Hydrocephalus

Question 1

Definition

Answer 1

• EXCESS CSF W/I INTRACRANIAL SPACE - particularly INTRAVENTRICULAR SPACES W/I BRAIN
  
  • Causes DILATION OF VENTRICLES + WIDE RANGE OF SYMPTOMS

Question 2

Investigations

Answer 2

CT

	○ DILATION OF TEMPORAL HORNS OF LATERAL VENTRICLES - in most young & middle-aged pt. should be invisible

	○ 3RD VENTRICLE BALLOONED
	○ ↑ LATERAL VENTRICLE SIZE
	○ PERIPHERAL SULCI EFFACED

	○ EVANS RATIO > 30%/VENTRICULAR INDEX > 50% (remember pt. hay have pre-existing enlarged ventricles that are normal)

Question 3

Management

Answer 3

Surgical

Acute hydrocephalus (CoH + NCH):

URGENT/EMERGENT placement of EXTERNAL VENTRICULAR DRAIN

* Pt. may need permanent shunt
* High infection risk

Communicating hydrocephalus:

SHUNT PLACEMENT

* Most used = VENTRICULO-PERITONEAL
* Sometimes = lumbar-peritoneal (problem w/ overdrainage)
* Ventriculo-atrial = when peritoneal failure occurs
* acute pt. may manage w/ EVD w/ successful weaning - not req. shunt rn, but will eventually

Non-communicating hydrocephalus:

REMOVING OBSTRUCTING LESION, MAY NOT NEED SHUNT

CAN ALSO DO 3RD VENTRICULOSTOMY = often performed w/ VP SHUNT

Question 4

Communicating hydrocephalus: aetiology

Answer 4

• NON-OBSTRUCTIVE = PATHWAY OPEN ALONG ENTIRE CSF PATHWAY
  
  • PRODUCTION > RESORPTION (usually UNDER-RESORPTION)○ Sooo… VENTRICULAR SYSTEM DILATES UNIFORMLY & ↑ ICP
    • INFECTION
    • SUBARACHNOID HAEMORRHAGE (blood products can cause scarring of arachnoid granulations)
    • POST-OPERATIVE
    • HEAD TRAUMA
    • IDIOPATHIC
  • Etc.
  • V. RARE = CSF OVERPRODUCTION - occurs in CHOROID PLEXUS PAPILLOMAS

Question 5

Presentation

Answer 5

Children:

• ↑ HEAD CIRCUMFERENCE (+ look for bulging fontanelle)
  
  • disproportional increase, young children where cranial sutures haven’t fused)
• DILATED VEINS
• FAILURE TO THRIVE + POOR FEEDING
• NAUSEA, VOMITING, IRRITABILITY
• UPGAZE DIFFICULTY (sunset phenomenon)
• INCREASED MUSCLE TONE

Adults + children w/ fused sutures:

• SYMPTOMS OF RAISED ICP
  
  • HEADACHE
  • NAUSEA, VOMITING
  • ALTERED CONSCIOUSNESS, COGNITIVE IMPAIRMENT, SOMNOLENCE
  • PAPILLOEDEMA, REDUCED VISUAL ACUITY
  • CRANIAL NN. PALSIES = 3RD, 6TH
  • GAIT DISTURBANCE, UPGAZE DIFFICULTY, SLOWLY PROGRESSING DEMENTIA

Question 6

Non-communicating hydrocephalus: aetiology

Answer 6

OBSTRUCTING = ANY PHYSICAL OBSTRUCTION TO NORMAL CSF FLOW
• AQUEDUCTAL STENOSIS = most common in children
• TUMOURS/CANCERS/MASSES = most common in adults
• CYSTS
• INFECTION
• HAEMORRHAGE/HAEMATOMA
• CONGENITAL MALFORMATION/CONDITIONS

Question 7

Normal pressure hydrocephalus - presentation, investigations, management

Answer 7

PRESENTATION:

* URINARY INCONTINENCE
* GAIT DISTURBANCE (usually 1st to appear): WIDE STANCE, SHORT SHUFFLING STEPS
* RAPIDLY PROGRESSIVE DEMENTIA

INVESTIGATIONS:

* CT/MRI = COMMUNICATING HYDROCEPHALUS
* LUMBAR PUNCTURE:

	○ NORMAL OPENING PRESSURE

	○ SYMPTOMS IMPROVE W/ CSF REMOVAL

• GAIT ASSESSMENT (TIME WALK & TURNS) + MMSE

MANAGEMENT: PROGRAMMABLE VP SHUNT

Question 8

CSF production + resorption

Answer 8

MAJORITY PRODUCED BY CHOROID PLEXUS

* ACTIVE PROCESS REQ. ATP
* Na+ PUMPED INTO SUBARACHNOID SPACE + H2O FOLLOWS from blood vessels

* AVERAGE ADULT PRODUCES ~ 450 - 600cc EVERYDAY (cubic centimetre; 1cc = 1mL)
* ONLY ~ 150cc PRESENT IN AVERAGE ADULT AT ANY GIVEN MOMENT - of which ONLY ~ 25cc W/I BRAIN VENTRICLES

• Sooo… PRODUCTION = RESORPTION & THIS IS V. FINELY CONTROLLED - EVEN A SMALL INSULT/INJURY CAN CAUSE HYDROCEPHALUS

ABSORBED BY ARACHNOID GRANULATIONS, containing ARACHNOID VILLI into VENOUS SINUSES - mainly SUPERIOR SAGITTAL SINUS

* ARACHNOID VILLI = PRESSURE DEPENDANT ONE-WAY VALVES; OPEN WHEN INTRACRANIAL PRESSURE ~ 3-5cm H2O > DURAL VENOUS SINUS PRESSURE
* PASSIVE PROCESS DRIVEN BY PRESSURE GRADIENT