Cerebrospinal Fluid, Lumbar Puncture and Hydrocephalus Flashcards
what is CSF?
Cerebrospinal fluid (CSF) surrounds the brain and spinal cord, and may function as a shock absorber for the CNS. It may also serve an immunological function analogous to the lymphatic system. It circulates within the subarachnoid space, between the arachnoid and the pial membranes. CSF is normally a clear colorless fluid with a specific gravity of 1.007 and a pH of ≈ 7.33–7.35.
what are the two main functional subdivisions of subnormal CSF reabsorption?
obstructive hydrocephalus (AKA non-communicating)
communicating hydrocephalus (AKA non-obstructive)
CSF overproduction: rare.As with some choroid plexus papillomas; even here, reabsorption is probably defective in some as normal individuals could probably tolerate the slightly elevated CSF production rate of these tumors.
what is obstructive hydrocephalus?
block proximal to arachnoid granu- lations (AG) On CTor MRI: enlargement of ventricles proximal to block (e.g. obstruction of aqueduct of Sylvius →lateral and 3rd ventricular enlargement out of proportion to the 4th ventricle, sometimes referred to as triventricular hydrocephalus)
what is communicating communicating hydrocephalus (AKA non-obstructive)?
defect in CSF reabsorption by the AG
why is CSF overproduction rare?
As with some choroid plexus papillomas; even here, reabsorption is probably defective in some as normal individuals could probably tolerate the slightly elevated CSF production rate of these tumors.
what are congenital abnormalities that cause defects in CSF absorption?
Chiari Type 2 malformation and/or myelomeningocele (MM) (usually occur together)
Primary aqueductal stenosis (usually presents in infancy, rarely in adulthood)
DandyWalker malformation: atresia of foramina of Luschka & Magendie
what are aquired abnormalities that cause defects in CSF absorption?
infectious (the most common cause of communicating HCP)
post-hemorrhagic (2nd most common cause of communicating HCP) (premature baby
secondary to masses
what is chiari II malformation?
type 1 Chiari malformation symptoms and signs can show up in infants, children, teens or adults.
Type 2 Chiari malformation is associated with spina bifida and is present at birth.
what is aquaduct stenosis?
The cerebral aqueduct, also referred to as the aqueduct of Sylvius, is a channel that carries cerebrospinal fluid (CSF) from the third to the fourth ventricle. Aqueductal stenosis means that this channel becomes narrow and does not allow CSF to properly flow through. This can lead to the accumulation of CSF in the brain, a condition known as hydrocephalus. As much CSF accumulates, it leads to brain compression and associated symptoms such as headache, vomiting, nausea, changes in mental status, and seizures. Children with hydrocephalus can present with head enlargement, intellectual disability, and developmental delay. The diagnosis is typically made with a CT scan or MRI.
what is dandy walker malformation?
In severe cases, DWM can lead to problems with the flow of a fluid in the brain called cerebrospinal fluid (CSF). A buildup of CSF in the brain leads to a condition called hydrocephalus. Children with a buildup of CSF may have macrocephaly, a very large head.
DWM is congenital. This means it is something a child is born with, not something that appears later in childhood. DWM can be diagnosed during pregnancy. There is no cure for DWM, but supportive care is available.
what is a posterior fossa tumour?
Posterior fossa tumors are more common in children than in adults
Hydrocephalus is common in children with posterior fossa tumors, occurring in 71-90% of pediatric patients; approximately 10-40% demonstrate persistent hydrocephalus after posterior fossa tumor resection. [9, 10, 11, 12]
Hydrocephalus associated with posterior fossa tumors affects the quality of life of patients. Routine preoperative cerebrospinal fluid diversion is not necessary for most patients with posterior fossa tumor–related hydrocephalus
what are symptoms of abnormal CSF reabsorption?
In older children (with rigid cranial vault) and adults
Symptoms are those of increased ICP, including: papilledema, H/A, N/V, gait changes, upgaze and/or abducens palsy. Slowly enlarging ventricles may initially be asymptomatic.
In young children
● abnormalities in head circumference (OFC) ● cranium enlarges at a rate >facial growth ● irritability, poor head control, N/V ● fontanelle full and bulging ● enlargement and engorgement of scalp veins ● “setting sun sign” (upward gaze palsy) ● 6th nerve (abducens) palsy ● irregular respirations with apneic spells ● splaying of cranial sutures
what investigations are done for abnormal CSF reabsorption?
MRI, CT, U/S
how is abnormal CSF reabsorption treated?
Lumbar puncture
Lumbar drain
External Ventricular Drain
Endoscopic Third Ventriculostomy
Ventriculo-Peritoneal Shunt
what is an external ventricular drain?
External ventricular drainage (EVD) is a temporary method of draining cerebrospinal fluid (CSF) from the ventricles in the brain
The drainage system works by using gravity. This means the amount of CSF that can drain away depends on the position of the drip chamber or cylinder beneath the ventricles.
The drain will be inserted in an operation under general anaesthetic, lasting between one and two hours. The surgeon will feed the drainage tube under your child’s skin to the exit site
