Hydrocephalus
Hydrocephalus: Excerpt from The 5-Minute Pediatric Consult
Jennifer A. Markowitz, MD
Hydrocephalus - BASICS
Hydrocephalus - description
- Accumulation of CSF in the ventricles and subarachnoid spaces, leading to their enlargement
- Overall head size may enlarge in response, depending on age and cause.
Hydrocephalus - pathophysiology
- Normal pathway of CSF: Choroid plexus and interstitial fluid (sources), lateral ventricles, foramina of Monro, 3rd ventricle, aqueduct of Sylvius, 4th ventricle, foramina of Luschka and Magendie, subarachnoid space, arachnoid villi, and venous circulation
- Hydrocephalus results from obstruction to CSF flow, impaired reabsorption, or overproduction of CSF.
- Noncommunicating (obstructive) hydrocephalus results from obstruction within the ventricular system.
- Communicating hydrocephalus usually results from impaired CSF reabsorption or (rarely) overproduction (e.g., due to a choroid plexus papilloma).
- The noncommunicating/communicating distinction has no prognostic significance, but has implications for etiology and choice of therapeutic intervention.
Hydrocephalus - etiology
- Intraventricular hemorrhage is most commonly due to prematurity, but may also occur with trauma. It results in impaired CSF absorption due to meningeal adhesions, granular ependymitis, and clots. Posthemorrhagic hydrocephalus (PHH) occurs in 35% of all neonates surviving intraventricular hemorrhage; its incidence increases with increasing severity of hemorrhage.
- Tumors or cysts near the foramina or the aqueduct, or within the ventricular system
- Infection (meningitis, intrauterine infection) can lead to leptomeningeal adhesions and granulations which block reabsorption of CSF.
- Developmental:
- Chiari malformation, type II (associated with myelomeningocele, brain migrational disorders, small posterior fossa, inferior displacement of medulla and cerebellar vermis, kinking of the brainstem, aqueductal stenosis, beaking of the tectum)
- Dandy-Walker malformation (absence of cerebellar vermis, small cerebellar hemispheres, enlarged posterior fossa, often with cystic 4th ventricle)
- X-linked and autosomal dominant hydrocephalus; the former is often associated with aqueductal stenosis and mutations in L1CAM on Xq28.
- Sporadic primary aqueductal stenosis
- Dysmorphic syndromes (e.g., Apert syndrome, Cockayne syndrome, Crouzon syndrome, Pfeiffer syndrome, trisomy 13, trisomy 18, trisomy 21, triploidy)
- Alexander disease
- Mucopolysaccharidoses (e.g., type II (Hunter), type VI, (Maroteaux-Lamy)
- Migrational disorders/congenital muscular dystrophies (e.g., Miller-Dieker, muscle-eye-brain disease, Fukuyama congenital muscular dystrophy, Walker-Warburg syndrome)
- Achondroplasia
- Neurocutaneous syndromes (e.g., neurofibromatosis type 1, rare)
- Idiopathic
Hydrocephalus - DIAGNOSIS
Hydrocephalus - signs & symptoms
Hydrocephalus - history
Presenting concerns:
- Infants: Enlarging head, irritability, vomiting, somnolence, poor feeding
- Older children: Headache, vomiting, double vision, somnolence
Hydrocephalus - physical exam
- Vital signs: In advanced acute hydrocephalus, Cushing triad (hypertension, reflex bradycardia, respiratory irregularities): This is not generally seen in infants prior to fusion of the sutures.
- Rapidly increasing head circumference in infants. Fullness of the anterior fontanelle neither sensitive nor specific, but should be noted. May observe splaying of the sutures.
- Mental status: Irritability or somnolence in infants, behavioral changes in children (acute or chronic)
- Cranial nerves: “Setting sun” sign due to paralysis of upgaze, disconjugate gaze, papilledema, optic atrophy, and visual changes in the chronic setting
- Motor: Gait ataxia; spastic paraparesis in chronic hydrocephalus related to pressure on white matter tracts surrounding the ventricles
- Reflexes: Increased in chronic hydrocephalus
Hydrocephalus - tests
Hydrocephalus - imaging
- Head ultrasound:
- Standard screening test for neonates with suspected hydrocephalus or intraventricular hemorrhage
- Anterior fontanelle must be patent for this test.
- Demonstrates ventricular size, presence or absence of blood, associated structures, and anomalies
- Unenhanced CT of the brain:
- Mainly used in infants and children whose anterior fontanelles have closed and following shunt procedures
- Better visualization of 4th ventricle/brainstem and calcifications than with ultrasound; standardized technique that is less operator-dependent; better availability in the emergency room setting
- MRI:
- Definitive test for analyzing brain anatomy
- Can identify posterior fossa developmental malformations such as Chiari and Dandy-Walker
- Not indicated in acute hydrocephalus, especially when patient is unstable
- New techniques such as diffusion tensor imaging may help to estimate local pressure on white matter adjacent to ventricles, as a correlate of increased intracranial pressure. This may help identify increased intracranial pressure in patients with unchanged ventricular size and aid in the assessment of postsurgical outcome.
Head CT often will not show developmental malformations that may accompany hydrocephalus. MRI is the imaging procedure of choice for elective study.
Hydrocephalus - differencial diagnosis
- Other causes of macrocephaly:
- Familial macrocephaly
- Pericerebral effusions
- Congenital anomalies of intracerebral or extracerebral veins
- Tumors, intracranial cysts
- Primary megalencephaly, hemimegalencephaly
- GM2 gangliosidosis
- Some leukodystrophies (e.g., Alexander disease, Canavan disease)
- Head-sparing intrauterine growth retardation (relative macrocephaly)
- Rapid catch-up growth following prolonged malnutrition
- Other causes of ventriculomegaly, typically with normal head circumference: Brain atrophy and chronic ethanol or corticosteroid exposure (reversible)
- In benign external hydrocephalus, both the ventricles and extra-axial CSF spaces are proportionately enlarged, and macrocephaly is common. Almost always asymptomatic and resolves spontaneously.
Hydrocephalus - TREATMENT
Hydrocephalus - surgery
Acute interventions:
- Ventricular shunt:
- Indication: Progressive or acute symptomatic hydrocephalus
- Contraindications: Active central nervous system infection, active intraventricular hemorrhage, and poor overall prognosis
- Components: Ventricular catheter, reservoir (target of shunt taps), valve, distal catheter
- Distal sites: Peritoneum is the most common choice; pleura, ureter, venous system, gallbladder, and right atrium are other options.
- Approach: Usually performed as an open procedure; endoscopic procedures available in some centers
- Complications:
- Shunt failure occurs in 40% of shunts within the 1st year after placement, and 50% within the 1st 2 years. Causes are obstruction, infection, disconnection, or fracture of components; migration of shunt components; overdrainage; erosion into an abdominal viscus. Presents with symptoms similar to those of acute hydrocephalus.
- Infections occur at a rate of ~8–10% per shunt manipulation, usually during the 1st 6 months after surgery. Presents with low-grade persistent fever, and less commonly with erythema of overlying skin. Most common organism is staphylococcus epidermidis; reinfection occurs in 30% of patients harboring this organism.
- Siphon effect: Drop in ventricular pressure on sitting or standing causing headache; newer shunt systems with antisiphon mechanisms are available.
- Newer shunts have programmable valve mechanisms; one must be cautious when obtaining an MRI in patients with this type of shunt in place as the magnet may affect valve settings.
- Timing of shunt placement is critical and problematic: Sometimes watchful waiting can obviate the procedure, whereas waiting too long may result in brain damage.
- Posthemorrhagic hydrocephalus (PHH) in the neonate may be managed initially with serial lumbar puncture; this has been shown to improve cerebral perfusion in these patients. Most do not require shunt placement. Ultimately some may require ventriculosubgaleal or ventriculoperitoneal shunts.
- 3rd ventricle fenestration (3rd ventriculostomy):
- Current status: New endoscopic techniques make this procedure useful in selected cases.
- Indications: Most effective for obstructive hydrocephalus due to aqueductal stenosis or space-occupying lesions
- Complications: Overall rate of serious complications 9.4%; these include infection, CSF leak, neurologic deficits, extraparenchymal hemorrhage; rare risk of damage to the basilar artery
- Don’t assume hydrocephalus is “cured.” Late shunt failure may occur years after placement, often due to fracture of tubing, and can result in death from acute hydrocephalus causing herniation.
Hydrocephalus - FOLLOW UP
- When the etiology or need for shunt placement is unclear, it is important to follow clinical status, head circumference, and ventricular size (by head ultrasound or CT).
- Chronic hydrocephalus is often accompanied by spastic paraparesis, visual problems, and learning problems.
- Most interventions are supportive:
- Physical therapy, occupational therapy, and orthopedic therapies for spasticity; interdisciplinary cerebral palsy clinics can be critical in providing easy access to these resources.
- Special education programs may be appropriate for children with severe developmental delay.
- It is important for long-term patients in intensive care nurseries to have head circumferences recorded at least twice weekly. Macrocephaly is not always obvious on visual inspection.
- Absence of papilledema does not exclude chronic increased intracranial pressure.
Hydrocephalus - prognosis
Depending on the severity and cause of hydrocephalus, efficacy of treatment, and the presence or absence of concomitant neurologic disorders, outcome may vary widely from normal neurologic development to severe impairment or death.
Hydrocephalus - complications
- Acute hydrocephalus: Herniation syndromes may be fatal.
- Chronic hydrocephalus:
- Macrocephaly
- Spastic paraparesis may lead to gait and motor problems.
- Vision loss
- Developmental delay
- Precocious puberty due to pressure on the hypothalamus
Hydrocephalus - bibliography
- Assaf Y, Ben-Sire L, Constantini S, et al. Diffusion tensor imaging in hydrocephalus: Initial experience. Am J Neuroradial. 2006;27:1717–1724.
- Browd SR, Ragel BT, Gottfried ON, et al. Failure of cerebrospinal fluid shunts: Part I: Obstruction and mechanical failure. Pediatr Neurol. 2006;34:83–92.
- Browd SR, Ragel BT, Gottfried ON, et al. Failure of cerebrospinal fluid shunts: Part II: Overdrainage, loculation, and abdominal complications. Pediatr Neurol. 2006;34:171–176.
- Drake JM, Kestle JR, Tuli S. CSF shunts 50 years on—past, present and future. Childs Nerv Syst. 2000;16:800–804.
- Partington MD. Congenital hydrocephalus. Neurosurg Clin North Am. 2001;12:737–742, ix. 2006;27:1717–1724.
Parent Internet Information: National Hydrocephalus Foundation, http://www.nhfonline.org.- Soul JS, Eichenwald E, Watter G, et al. CSF removal in infantile posthemorrhagic hydrocephalus results in significant improvement in cerebral hemodynamics. Pediatric Res. 2004;55:872–876.
Hydrocephalus - CODES
Hydrocephalus - icd9
- 331.3 Communicating hydrocephalus
- 331.4 Hydrocephalus (acquired) (external) (internal) (malignant) (noncommunicating) (obstructive) (recurrent)
Hydrocephalus - FAQ
- Q: When does an infant need a head ultrasound?
- A: Any infant whose head circumference increases by more than a quartile on the growth chart. Preterm infants below a certain gestational age or birth weight (varies from hospital to hospital) should all receive screening head ultrasounds while in the intensive care nursery.
- Q: When should an infant or child receive an MRI rather than an ultrasound or CT?
- A: Although MRI may be superior in many cases, the logistics of ordering the proper sequences and the need for sedation or anesthesia for long studies must be strongly considered. Consultation with a neurologist or neurosurgeon is generally advised.
- Q: What is the workup for shunt obstruction and shunt infection?
- A: Symptoms and signs of increased intracranial pressure should lead to a neurosurgical evaluation; the most useful studies include head CT (to assess ventricular size and placement of ventricular catheter) and shunt series (plain films of the entire shunt system to check for disruptions). “Pumping” the shunt reservoir is a procedure with a low positive predictive value for shunt failure. Tapping the shunt to assess pressure must be done with discretion, as repeated taps may disrupt the valve mechanism. Fever is the most important indication for a shunt infection evaluation (shunt tap with CSF cell count, protein, glucose, gram stain, and culture). Often patients will be evaluated for both complications.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
More About Pseudotumor Cerebri
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Medical Books Excerpts
- Hypertension
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
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- Papilledema
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
- Hypertension
- "The Diagnostic Approach to Symptoms and Signs in Pediatrics" (2006)
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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» Next page: Hypertension (The 5-Minute Pediatric Consult)
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