INTERNATIONAL FEDERATION FOR HYDROCEPHALUS AND SPINA BIFIDA

Consultative status special category with Economic and Social Council of the United Nations

Consultative status, Council of Europe

ENDOSCOPIC THIRD VENTRICULOSTOMY:

Initial Experience at CURE Children's Hospital of Uganda

Benjamin C. Warf, M.D.

Lynda MacGowen, R.N.

Hydrocephalus is the abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain which results when the rate of CSF production is not matched by the rate of CSF outflow and subsequent absorption. This may result from: 1) obstruction to CSF flow out of the ventricles; 2) obstruction to CSF flow within the subarachnoid spaces around the brain; or, 3) inadequate CSF absorption from the subarachnoid spaces into the bloodstream. Causes of hydrocephalus include: congenital abnormality; infection (e.g. meningitis); intracranial hemorrhage; and brain tumor. The most common cause of hydrocephalus in our patient population is infection (over 60%).

The most common treatment for hydrocephalus is placement of a ventriculoperitoneal shunt (VP shunt). An alternative treatment is endoscopic third ventriculostomy (ETV). Shunts are accompanied by a number of problems. They are prone to infection, especially within the first 3 months after operation. Shunt infections are life threatening and expensive and time-consuming to treat. VP shunts are also prone to malfunction. One recent large prospective multi-institutional study found that 40% of patients required a shunt revision within 2 years of initial shunt placement. Given a lifetime of shunt dependency, these problems are especially dangerous when access to competent care is difficult.

An alternative treatment is endoscopic third ventriculostomy (ETV). This treatment is minimally invasive. It also avoids infection, shunt dependency, the potential for shunt malfunction, and the cost of a shunt. ETV makes a hole in the floor of the third ventricle, which allows CSF to escape from the ventricles into the subarachnoid spaces, from which it is subsequently absorbed. If the hydrocephalus is caused by an obstruction to CSF flow within the ventricles, obstruction to the normal CSF outflow from openings in the IVth ventricle, or obstruction to CSF flow within the basal subarachnoid spaces around the IVth ventricle, the ETV will bypass any of these obstructions and relieve the problem if the normal CSF absorptive mechanisms are functioning adequately.

This presentation reviews our preliminary experience with ventriculoscopy for attempted ETV in our first 63 patients between June 18 and September 7, 2001. Because our patient population is dominated by infants and by post infectious hydrocephalus, we were particularly interested in the efficacy of ETV among these groups, since these have historically been considered less favorable for ETV.

The necessary equipment for this operation includes an endoscope, a video camera and monitor, a fiberoptic light source, and a cautery device for use through the endoscope. The procedure begins with a small incision in the scalp followed by a small opening in the lining of the brain (dura). The cortical surface is cauterized and the scope is inserted after making a path with an introducer. The intraventricular anatomy is identified and a 4-6mm hole is made in the floor of the third ventricle if it is deemed safe to do so. This allows CSF to escape into the subarachnoid spaces beneath. The scope is then removed and the dura and scalp are closed.

Prior to surgery patients undergo cranial ultrasound imaging. Patients excluded from ETV in this group, were newborns with hydrocephalus in association with myelomeningocele and patients with prohibitive anatomic abnormalities or distortion. Patients are discharged at 2 or 3 days postoperatively and reviewed at 7-10 days, 1 month, 3 months, 6 months, and 12 months postoperatively. Parameters for success are similar to those for shunting: decompressed fontanelle, arrest or decrease in head circumference, improved signs and symptoms.

Of 64 attempted ETV’s, 43 were completed and subsequently successful in treating the hydrocephalus (54%). 21 attempted ETV’s were abandoned (31%). 10 patients (15%) had a completed ETV but required shunting later on. Among post-infectious hydrocephalus (PIHC) patients, 45 had attempted ETV with 29 (64%) being completed and 16 abandoned. Among non-post infectious hydrocephalus (NPIHC) patients, 20 had attempted ETV with 15 (75%) being completed and 5 abandoned. Reasons for abandoning the ETV attempt included poor visibility because of turbid CSF (2 NPIHC/4 PIHC); thick, scarred IIIrd ventricle floor (0 NPIHC/3 PIHC); close basilar artery (3 NPIHC/2 PIHC); and distorted anatomy (1 NPIHC/5 PIHC).

88% of patients undergoing ETV were 2 years or younger, 72% 1 year or younger, and 45% 6 months or younger. Overall, infants less than one year of age were more likely to have an ETV attempt abandoned (37%) then children older than one year (22%).

Obstruction of the aqueduct (a narrow passage for CSF flow within the brain) is a cause of hydrocephalus for which ETV is likely to be successful. Among completed ETV’s, the majority of the PIHC group had a small IVth ventricle on ultrasound and an obstructed aqueduct noted at endoscopy, while the NPIHC group were equally divided with half having a normal or large IVth and an open aqueduct noted at endoscopy.

41 patients underwent a completed ETV. Follow up thus far is from 1 to 3 months. Failures have undergone VP shunt placement. Two patients underwent repeat ETV when prior ETV was found closed on repeat endoscopy.

10 of 41 patients (24%) have required shunting. This includes 21% of PIHC patients and 33% of NPIHC patients. There were an equal number of failures with evidence of open and obstructed aqueducts (5 each).

Potential prognostic parameters for ETV success include age of patient, cause of hydrocephalus (PIHC vs NPIHC), and the size of the IVth ventricle (indicative of the status of the aqueduct). Failure rates according to the latter two parameters were as follows: PIHC/small IVth – 22%; PIHC/large IVth – 29%; NPIHC/small IVth – 17%; NPIHC/large IVth – 43%. Therefore, the latter group appears to be a group that stands out as having a poorer prognosis for ETV success, and this likely includes those patients with communicating hydrocephalus in whom abnormal CSF absorption may be a factor.

Failure rates by age are as follows: 2-3 months – 20%; 4-6 months – 36%; 7-12 months – 33%; 13-24 months – 25%; >24 months – 0%. The overall success rates were: 68% for children 6 months and younger; 68% for children 1 year and younger; 75% for children 1-2 years of age; no known failures for children 2-21 years. The overall success rate for the entire group was 76%.

There were no serious complications of ETV. 2 patients had CSF leaks, which were resolved. There were no infections.

Conclusions: 1) ETV can be performed safely in this setting. 2) Overall success rate was around 75%. 3) Results were slightly less successful in young infants, but age is not a contraindication. 4) ETV works well for post infectious hydrocephalus (79% success rate). 5) The group with the single highest failure rate was that of patients with non-post infectious hydrocephalus and a large IVth ventricle. 6) ETV should be the first-line therapy for hydrocephalus in the developing world.