliosis, leg weakness, urological symptoms and cutaneous stigmata
How can the filum be differentiated from a nerve root?
Tortuous vessel on the surface of the filum and white appearance.
What are the types of spilt cord malformation?
Type 1 - two hemicords, each with its own central canal, pia and dura. Have a bony septum. Treated by untethering the cord after removing any bony septums and reconstituting a single tube.
Type 2 - two hemicords within a single dural tube separated by a fibrous medial septum
What is the Cannon’s classification for congenital nerve root anomalies?
1 - conjoined roots (2 nerve roots within a common dural sheath)
2 - 2 nerve roots exiting through the same foramen
3 - Adjacent nerve roots are separated by an anastomosis
What is Ecchordosis physaliphora?
Notochordal remnant found in 1-2% of autopsies in the retroclival region. Focal gelatinous mass. Indistinguiable from chrodomas.
