hydrocephalus, clinical features in various age groups, investigations, treatment options to create a basic understanding of the underlying pathology and management

1. HYDROCEPHALUS
Dr. Rahul Jain
SR Neurosurgery
DEPTT OF NEUROSURGERY
AIIMS PATNA

2. CSF Physiology
• It circulates within the subarachnoid space, between
the arachnoid and the pial membranes.
• Function as a shock absorber for the CNS, may also
serve an immunological function analogous to the
lymphatic system.
• 80% of CSF is produced by the choroid plexuses,
located in both lateral ventricles (accounts for ≈95% of
CSF produced in the choroid plexuses) and in the 4th
ventricle.
• CSF is also produced by the ependymal lining of the
ventricles, and in the spine, in the dura of the nerve
root sleeves

3. • Average Total CSF volume in the body is 150 ml. CSF
is produced at rate of 0.3 ml/min (450 ml/24 hrs).
• Absorbed primarily by arachnoid villi (granulations)
that extend into the dural venous sinuses. Other
sites of absorption include the choroid plexuses
and glymphatics. The rate of absorption is pressure-
dependent.

5. Hydrocephalus
• An abnormal accumulation of cerebrospinal fluid
within the ventricles of the brain.
• Estimated prevalence: 1–1.5%.
• Hydrocephalus (HCP) is either due to subnormal
CSF reabsorption or, rarely, CSF overproduction.
• subnormal CSF reabsorption. Two main functional
subdivisions:
• 1. obstructive hydrocephalus (AKA non-communicating):
block proximal to the arachnoid granulations (AG).

6. • 2. communicating hydrocephalus (AKA non-obstructive):
defect in CSF reabsorption by the Arachnoid
granulations.
• CSF overproduction: rare. As with some choroid
plexus papillomas.

8. Signs and Symptoms
sun-setting appearance of the eyes - this latter clinical sign is attributed to pressure on
the mid-brain tectum by CSF in the supra-pineal recess

10. • Prior to closure of the cranial sutures and
obliteration of the fontanelle, hydrocephalus
results in disproportionate head growth.
• Thus, over the first 2–3 years of life, measurement
of the occipito-frontal circumference and plotting
this on a centile chart provides a simple and
sensitive test.
• Clinical symptoms are often subtle and include
general irritability, poor feeding and slow
attainment of milestones.

12. Other Signs
• Macewen’s sign: cracked pot sound on percussing
over-dilated ventricles
• 6th nerve (abducens) palsy: the long intracranial
course is postulated to render this nerve very
sensitive to pressure.
• beaten copper skull (some refer to beaten silver
appearance) on plain skull X-ray

13. Radiological Diagnosis
1. the size of both
temporal horns (TH)
is ≥ 2mm in width
2. Evans ratio or index:
ratio of FH to
maximal biparietal
diameter (BPD)
measured in the
same CT slice: > 0.3
suggests
hydrocephalus

14. Other radiological features
1. ballooning of frontal
horns of lateral
ventricles (“Mickey
Mouse” ventricles)
2. periventricular low
density on CT
3. sagittal MRI may
show upward bowing
of the corpus
callosum

15. Management
Medical treatment
• HCP remains a surgically treated condition.
Acetazolamide (Carbonic Anhydrase Inhibitor) may
be helpful for temporizing the condition.
• watch for electrolyte imbalance and acetazolamide
side effects: lethargy, tachypnea, diarrhea,
paresthesias (e.g. tingling in the fingertips)

16. SURGICAL
• Goal - Normal sized ventricles are not the goal of
therapy, Goals are optimum neurologic function
(which usually requires normal intracranial
pressure) and a good cosmetic result.

17. Surgical options
Options include
• third ventriculostomy: currently, endoscopic method is
preferred
• Shunting: VP shunts, VA shunt, ventriculopleural, LP
shunt
• eliminating the obstruction: e.g. opening a stenosed
Sylvian aqueduct. Often higher morbidity and lower
success rate than simple CSF diversion with shunts,
except perhaps in the case of tumor
• choroid plexectomy

20. QUESTIONS

21. Question 1
Which one of the following is the most common
cause of congenital hydrocephalus?
A. Craniosynostosis
B. Intra uterine meningitis
C. Aqueductal stenosis
D. Malformations of great vein of Galen

22. Question 2
Which of the following is expected after
subarachnoid hemorrhage over the convexities of
the brain?
1. increased reabsorption of CSF by arachnoid villi
2. noncommunicating hydrocephalus
3. communicating hydrocephalus
4. increased production of CSF

23. Question 3
The following statements concern cerebrospinal fluid
(CSF) formation: (which is correct)
(a) None of the fluid originates from the brain substance.
(b) lt ls largely formed by the choroid plexuses.
(c) It ls passively secreted by the ependymal cells
covering the choroid plexuses.
(d) It is produced continuously at a rate of about 5
ml/min.
(e) It is drained into the subarachnoid space fromthe
lymphatic vessels of the brain and spinal cord.

24. Question 4