Interactive Tutorial: Hydrocephalus & Paediatric Neurosurgery Flashcards
CSF production + flow
Choroid plexus (Floor of Lateral ventricle + Roof of 3rd ventricle)
—> Foramen Monro
—> 3rd ventricle
—> Aqueduct
—> 4th ventricle (bounded by Brainstem anteriorly + Cerebellum posteriorly)
—> Foramen Magendie (posterior) + Foramen Luschka (lateral)
—> Basal cistern
—> Spinal canal
—> Venous sinuses (Superior sagittal sinus —> Transverse sinus —> Sigmoid sinus)
—> SVC
Hydrocephalus
Types:
1. Communicating
- Decrease CSF absorption
—> Meningitis
—> Haemorrhage
—> Leptomeningeal spread from tumour
- Increase CSF production
—> Choroid plexus tumour
—> Choroid plexus hypertrophy
- Obstructive
- Obstruction to CSF flow
—> Posterior fossa tumour (esp. in paediatrics)
—> 3rd ventricle tumour
Clinical features:
1. Increase head circumference
- big head that cross percentile
2. Full / Tense fontanelle (normally should be soft + pulsatile)
3. Developmental delay
Investigations:
1. USG brain (only doable with an acoustic window i.e. fontanelle)
2. CT brain (advantage: quick to finish so children movement is not an issue i.e. no need sedation, disadvantage: radiation)
3. MRI brain
First sign of hydrocephalus:
- Ballooning of 3rd ventricle
Reduce CT radiation
- Use clinical judgement
- observe for 12 hours (head injury usually improve within 12 hours) rather than doing CT scan for every patient - USG / MRI to replace
- Adjust scan parameter i.e. Special CT protocol for children to tune down radiation exposure
CSF diversion
- Extracranial shunting (Divert to another body compartment)
- Ventriculo-peritoneal shunt (peritoneal cavity good for absorbing large amount of fluid)
- Ventriculo-atrial shunt (precaution: introducing infection into systemic circulation directly —> Shunt nephritis)
- Ventriculo-pleural shunt (last resort since not good at absorbing large amount of fluid + impair lung function due to pleural effusion, only done as temporary measure) - Intracranial shunting
- Endoscopic 3rd ventriculostomy
—> can be used for blocked shunt apart from obstructive hydrocephalus
Structure of CSF shunt
- Ventricular catheter
- Valve
- One way valve: allow only one way flow to prevent backflow of potential dirty fluid in peritoneum go back into brain + pressure regulating purpose: only open when certain pressure is reached to avoid overshunting + siphoning effect —> intracranial hypotension
Complications of Extracranial shunting
- Malposition
- Blockage
- catheter only 2mm diameter —> easily blocked
- valve pumping (i.e. pressing on valve) not accurate / sensitive / specific
- history / clinical examination
- shuntogram (X-ray of skull, CXR, abdomen to see total integrity of shunt)
- baseline scan (CT brain after inserting shunt for ~6 months for appearance of baseline normal ventricle —> compared to subsequent scans of same child)
- partial blockage —> pressure build up —> relieve headache —> intermittent headache - Infection
- presentation:
—> Sepsis
—> ↑ ICP due to blocked shunt
—> Abdominal distension (∵ pseudocyst formation to wall off infection)
- tapping of shunt in septic patient
- treatment:
—> Antibiotics
—> Removal of hardware
—> New shunt - Slit ventricle syndrome
- nightmare for neurosurgeon and patient
- low pressure valve inserted early in life —> changes compliance of brain —> slight change in volume —> rapid change in ICP —> rapid deterioration
Head injury: Birth trauma
Types of bleeding:
1. Caput succadaneum
2. Cephalhaematoma
- bleeding from skull —> confined within periosteum —> may not resolve due to surrounding bone formation
3. Subgaleal haematoma
4. Epidural haematoma
Management:
- Rarely require surgical intervention
- Treated conservatively
- FU with cranial USG / MRI
- Avoid repeated CT scan
Pay attention in newborn:
- Small blood volume —> small blood loss can already lead to haemodynamic compromise
Infants head injury
- High incidence around 6 months old (start to be able to roll over)
- Watch out for non-accidental injury
- Admit for observation
- Explain to parents about radiation risk of CT
Investigations:
- Skull X-ray (rare now ∵ shown to have no correlation with underlying brain injury)
- USG
- CT scan (CATCH rule)
CATCH rule:
1. GCS <15 at 2 hours after injury
2. Suspected open / depressed skull fracture
3. History of worsening headache
4. Irritability on examination
5. Any signs of basal skull fracture (e.g. haemotympanum, raccoon eyes, CSF otorrhoea / rhinorrhoea, Battle’s sign)
6. Large, boggy haematoma of scalp (indicating skull fracture)
7. Dangerous mechanism of injury (e.g. motor vehicle crash, fall from >=3 feet, fall from bicycle with no helmet)
Complications:
1. Traumatic pseudoaneurysm (ligate + excise / glue injection)
Stroke
Principle of management:
1. Prevent secondary insult
- ↑ ICP
- Hypotension
- Hypertension
- Hypercapnia
- Hyperthermia
- Seizure
Intracerebral haemorrhage
Causes:
1. Cerebral aneurysm (rare)
2. Vascular tumour
3. AV malformation (bleeding risk 2-4% per year)
- Moyamoya disease
—> Progressive ICA occlusion causing new abnormal blood vessels formation which is prone to bleeding (Children: Cerebral ischaemia, Adult: Cerebral haemorrhage)
—> Treatment: Bypass surgery with superficial temporal artery
Treatment:
1. ICP control
- Clot evacuation
- CSF drainage
- Definitive
- Excision
- Embolisation
- Stereotactic surgery
Paediatric brain tumour
Types:
1. Astrocytoma
2. Supratentorial ependymoma
3. Optic glioma
4. Craniopharyngioma
5. Brainstem glioma
6. Medulloblastoma
7. Cerebellar astrocytoma
8. Infratentorial ependymoma
9. Pinealoma
Adult vs Paediatric brain tumour:
- Adult: 70% cerebrum, 30% cerebellum / brainstem, majority brain metastasis
- Paediatric: 70% posterior fossa, 30% cerebrum
Clinical features:
1. Obstructive hydrocephalus —> ↑ ICP
2. Vomiting, malaise, sleep disturbance
Management principle:
1. Need detail clinical examination + High index of suspicion
2. Different from adult brain tumour
3. Multidisciplinary approach
- Paediatric oncologist
- Radiation oncologist
- Neurosurgeon
- Neurologist
- Endocrinologist
- Nurses
- Clinical psychologist
- PT / OT / ST
4. Team decision from very start
5. Protocol driven: International studies
Treatment:
1. Surgery
- Tissue for diagnosis (exception: Germ cell tumour (∵ diagnosis can be made on MRI, respond well to chemotherapy), Diffuse intrinsic pontine glioma (DIPG) (∵ deadly regardless))
- Gross total resection ideally: balance prognosis vs morbidity
- Debulking, shunts, reservoirs for tapping cyst (symptomatic control / ICP reduction, therapy)
Parinaud syndrome (Dorsal midbrain syndrome) due to Hydrocephalus
- Paralysis of up gaze —> Sunset eyes
- ∵ hydrocephalus compress on dorsal tectal plate (superior + posterior part of brainstem)
- compression of vertical gaze center at rostral interstitial nucleus of medial longitudinal fasciculus (riMLF) (from JC021) - Pseudo-Argyll Robertson pupils
- accommodation reflex is present but light reflex is absent - Convergence-Retraction nystagmus (鬥雞nystagmus)
Craniosynostosis
Skull growth mainly secondary to brain growth:
- 40% adult size at term
- 85% adult size by 1 yo
- 95% adult size by 6 yo
Sutures allow growth perpendicular to them —> Growth at suture lines related to brain growth
Suture closure:
- Posterior fontanelle: 3-6 months
- Anterior fontanelle: 9-18 months
- Coronal, Sagittal, Lambdoid suture: 40 yo
Syndromic craniosynostosis:
- 10-20% of cases
- Autosomal dominant (chromosome 10q)
- Multi-sutural, complex cases
- If a suture is fused —> Check hands, feet, big toe, thumb
Plagiocephaly
Causes:
1. Deformational / Positional (i.e. Lying on one side of head)
- Ipsilateral head / ear will be displaced anteriorly (∵ head growth not affected) —> Head will be parallelogram in shape (Ipsilateral frontal bossing)
- Lambdoid suture craniosynostosis
- Ipsilateral head will be shorter / ear displaced posteriorly —> Head will be trapezoid in shape
Chiari malformation (aka Arnold–Chiari malformation)
- Most common cause of syringomyelia
Pathophysiology:
- Lack of development of posterior fossa
—> cerebellar tonsils herniate through foramen magnum into upper cervical spine
—> obstruction of CSF flow between brain and spine
—> increase flow in CSF space outside spinal cord
—> venturi effect
—> low pressure system
—> cause CSF space within central canal of spinal cord to expand
—> syringomyelia
Clinical features:
- UL weakness, numbness, scoliosis, back pain
Treatment:
- Suboccipital craniectomy —> allow more space for CSF to flow
