Keywords: ventriculoperitoneal shunt - complications - reoperation - outcome
Palavras-chave: derivação ventriculoperitoneal - complicações - reoperação - desfecho
Hydrocephalus, pseudotumor cerebri and aracnoid cysts are the main causes of cerebral
hydrodynamics disturbance in adults. Surgical treatment is based on the implantation
of ventricular (peritoneum, atrium or pleural cavity) shunt system, neuroendoscopy,
or both[1 ],[2 ].
Shunt surgeries have changed the curve of hydrodynamics diseases treatment, especially
in infants. However, if they allowed treatment of several diseases, they have also
turned to be a problem themselves, resulting in many potential functional and infectious
complications[1 ],[2 ],[3 ],[4 ],[5 ].
Up to 80% of patients harboring a shunt may experience any kind of complications and
approximately 50% may need a revision or undergo a surgery complication during life.
Malfunction may be caused by infection or mechanical failure. Approximately 40% of
standard shunts malfunctions occur within the first year after the procedure and 5%
malfunction per year in subsequent years[4 ].
The objective of this study was to confirm safety and performance of Sphera® Duo when used in adult patients suffering from hydrocephalus, pseudotumor cerebri
or arachnoid cyst. We describe the clinical results and its application in a daily
neurosurgical practice.
METHODS
This is a retrospective, single-center, single-arm cohort study approved by the Hospital
das Clínicas da Faculdade de Medicina da Universidade de São Paulo Ethics Committee.
There was ethical adherence and the study was registered with the protocol CAPPESQ
0348/09. Data are generated with the review of 112 adult patient’s charts, who were
submitted to a VP shunt surgery for the treatment of hydrocephalus, pseudotumor cerebri
or arachnoid cyst, from June 2014 to December 2017, at Instituto de Psiquiatria do
Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. The SPHERA
DUO® (HPBio, Brazil) shunt was used in all cases. This study was carried out at the Hospital
das Clínicas, Universidade de São Paulo, São Paulo, Brazil.
SPHERA DUO® is a fixed pressure valve ([Figure 1 ]), which works through a sequential double coil spring mechanism, seat and ruby sphere.
According to the characteristic of the springs, three ranges of pressure difference
ensure a flow of 21 mL/h, which corresponds to physiological CSF production: low (3
to 7 cm H2O), medium (7 to 11 cm H2O), and high (11 to 14 cm H2O).
Figure 1 Sphera Duo Valve® , HpBio, São Paulo, Brazil.
Primary endpoints
Frequency and severity of complications or side effects occurring in one-year observation
period following implantation were recorded.
Secondary endpoints
Clinical improvement after one year of shunt implantation: resolution of the intracranial
hypertension syndrome (hydrocephalus, pseudotumor cerebri or arachnoid cyst) or improvement
of normal pressure hydrocephalus (NPH) triad (gait apraxia, memory alterations and
urinary incontinence).
Study population
Inclusion criteria
The patient has received a ventriculoperitoneal, ventriculoatrial or ventriculopleural
shunt, by implanting the SPHERA DUO® hydrocephalus shunt system.
Patient has been followed according to the institutional pre-established routine inpatient
and outpatient visits.
Age>16 years old.
Exclusion criteria
The patient received only the shunt (not the entire system - ventricular and peritoneal
catheter) to treat a diagnosed overdrainage in the previous implanted shunt of another
brand.
The patient was treated for ventriculitis with extraventricular drainage (EVD) shortly
before the implantation of the SPHERA DUO® hydrocephalus derivation system.
Surgical procedure
The standard VP shunt implantation technique applied in our service is composed of
cranial and abdominal approaches and is not different from the technique described
by Choux et al.[4 ] After initial approaches, we identify the peritoneum and perform the catheterization
of lateral ventricles. Simultaneously, we create a subcutaneous tunnel to allow the
passage of the distal catheter. The whole system is attached, and wounds are closed
with a tight suture.
RESULTS
Sample
In the period of three and a half years (from June 2014 to December 2017), 252 surgeries
were performed by the Group of Cerebral Hydrodynamics. Of these, 112 were included
in this study respecting the established criteria for structuring this cohort.
Fifty were male (45%) and 62 were female (55%). The youngest patient was aged 16 years
and the oldest, 90 years. The most commonly treated cerebral hydrodynamic disorder
was acquired hydrocephalus, accounting for 93 cases (83%) ([Figure 2 ]), and normal pressure hydrocephalus constitutes about 60% of this sample ([Figure 3 ]). Ninety-four valves were of medium pressure (84%), 13 of high pressure (11%) and
5 (5%) of low-pressure valves were implanted.
Figure 2 Types of cerebral hydrodynamics disturbance.
Figure 3 General clinical status at the 1-year after surgery follow-up.
Follow-up
Patients presented radiographic improvement detected with the reduction of the Evans
index, but less prominent in patients with NPH.
Overall, eighty-six patients (76%) presented clinical improvement of neurological
symptoms that led to the implantation of the shunt (triad of NPH or intracranial hypertension
in cases of hypertensive hydrocephalus, cerebral pseudotumor or arachnoid cyst), twelve
(11%) presented stability of symptoms and fourteen (13%) reported worsening of symptoms
([Figure 3 ]).
Seven patients were reoperated due to overdrainage (10%), with the replacement of
medium pressure valves by high pressure ones. Overdrainage was detected in neuroimaging
(tomography) examinations associated with headache and worsening of their neurological
condition (memory, gait or urinary incontinence). One patient was reoperated because
the distal catheter was outside the peritoneum in the abdominal subcutaneous tissue.
Four patients were reoperated due to an infection of the system; four patients were
reoperated due to abdominal wall cysts or herniations; one patient was reoperated
due to a malfunction of the shunt system ([Figure 4 ]).
Figure 4 Causes for reoperation.
In the 12-month follow-up period, there were no cases of wound dehiscence, superficial
infection or meningitis. There were no deaths related or not to surgery during the
follow-up period.
DISCUSSION
Shunt complications are an everlasting matter in shunt surgery. The intent of current
literature is to decrease complications and their consequences. The technology of
shunt, its materials and the surgical techniques may decrease mechanical and infectious
complications[1 ],[2 ],[3 ],[4 ],[5 ],[6 ],[7 ],[8 ],[9 ],[10 ],[11 ],[12 ],[13 ],[14 ],[15 ],[16 ],[17 ],[18 ],[19 ].
Shunt infection is a common complication, occurring in approximately 5 to 15% of procedures.
This may lead to ventriculitis, promote the development of loculated compartments
of cerebrospinal fluid (CSF), and may impair life quality of patients harboring shunts.
Mechanical shunt failure is another important cause of shunt failure. Like shunt infection,
it is most common during the first year after shunt placement. Shunt failures may
result from obstruction at the ventricular catheter, migration (partial or complete)
and excessive CSF drainage (overdrainage). Mechanical failure requires prompt recognition
and management[2 ],[8 ],[9 ],[10 ],[11 ].
Overdrainage is especially important in adults with non-hypertensive hydrocephalus
and can cause functional shunt failure, which causes subnormal ICP (particularly in
the upright position) and is associated with characteristic neurological symptoms,
such as postural headache and nausea. Overdrainage greatly reduces the size of ventricles,
causing the catheter to lie against the ependyma and choroid plexus, and these tissues
block the holes in the catheter[8 ],[9 ],[10 ],[11 ]. Overdrainage can lead to slit-ventricle syndrome, which is characterized by small
or slit-like ventricles, coupled with transient episodes of symptoms of raised ICP.
Changes in shunt, designed to address the problem of overdrainage, include valves
designed to open at different pressures and selected based upon the patient’s characteristics;
anti-siphoning devices to minimize the siphon effect caused by changes in posture;
and valves that regulate by flow rather than by pressure differences[13 ],[14 ],[15 ],[16 ],[17 ],[18 ],[19 ].
We had a rate of complications of 12.5%, mainly due to overdrainage and need for valve
replacement. The use of a programmable valve or anti-siphon system may mitigate such
complications.
One case in this study needed distal shunt revision because the distal catheter went
out from the peritoneal cavity to the subcutaneous space. After reoperation, patient
recovered the neurological status. This problem could be avoided with an appropriate
surgical technique. A thigh suture in reto abdominal muscle aponeurosis is indicated
for obese patients.
Our rate of symptom improvement was 76%, similar to that of other studies in literature[2 ],[3 ],[8 ]. This suggests the applicability and safety of the shunt.
In conclusion, Sphera Duo® shunt system is safe when used in adult patients suffering from hydrocephalus, pseudotumor
cerebri or arachnoid cyst. Seventy-six percent of the patients had their neurological
symptoms improved and the reoperation rate was 12.5% in the first year after surgery.