Hydrocephalus in Africa: A Surgical Perspective
1. Introduction
Hydrocephalus is the excessive accumulation of cerebrospinal fluid (CSF) within
the cranial vault due to excessive production or inadequate absorption. The
management of hydrocephalus in developing nations is hindered by significant
economic constraints and delays in treatment - most patients in fact do not
present for at least seven months after the onset of clinical symptoms. (1)
CSF shunts are expensive and not always available, but can be used to treat
hydrocephalus regardless of etiology. The management of hydrocephalus and the
complications associated with its treatment require considerable surgical judgment
and a life-long approach to patient follow-up.
2. Demographics
The prevalence and incidence of hydrocephalus in developed nations is estimated
as 0.9-1.2/1000 and 0.2-0.6/1000 respectively.(2) No reliable
estimate is available in the African literature, but its incidence is likely
higher because of untreated / poorly treated neonatal meningitis and nutritional
deficiencies.
3. Etiology & Pathophysiology
CSF is produced predominantly by the choroid plexus of the four cerebral ventricles,
at a rate of 20 mL/hour. It flows via the foramina of Luschka and Megendie into
the subarachnoid space, and is absorbed by the arachnoid villa into the venous
system via the superior saggital sinus.
Hydrocephalus has been categorized as communicating or non-communicating: the
former is due to failure of CSF absorption by the arachnoid villi, whereas the
latter involves obstruction of CSF flow into the subarachnoid space. A small
minority of cases exhibit excessive production of CSF – most commonly
secondary to a choroid plexus papilloma.
In developed nations, hydrocephalus has historically been most commonly due
to myelomeningocele, with the post-hemorrhagic hydrocephalus of prematurity
becoming at least as common in recent years.(2) Some reports
have suggested that in central Africa the most common causes of hydrocephalus
are neural tube defects and congenital aqueductal stenosis. Similarly, in Zambia,
the ratio of congenital to “post-meningitic” hydrocephalus has been
reported to be 2:1. In contrast, well-documented prospective series in East
Africa have shown the etiology of hydrocephalus to be 57% post-infectious, 29%
non-post-infectious, and 13% myelomeningocele. Thus, neonatal meningitis / ventriculitis
is likely the most common cause of hydrocephalus in East Africa.(1)
Despite the prevalence of malaria in Africa and case reports of associated hydrocephalus, there is no clear relationship between its cerebral form and subsequent hydrocephalus.(3) On the other hand the pathophysiology of hydrocephalus in the setting of myelomeningocele is multifactorial: it may be secondary to obstruction at the aqueduct, ventricular outlet, craniocervical junction, or arachnoid granulations.
4. Clinical Presentation
The clinical presentation of hydrocephalus is characterized by signs and symptoms
of increased intracranial pressure (ICP). Symptoms may include: headache, vomiting,
failing vision, drowsiness, fatigue, deteriorating mental function, and enlarged
head circumference. Signs include: wide tense fontanel, papilloedema, reduced
visual acuity, failure of upward gaze (the sunsetting sign), general clumsiness,
dyspraxic gait, and increasing head circumference. Older children will not present
with increased head circumference, and often complain of the classic triad:
headache, vomiting and lethargy.
| Acute | Chronic |
| Headache | Accelerated head growth |
| Nausea/Vomiting | Loss of developmental milestones |
| Lethargy | Difficulty in school |
| Papilloedema | Vision loss |
| CN IV palsy | Gait disturbance |
| Scalp vein distention | |
| Early morning headache | |
| Headache exacerbated by recumbency | |
Table 1. Signs and Symptoms of Increased Intracranial Pressure (2)
5. Investigations
The clinical exam is the most readily available investigation for the diagnosis
of increased ICP, shunt malfunction or infection. All shunts should be examined
and manipulated, although pumping of the shunt is not a reliable test of malfunction.
Nevertheless, classic teaching suggests that a reservoir that is difficult to
depress (or refills instantaneously) may indicate distal obstruction whereas
slow filling of the reservoir may indicate obstruction proximally.(4)
Cranial ultrasonography (US) is an essential diagnostic tool in developing countries:
it can readily assess ventricular size with minimal training, and is relatively
inexpensive. Depending on operator skill, the size of the fourth ventricle can
be assessed on US as a proxy indication of the patency of the aqueduct. This
may be particularly relevant in stratifying patients for treatment with prosthetic
shunts vs. endoscopic third ventriculostomy (ETV).(1) Serial
US imaging may be appropriate in patients with an equivocal presentation of
increased ICP prior to subjecting them to shunt revision. All children with
shunts should be followed up regularly, including baseline US within 3 months
of surgery. Although acute changes from baseline may help in the subsequent
diagnosis of shunt failure, up to a third of patients will not exhibit any evidence
of ventriculomegaly.(4)
Both computed tomography (CT) and magnetic resonance imaging (MRI) are excellent
modalities, but their routine use is prohibited by cost in developing nations.
Nevertheless, CT may be necessary in assessing the ventricular size in older
children with closed fontanels. Evidence of increased ICP in children with closed
fontanels can also be obtained through direct measurement of CSF pressure by
lumbar puncture: the CSF column height is measured in a piece of IV tubing connected
to the spinal needle via a 3-way stopcock.
Although rarely required, a “shuntogram” of the entire radiopaque
shunt tract via a series of plain x-rays encompassing the skull, chest and abdomen
is helpful when there is clinical suspicion of possible shunt migration or discontinuity.(5)
Documentation of shunt infection or ventriculitis may require culturing of CSF
samples from the ventricles (in the neonate) or from the shunt reservoir itself.
There is a small but real risk of CSF contamination with each diagnostic tap.
A value of 50-100 white cells/mm (2) is considered indicative
of an infected CSF, as is elevated protein, decreased sugar, and naturally the
presence of bacteria on Gram stain. A bloody tap may erroneously elevate the
white cell number. Any febrile child with a shunt should be examined for the
possibility of other common febrile illnesses, especially if they are beyond
6 months post-shunt insertion. Malaria, otitis media, and viral gastroenteritis
should be excluded, in addition to the possibility of urinary tract infection
particularly in those with spina bifida and bladder dysfunction.(4)
6. Management
The definitive management of hydrocephalus at present remains surgical. The
diuretic acetazolamide has been shown to decrease CSF production in animal and
human studies (6), but is of temporary benefit and should only
be used in the palliative setting or in equivocal cases until a definitive diagnosis
can be made. It has also been used in post-hemorrhagic hydrocephalus of the
newborn as a temporizing maneuver to avoid shunting.(7)
6.1. Ventriculo-peritoneal shunt
The most common surgical intervention to treat hydrocephalus is the insertion
of a shunt through the skull and cortical mantle into the ventricle, with the
distal catheter placed into a physiologic drainage basin, typically the peritoneal
space (ventriculo-peritoneal or VP shunt). Other sites for CSF diversion include
the right atrium and the pleural space. The advantage of a CSF shunt is that
it is beneficial in nearly all types of hydrocephalus – regardless of
etiology.
CSF shunts usually contain three parts: a ventricular catheter, a valve, and
a distal catheter. Most valves are designed to allow for sampling via needle
puncture. The so-called “differential pressure valves” use the gradient
between the ventricle and the tip of the distal catheter to effect flow. “Medium
pressure” valves are those which drain CSF if the pressure gradient is
> 10 mm HG, and are used most commonly. Although many different valve designs
exist including “siphon limiting”, “flow limiting”,
and “programmable” valves (whose settings can be changed using an
external magnet) there is limited evidence for their benefit. A large randomized
trial demonstrated no difference in time to first shunt failure in the treatment
of children with newly diagnosed hydrocephalus when comparing a standard differential
pressure valve compared to two other higher generation valves.(8)
Similarly, the use of an adjustable shunt was not shown to be of any benefit
in terms of overall survival.(9) Finally, and of most relevance
to the developing world, there is good evidence from a prospective randomized
controlled trial demonstrating that the Chhabra® shunt (made by Surgiwear
in India) is equivalent to its common Western counterpart in incidence of shunt
complications, despite it being almost 1/20th the cost.(10)
The Chhabra shunts are made available for free to qualifying centers through
the International Federation of Spina Bifida and Hydrocephalus (www.ifglobal.org).
In extreme situations, a piece of IV tubing or a sterile Silastic® feeding
catheter can be used as VP shunts, but these non-valved alternatives are associated
with frequent complications and not recommended.
6.2. Alternative CSF Drainage Sites
Pleural shunts are rarely required, but can be placed via the 4th to 6th intercostal
space at the anterior axillary line into the pleural cavity, with care to avoid
placement into lung parenchyma or chest wall. The associated CSF effusion and
iatrogenic pneumothorax resolve conservatively in almost all patients. Ventriculoatrial
shunts are rarely performed because of complications of cor pulmonale, shunt
nephritis, and catheter embolization. They require intraoperative U/S or fluoroscopy
to document catheter placement into the atria via the internal jugular vein.
We do not recommend their use.
6.3. Endoscopic Third Ventriculostomy
The morbidity of the life-long shunt has created interest in the use of endoscopic
third ventriculostomy (ETV) a procedure that can effectively treat hydrocephalus
without insertion of any foreign body. The principles of placement of an ETV
include: frontal access, ventricular cannulation, insertion of a rigid or flexible
neuroendoscope into the 3rd ventricle via the lateral ventricle and the foramen
of Monroe. A fenestration is made in the base of the third ventricle between
the infundibular recess and the mamillary bodies. This is commonly performed
using a combination of electrocautery and a balloon dilator, thus creating a
cerebrospinal fluid fistula between the subarachnoid space and the 3rd ventricle.(5)
More recently, the concurrent performance of cauterization of the choroid plexus
has been introduced as means of increasing shunt avoidance.
Classically, ETV was used for older children or adults with congenital aqueductal
stenosis. Working in Uganda, Dr. Benjamin Warf has convincingly demonstrated
however that ETV is a reasonable option for all children greater than 1 year
of age (irrespective of hydrocephalus etiology) with a shunt avoidance rate
of 80%.(1) In addition, with the use of cranial US and direct
endoscopic visualization of the aqueduct, he stratified younger children based
on aqueductal patency, and has demonstrated 70% success in those < 1 year
of age who have a post-infectious obstruction of the aqueduct. In addition,
the use of ETV in combination with choroid plexus cauterization has increased
shunt avoidance from 35 to 76% in children with myelomeningocele, and from 20%
to 71% in children < 1 year of age with a non-post-infectious hydrocephalus
and an open aqueduct.
Performance of ETV is beyond the scope of this review, and requires adequate
mentoring by an experienced surgical team and significant technical support
for maintaining the endoscopic system. Although the avoidance of a shunt (and
the accompanying morbidity and mortality of shunt failure) in the developing
world is a reasonable goal, the additional safety of ETV has not yet been proven
in the long term, and most authors counsel that the same life-long follow-up
is required in either case.(2)
7. Postoperative Complications
Post-operative complications of shunt insertion can generally be classified
as mechanical or infectious.
7.1. Mechanical Shunt Failure
Mechanical shunt failure can occur through proximal obstruction, distal obstruction,
component separation/fracture/migration or excessive CSF drainage.(2)
Proximal or distal obstruction generally presents with signs and symptoms of
increased ICP, whereas infectious failure presents with fever, redness or swelling
at the surgical site, drainage of pus or CSF from the wound, nuchal rigidity,
abdominal pain or peritonitis. Shunt obstruction in older patients often presents
with headache, and is not associated with pain along the shunt tract.(2)
Although the signs and symptoms of shunt failure have been examined empirically,
there is no ideal diagnostic test.(2) Importantly, the opinion
of parents is of greater diagnostic accuracy than that of referring clinicians:
thus caregivers’ opinions of their child’s shunt function should
not be dismissed lightly. In addition, children tend to present with similar
manifestations during episodes of repeated shunt failure.(11)
Revision of a non-infected, but obstructed shunt should generally be approached
from the cranial incision as obstruction is more common at the ventricular limb,
and both ventricular and abdominal limbs can be tested in sequence from this
location after they have been disconnected from the valve. Non-functioning ventricular
catheters that are adherent can be removed by gentle traction under most circumstances,
but we do not advocate more aggressive measures: rather, a new shunt should
be placed at an alternative site.
Passage of a new peritoneal shunt down an established fibrous tract is occasionally
possible as long as shunt infection has been ruled out preoperatively. Routine
CSF culture in the absence of infectious signs or symptoms is not recommended
as positive cultures in this setting are not predictive of subsequent infection.(12)
7.2. Infectious Shunt Failure
Shunt infection is widely believed to be caused by contamination at the time
of surgery, with occasional infections caused by later wound breakdown either
due to CSF fistulization or skin breakdown over hardware.(2)
Most shunt infections usually present within 3 months of shunt insertion, and
almost all within 6 months. The rate of shunt infection in North America is
approximately 8-10% (13) with some series reporting less than
1% (14), but in Africa is likely higher.(15)
The most common organisms grown are consistently S. epidermidis (~40%), followed
by S. aureus (~20%).(16)
Risk factors for shunt infection include prematurity, (17,18)
elaborate shunt configurations, multiple separate shunts, previous shunt infection,
surgical inexperience, myelomeningocele, post-operative CSF leak, and longer
duration of surgery.(19)
Common techniques to avoid shunt infection include the use of generous skin
preparation, meticulous and consistent surgical technique, and preoperative
prophylactic antibiotics.(20) Although there is significant
world-wide heterogeneity with regards to choice of antibiotic (21),
we recommend ceftriaxone or cefazolin upon induction of anaesthesia. A Cochrane
review in 2006 has supported the use of antibiotic prophylaxis in reducing shunt
infection, with no evidence of benefit beyond 24 hours.(22)
As advocated by Faillace et al., the avoidance of shunt-to-skin contact resulted
in a three-fold decrease in shunt infection rates from 9.1 to 2.9%.(23)
As mentioned earlier, valve design does not appear to have any effect on shunt
infection. The surgeon should develop a consistent routine using the same equipment,
and a meticulous approach: some authors have reported very low infection rates
using similar techniques.(24) Finally, shunts should not be
relegated to the most inexperienced member of the team. We agree with the author
who suggested: “Although less glamorous than other neurosurgical cases,
shunting procedures deserve no less attention to detail.” (25)
Because conventional antimicrobial techniques are not effective in treating
the bacterial biofilms that affect most neurosurgical-related device infections,
all infected shunts should be removed.(26) This is combined
with the insertion of an external ventricular drain with ongoing systemic and
optional intrathecal antibiotics, with replacement of the shunt 10-14 days later
with preoperative confirmation of a sterile CSF. Treatment with antibiotics
alone has a high failure rate, and is probably only relevant in the high-risk
surgical patient. Vancomycin has poor CSF penetration by IV route, and thus
preservative-free ventricular vancomycin has been commonly used to treat shunt
infections despite the incomplete understanding of side effects and toxicity.(27)
7.3. Shuntalgia Syndrome
This unusual shunt complication presents with focal discomfort around the shunt
site without swelling, fluctuance or redness. There may be tenderness along
the shunt itself, and there is usually a hard fibrotic sheath of scar tissue
around the shunt. It is common in adolescents, and should generally be treated
with conservative measures although narcotic analgesics have been required in
some cases.(2)
7.4. Shunt Separation / Fracture / Migration
Although this occasionally occurs within the first few months of surgery it
is thankfully rare. Clinical examination and if necessary a shunt series of
plain radiographs along the entire shunt tract is sufficient to confirm the
diagnosis. The phenomenon of arrested hydrocephalus (whereby a child develops
true shunt independence) is rare: 80% of children who have stable ventricles
despite a disconnected shunt have a raised ICP.(28) Therefore
most non-functioning shunts should be revised.
7.5. Hollow Viscus Perforation
Perforation of virtually every hollow viscus by the peritoneal catheter has
been described, but is usually diagnosed by observation of the catheter protruding
from the anus. The risk of hollow viscus perforation has been estimated at 1/1000
shunt years. (29) Remarkably, peritonitis is rarely a presenting
feature, likely due to the gradual erosion of the shunt through bowel. Treatment
is similar to other cases of shunt infection and involves removal of the shunt
in its entirety via a single valve-site incision in the cranium, external drainage
for 10-14 days with intrathecal or IV antibiotics followed by shunt replacement.
Laparotomy is reserved for the rare case of peritonitis, but is not routinely
required to remove the shunt.
8. Prognosis and Outcomes
The mortality associated with shunt placement is about 0.1%, but shunt failure
is more lethal at 1-4% - especially in the African setting with its frequent
difficult and delayed access to health care. The operative risk of ETV is still
being defined, but perioperative mortality may approach 1%.(2)
Shunts fail due to mechanical or infectious causes at a rate of 30-40% within
the first year after placement,(13) 15% within the 2nd year,
and 1-7% per year thereafter.(2) Shunt infection is associated
with reduced IQ and school performance, and a higher risk of future shunt infection.(30)
Although the risk of ventriculitis is reduced after ETV, it is not zero.
9. Prevention
In East Africa, the single most common cause of hydrocephalus is infection of
the CNS, usually via neonatal meningitis or ventriculitis. Neonatal sepsis is
common and is exacerbated by the lack of skilled perinatal care for the majority
of births in Africa. Newborns presenting with febrile illness should ideally
receive appropriate diagnostic tests and directed antibiotic therapy, and not
just empiric therapy for presumed malaria. Efforts at improving perinatal care
in developing countries will undoubtedly help to reduce the incidence of post-infectious
hydrocephalus. The association of neural tube defects with hydrocephalus also
mandates their prevention. There is excellent evidence to counsel for the use
of 0.4 mg of folic acid daily in all women of child-bearing age, and 4 mg daily
for mothers with previous children born with neural tube defects as a means
of prevention.(31) The fortification of wheat flour with folate
has met with success in many developed countries (32,33)
and there is increasing advocacy for it in the developing world.(34,35)
10. Ethical Issues
There is a paucity of literature concerning the ethics of non-treatment of hydrocephalus,
and issues surrounding resource allocation in the treatment of this disease.
Informed consent of the patient and family should address the need for life-long
ongoing surveillance of any child treated for hydrocephalus, the risk of shunt
infection, shunt failure, and death. Families should be educated regarding signs
of infection or shunt failure at the first admission.
Although we are not aware of any guidelines regarding assessment of medical
futility in the setting of hydrocephalus, we recommend extreme caution in shunting
children with head circumferences > 60cm, or in patients who have non-healing
pressure sores on the cranium. For many of these children, aggressive surgical
intervention is futile, and family resources are challenged by lengthy or repeated
admissions.
Lastly, because of the higher incidence of hydrocephalus in developing nations,
it is likely that research efforts will continue to be directed in this area.
As in any research setting, attention to a meticulous informed consent process
is required, particularly for those who are more vulnerable because of poverty
or lower education.
11. Recommendations
1. Early treatment of hydrocephalus with ventriculo-peritoneal shunts remains
the best method of preventing life-long disability from increased intracranial
pressure in Africa.
2. Clinical symptoms and signs and cranial ultrasound are sufficient for the
diagnosis and management of children with hydrocephalus.
3. Simple valved shunts such as the Chhabra shunt are as effective as more sophisticated
devices and save significant resources.
4. Shunt placement must be a thoroughly sterile procedure performed by skilled,
experienced surgeons.
5. Both mechanical and infectious shunt complications can be significantly reduced
through meticulous technique and experience.
6. Children shunted for hydrocephalus must be followed up for life and have
rapid access to health care facilities in the case of complications.
7. Endoscopic third ventriculostomy shows significant promise for avoiding shunt
morbidity in children with hydrocephalus, but remains limited by technology
and skill.
8. Besides early diagnosis, prevention of hydrocephalus can be accomplished
through efforts directed at the correct management of neonatal infections and
folic acid supplementation for all women of child-bearing age.
Nicholaus Bauman MD
Senior surgical resident
McMaster University Faculty of Medicine
Hamilton, ON, Canada
Dan Poenaru MD, MHPE, FRCSC, FACS, FICS, FCS-ECSA
Adjunct Professor of Surgery and Paediatrics, Queens’ University, Kingston,
Canada
Hon. Professor of Surgery, Aga Khan University, Nairobi, Kenya
Medical Education & Research Director, AIC Kijabe Hospital
Kijabe, Kenya
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