⁨⁨⁨⁨⁨أسئلة الثامنة جراحة رابعة دمياط (نيورو)

• Surgery is the topic
• The cost is 10 LE
• Level 4
• Neurosurgery is the subtopic
• Hydrocephalus is covered
• The number 8 is visible

Hydrocephalus Definition

• Results from an imbalance of CSF formation and absorption, leading to fluid accumulation in the ventricular system.
• Defined as a pathological condition involving a disturbance in CSF production, circulation, or absorption.
• Accumulation of CSF occurs within the fluid-filled compartments of the brain, which are the ventricles.

Anatomy of the Ventricular System

• Key components:
  • Lateral ventricles
  • Third ventricle
  • Fourth ventricle
  • Foramina of Monro
  • Cerebral aqueduct
  • Central canal
  • Anterior horns of lateral ventricles
  • Inferior horns of lateral ventricles

CSF Circulation

• Secretion: Choroid plexus produces CSF at approximately 20 ml/hr.
• Circulation:
  • CSF flows from lateral ventricles to the Foramina of Monro.
  • Then to the 3rd ventricle, Aqueduct of Sylvius, and 4th ventricle.
  • CSF moves through the foramina of Luschka & Magendie.
  • Flows into the subarachnoid space, surrounding the brain & spinal cord.-
• Absorption from arachnoid granulations into the venous system.

Hydrocephalus Classification

• According to obstruction level: includes obstructive and non-obstructive types
• According to presentation age: includes congenital and acquired types
• According to onset: includes acute and chronic types
• According to activity: includes hydrostatic, compensated and arrested types

Communicating vs. Obstructive Hydrocephalus

• Communicating Hydrocephalus:
  • CSF circulation is blocked at the level of arachnoid granulations.
  • Causes include increased CSF production from choroid plexus papilloma.
  • Impaired CSF absorption due to blocked arachnoid villi in subarachnoid spaces from subarachnoid hemorrhage, intraventricular hemorrhage, or meningitis.
  • Venous drainage insufficiency from superior sagittal sinus thrombosis.
• Obstructive Hydrocephalus:
  • CSF circulation is blocked proximal to the arachnoid granulations.
  • Impaired circulation due to anatomical block
  • Causes include block of foramen of Monro, leading to enlarged lateral ventricles.
  • Also block in aqueduct of Sylvius, enlarging the lateral and 3rd ventricles.
  • Block in foramina of Luschka & Magendie, enlarging all ventricles.

Congenital vs. Acquired Hydrocephalus

• Congenital Hydrocephalus:
  • Present at birth.
  • Caused by environmental influences during fetal development or genetic predisposition.
• Acquired Hydrocephalus:
  • Develops around the time of birth, or at some point afterward.
  • Can affect individuals of all ages.
  • May be caused by injury or disease.

Etiology of Hydrocephalus

• Congenital Causes:
  • Chiari type II malformation, often accompanied by myelomeningocele.
  • Chiari type I malformation.
  • Aqueductal stenosis (primary: congenital narrowing or septa; secondary aqueductal gliosis from intrauterine infection or germinal matrix Hg.).
  • Dandy-Walker malformation, due to atresia of foramina of Luschka and Magendie.
• Acquired Causes
  • Post-infection is the most common cause of communicating hydrocephalus, specifically purulent & basal meningitis, including TB.
  • Post-hemorrhagic: Post-SAH early and late or post-intraventricular hemorrhage.
  • Secondary to masses: Non-neoplastic (e.g., vascular malformation) or neoplastic.
• Neoplastic Causes
  • Produce obstructive hydrocephalus by blocking the CSF pathways.
  • Foramen of Monro block, such as by a colloid cyst.
  • 3rd ventricle block, such as by suprasellar tumors, craniopharyngioma, or pituitary tumors.
  • Aqueduct of Sylvius block, such as by medulloblastoma.
  • 4th ventricular wall block, such as by ependymomas.
  • Outside the ventricles wall block, caused by primary or secondary brain tumors.
• Other Causes
  • Post-operative complications.
  • Post-traumatic injuries.
  • Associated with spinal tumors.

Clinical Presentation

• Infants
  • Increased head size above the normal percentile.
  • Bulging and tense fontanelles.
  • "Setting Sun" eyes (Eyes deviated downward)
  • Upward gaze palsy from pressure on the suprapineal recess.
  • MacEwen's signs: cracked pot sound over dilated ventricles.
  • Separated sutures.
  • Poor head support.
  • Prominent scalp veins due to reversal of flow from IC sinuses.
  • Lethargy or irritability.
  • Seizures.
  • Irregular respiration with apneic spells.
• Older Children & Adults: Signs of Increased Intracranial Pressure (ICP)
  • Persistent vomiting.
  • Headache.
  • Visual problems.
  • Lethargy and behavior changes.
  • Difficulty with school work.
  • Seizures, abducent nerve palsy.
  • Decreased mental function.
  • Delayed movements.
  • Difficulty in feeding & excessive sleepiness.
  • Neurological deficit caused by underlying etiology.

Diagnosis

• Transillumination test: Advanced cases of hydrocephaly produce a glow of light over the entire cranium.
• Diagnostic methods:
  • Clinical evaluation
  • Ultrasound (intrauterine & through fontanels)
  • Skull X-rays
  • CT scan of the brain
  • MRI of the brain

CT & MRI Criteria for Hydrocephalus

• CT & MRI Criteria Suggestive of Hydrostatic Hydrocephalus
  • Ventriculomegaly.
  • The following structures are not visible:
    • The Sylvian fissure
    • Interhemispheric fissure
    • Cerebral sulci
    • Basal cisterns
  • The size of both temporal horns is > 2mm in width.
  • Periventricular low density on CT.
  • Periventricular high intensity signal on T2WI on MRI.
  • Ballooning of the frontal horn of the lateral ventricles & 3rd ventricles.
  • Evans ratio (Ratio of frontal horns to maximal bipartial diameter > 30%).
  • Sagittal MRI may show upward bowing of the corpus callosum.

Treatment

• Lines of Treatment
  • Surgical: Primary treatment to minimize or prevent brain damage by improving CSF flow.
  • Medical: (Acetazolamide - Furosemide - dehydrating measurers)
  • External Ventricular Drain (EVD) used in cases of post infection & post hemorrhage.
• Surgical Options:
  • Shunting: Ventriculo-peritoneal or ventriculo-atrial.
  • Endoscopic Procedures: Endoscopic 3rd ventriculostomy or choroid plexectomy.
  • Eliminating Obstruction: Aqueductoplasty (in primary aqueductal stenosis) or removal of tumors or blood clots obstructing the CSF path.

Shunting

• Types of Shunts
  • By category: Ventriculo-peritoneal shunt, ventriculo-atrial shunt, lumbo-peritoneal shunt, and others like ventriculo cisternal shunt, ventriculo pleural shunt, ventriculo uretric, and ventriculo amniotic shunt.
  • By gradient pressure: Low pressure valve, medium pressure valve and high pressure valve.
  • By hardware: Tumor filter shunt, anti-siphon device shunt, horizontal/vertical valve, externally programmable variable pressure valves, and on/off device.
• Complications of Shunt Surgery
  • Under shunting & obstruction.
  • Over shunting & subdural hematomas (slit ventricle syndrome).
  • Infection.
  • Disconnection at junction & displacement.
  • Seizures.
  • Problems related to the distal catheter (peritoneal or atrial).
  • Extraneural metastasis.
  • Silicon allergy & skin breakdown over hardware.
  • Craniosynostosis.

Assessment of Shunt

• Clinical Assessment
  • Signs include vomiting, headache, fever, degree of empty & filling in the reservoir, cognitive & intellectual functions, redness along shunt line, fluid around shunt valve, papilledema, and irritability.
• Radiological Assessment
  • Includes plain X-ray of the skull, abdomen and pelvis, and CT brain.

Endoscopic Procedures

• Endoscopic Third Ventriculostomy
  • Primary treatment for aqueductal stenosis.
• Septal Fenestrations
  • For compartmental & multi septated hydrocephalus.
• Cyst Fenestrations
  • Treat intraventricular cysts, arachnoid cysts, or porecephalic cysts.
• Endoscopic Choroid Plexus Coagulation.

Endoscopic Third Ventriculostomy

• Indication: Primary aqueductal stenosis.
• Contraindication: Communicating hydrocephalus.
• Complications:
  • Hypothalamic injury
  • Transient 3rd & 6th nerve injury
  • Uncontrolled bleeding
  • Cardiac arrest
  • Traumatic basilar artery aneurysm.
• Success rate:
  • High success rate (60-90%) for non-tumoral aqueductal stenosis.
  • Low success rate (20%) in infants because they may not have normally developed subarachnoid spaces or if there is pre-existing pathology like a tumor, previous shunt, or previous SAH.

Special Forms of Hydrocephalus

• Hydrocephalus ex vacuo
  • Enlargement of the ventricles due to loss of cerebral tissue (cerebral atrophy).
  • Usually a function of normal aging, but accelerated by certain disease processes such as Alzheimer's.
• Idiopathic Intracranial Hypertension
  • Heterogeneous group of conditions characterized by increased ICP
  • No evidence of: Intracranial mass, hydrocephalus, infection, or hypertensive encephalopathy.
• External Hydrocephalus
  • Enlargement of subarachnoid spaces over the frontal poles in the first years of life; ventricles are normal or minimally enlarged.
  • Should be distinct from: Benign subdural collection of infancy and/or Symptomatic chronic extra-axial fluid collections.
• Normal Pressure Hydrocephalus
  • Classic triad: dementia, gait disturbance, and urinary incontinence.
  • CT or MRI: Communicating hydrocephalus.
  • Random LP: Normal pressure.
• Hydranencephaly
  • Definition: A post-neurulation defect that is a total or near total absence of cerebrum with intact cranial vault and meninges. The intracranial cavity is filled with CSF and there is usually progressive macro-crania.
  • Causes: Usually due to bilateral internal carotid artery infarction and/or congenital or neonatal infection (herpes, toxoplasma).

Distinguishing Maximal Hydrocephalus From Other Conditions

• Hydrocephalus can be distinguished from maximal hydrocephalus based on the following:
  • EEG: No cortical activity in hydranencephaly.
  • CT, MRI, U/S brain: Majority of intracranial space is occupied by CSF; no frontal lobes or frontal horns; remnant of temporal or occipital cortex; posterior fossa structures are intact.
  • Tran-illumination
  • Angiography: No flow through the carotids; normal posterior circulation.
• Entrapped 4th Ventricle
  • Definition: 4th ventricle neither communicates with the 3rd ventricle nor with the basal cisterns.
  • Causes: Usually seen in chronic shunting of the lateral ventricles, especially with post-infectious hydrocephalus, or in those with repeated shunt infection.
  • Treatment: Sometimes needs shunting the fourth ventricle.
• Arrested Hydrocephalus
  • Definition: Compensated hydrocephalus is a condition that would require the presence of CSF shunt.
  • Criteria of diagnosis (in absence of a CSF shunt):
    • Near normal ventricular size.
    • Normal head growth curve.
    • Continued psychomotor development.
    • Clinical follow up for symptoms of intracranial decompensation (headache, vomiting, ataxia, or visual disturbance) is necessary.