Hydrocephalus Flashcards
Definition
- Excessive accumulation of CSF with enlargement of cerebral ventricles with or without increase of the intra cranial pressure; ICP
- Hydrocephalus is not a specific disease; it represents a diverse group of conditions that result mainly from impaired circulation and/or absorption of CSF .
Normal CSF circulation:
CSF amount in infant = 50 ml (150 in adult)
Normal circulation of csf
- CSF is formed by active secretion by choroids plexus mainly in the lateral ventricles
- CSF passes via foramen of Monro to the 3 rd ventricle
- Then via aqueduct of Sylvius to the 4 th ventricle
- Then via foramena of Lnuscka & Magendi to the subarachnoid space
- CSF in subarachnoid space is absorbed by arachnoid villi to dural venous sinuses
Causes of hydrocephalus
I. Relative hydrocephalus: Normotensive hydrocephalus
- Apparent increase in CSF due to brain atrophy
- Not associated with raised ICP
Causes of A. Obstructive hydrocephalus
Obstructed CSF flow within the ventricular system (Non-communicating)
- 💔Obstruction of aqueduct of Silvius:
* Congenital atresia:
- May be sex linked recessive.
- May be associated with spina bifida occulta * Obstruction from outside by:
- Brain tumors.
- Malformation of vein of Galen (‘listen for A cranial bruit).
- Obstruction from inside:
- Post hemorrhagic (especially in premature).
- Post meningitis (T.B., pneumocci, mumps)
2. Congenital atresia of: - Foramen of Monro.
- Foramina of Luscka & Magendi: Cystic dilatation of 4 th ventricle usually with cerebellar vermis agenesis (Dandy Walker malformation)
3. Arnold Chiari malformation:
Congenital downward displacement of cerebellum, pons & medulla
- Congenital infection especially toxoplasmosis
- Brain tumors
Causes of Non obstructive hydrocephalus (Communicating) due to either:
- Defective CSF absorption * Subarachnoid space adhesions: - Post hemorrhagic or post meningitic * Leukemic infiltration.
* Dural sinus thrombosis - Excessive CSF secretion (Rare) due to:
- Choroid plexus papilloma
- Choriod plexus congestion as in meningitis
Head signs
- Accelerated rate of enlargement of the head is the most prominent sign. (increasing head circumference on serial measurements)
- Fontanels are widely opened & bulging.
- Sutures are widely separated.
- Dilated scalp veins.
- Eyes deviated downwards p Sunset appearance
- Skull percussion p Cracked pot sound (Macewen sign).
- Craniotabes in all bones
- A foreshortened occiput suggests Chiari malformation, and a prominent occiput suggests the Dandy-Walker malformation.
In older child
Marked neurologic manifestations as the sutures are not easily separated with subsequent marked increase ICP
- Bursting headache; severe in the morning
- Blur of vision
- Projectile vomiting (unrelated to meals, not preceded by nausea)
- Bradycardia & hypertension (Cushing response)
Diagnosis Diagnosis
1- clinical picture 2- cranial X-ray 3- head ct & MRI 4-Trans fontanel cranial us 5- CSF examination 6-Fundus examination
TX
1- medical → Carbonic anhydrase inhibitors; acetazolamide
2- surgical → Choroid plexectomy or diathermy for choroid papilloma
- Extra cranial shunt operation
Complications of the shunt
- Shunt nephritis
- Obstruction
- Infection commonly with staph epidermidis (fever, headache, meningismus)
- Relative shortening as the child grow