Spina Bifida Flashcards
Spina -
of the spine
Bifida –
split
Spina Bifida =
type of neural tube defect that occurs when one or more vertebrae fail to fuse at approximately 28 days of gestation, leaving the spinal cord unprotected in utero
Prevalence =
0.4 to 0.9 per 1000 births
Higher prevalence in Hispanics and Caucasians compared to African Americans and Asians
90-95% have no family history of Spina Bifida
Neural Tube Development and Spina Bifida:
By day 18-20 of gestation, the ectoderm (outer embryonic layer) thickens to form the neural plate, which will become the CNS
neural plate folds to form a groove, and the sides (neural folds) rise to close this groove into a tube, the neural tube
process of neural tube closure starts in the middle of the embryo and proceeds both toward the head (cranial end) and tail (caudal end), completing by day 28
Neural Tube Defect Leading to Spina Bifida:
occurs when the caudal end of the neural tube (the part that forms the spinal cord and vertebrae) fails to close properly by day 28
incomplete closure leads to the spinal cord and surrounding structures (bones, skin, etc.) being improperly formed or exposed, resulting in a range of physical and neurological impairments
Open spinal dysraphism (OSD) –
Meninges and/or nerve tissue are exposed to the external environment
due to a lack of skin or membrane covering
Most prevalent
generally more severe forms of neural tube defects
Closed spinal dysraphism (CSD) –
defect in the vertebrae or neural tube is covered by skin, and neural tissue is not exposed
Mildest form of the condition - may still cause significant functional impairments
Open Dysraphism (Open Neural Tube Defects) Examples:
Myelomeningocele
Anencephaly
Encephalocele
Closed Dysraphism (Closed Neural Tube Defects) Examples:
Spina Bifida Occulta
Lipomyelomeningocele
Tethered Cord Syndrome
Prenatal Diagnosis:
13-15 weeks: Blood Lab – Alpha-fetoprotein (AFP), 80% reliable
16-24 weeks: Fetal Ultrasound, >90% reliable
16-18 weeks: Amniocentesis, ~100% accurate
Complexity:
Complications can range from minor to severe physical and mental disabilities
The higher the malformation occurs on the back, the greater the amount of nerve damage and loss of muscle function and sensation
___ most common
L5-S1
Impact determined by:
Size/Location of malformation
Open vs closed
Which spinal nerves are involved
Causes and Risk Factors:
Exact cause is still an unknown
Genetic
Nutritional
Environmental
Folic acid
Genetic Factors:
most cases of spina bifida occur in families with no history of the condition
a family history of neural tube defects slightly increases the risk
genetic mutations or variations may affect the body’s ability to process folic acid
genes involved in the folate metabolism pathway, such as the MTHFR gene, have been linked to an increased risk
Nutritional Factors:
Folic Acid Deficiency
* essential for the proper closure of the neural tube
Women who do not get enough folic acid before and during the first trimester have a significantly higher risk of having a child with spina bifida or other NTDs
Malnutrition or deficiencies in other essential vitamins and minerals
Environmental Factors:
Some medications taken during pregnancy, especially anti-seizure drugs like valproic acid and carbamazepine
diabetes, obesity, and hyperthermia (exposure to high body temperatures, such as from fever or hot tub use during early pregnancy)
environmental toxins, such as alcohol, smoking, or certain chemicals
Older maternal age (above 35)
Folic acid =
(vitamin B9), when taken by the mother prenatally reduces the risk of neural tube defects by up to 70%
plays a key role in DNA synthesis and cell division
FDA/CDC Recommendation –
all women of childbearing age ingest 0.4 mg (400 µg) of folic acid every day
Dietary sources include dark leafy greens, whole grains, and legumes
Neuromuscular, Sensory and Motor Deficits:
Loss of sensation
Loss of muscle strength and control
Loss of bowel/bladder control
Muscle contractures
Skeletal Impairments:
Foot abnormalities (eg, club foot)
Shorter legs
Decreased bone density
Scoliosis
Hip subluxation and dislocation
Other Possible Complications:
Hydrocephalus
Arnold Chiari Malformation
Seizures
Cognitive impairments
Tethered Cord
Bowel/bladder complications
Latex allergy
Hydrocephalus =
Caused by a disturbance of formation, flow or absorption of cerebrospinal fluid
Approximately 25% at birth, which increases up to 90% who will require a ventriculoperitoneal (VP) shunt
Hydrocephalus Signs & Symptoms:
Headaches
Nausea
Lethargy
Vision problems
Hoarse cry
Swallow issues
Changes in speech
Seizures
Arnold-Chiari Malformation Type II:
Portion of the brain stem descends into the cervical spine.
structural abnormalities at the junction of the brain and spinal cord
particularly affecting the cerebellum and brainstem
strongly associated with myelomeningocele
Arnold-Chiari Malformation Type II Signs & Symptoms:
Changes in breathing pattern
Swallowing problems (e.g., gagging)
Ocular muscle palsies
Weakness/spasticity in arms
Bradycardia
Club Foot:
congenital talipes equinovarus
20-50% of infants with spina bifida
causes the foot to be twisted inward and downward, making it appear as if the person is walking on the side or top of their foot
can occur in one or both feet and ranges from mild to severe
Key Features of Clubfoot:
Equinus: The foot points downward, like a ballerina pointing the toes.
Varus: The heel is turned inward.
Cavus: The arch of the foot is elevated.
Forefoot Adduction: The front of the foot (forefoot) is turned inward.
Club Foot Many factors:
Muscle imbalance
Contractures
Intrauterine positioning
Spasticity
Club Foot Muscle imbalance =
flexor muscles (which pull the foot downward) may be stronger or tighter than the extensor muscles (which pull the foot upward),
causing the foot to point down and inward
Club Foot Contractures =
tight tendons and ligaments, particularly the Achilles tendon
can prevent the foot from moving into a normal position
pulling it into equinus (pointed downward) and varus (inward-facing) positions
soft tissues can become less elastic, making it difficult to reposition the foot without interventio
Club Foot Intrauterine Positioning =
Oligohydramnios (reduced amniotic fluid) can limit fetal movement, increasing the risk of musculoskeletal deformities
positional clubfoot occurs when the foot is forced into an abnormal position due to lack of space in utero
*more flexible and easier to correct than idiopathic
Club Foot Spasticity =
increased muscle tone and involuntary muscle contractions
can be more challenging to treat because of the ongoing muscle spasticity and abnormal reflexes, often requiring a combination of orthopedic management and spasticity treatments (e.g., botulinum toxin injections or selective dorsal rhizotomy)
Tethered Cord =
20-50% of children with spina bifida and re-tethering occurs for 10-15%
Caused by the spinal cord becoming fastened to part of the vertebral column which results in the spinal cord becoming abnormally stretched with the child’s growth
Tethered Cord Signs and symptoms:
Weakness
Scoliosis
Pain
Orthopedic deformity
Urologic dysfunction
Change in function
Tethered Cord dimple:
potential external signs
at the base of the spine, typically in the lumbosacral region
small indentation in the skin located at the base of the spine (usually above the buttocks)
Tethered Cord “Y” gluteal cleft:
groove between the buttocks
Y” shape may be visible in the lower part of the gluteal cleft due to abnormal skin changes or other indicators like a dimple, patch of hair, or fatty mass
Motor and Sensory Testing:
motor level is determined by the most caudal segment of the spinal cord that has normal function
motor Level determined by which muscle group can be graded at least 3/5 MMT scale
C5
Elbow Flexors
Biceps, brachialis
C6
Wrist extensors
Extensor carpi radialis longus, extensor carpi radialis brevis
C7
Elbow extensors
Triceps
T1
Small finger abductors
Abductor digiti minimi