In our series of 271 patients (198 infants and 73 adults) with non tumoural hydrocephalus treated between 1986-96, 256 patients, were operated upon (332 procedures) using ventriculoperitoneal shunt in 235 cases (70%), ventriculoatrial shunt in 76 cases (23%), plexectomy in 9 cases, lumboperitoneal shunt in 3 cases and stereotactic ventriculostomy in 2 cases. We have experienced the following complications in the series treated by shunts (244 cases): 6 children died in the post-operative period (3%) and 2 adults (2%); 29 cases of post-operative meningitis (9%). Sixty-five patients (20%) had a shunt revision because of the mechanical complications.

Among 248 surviving patients, we have a follow-up of 195, 110 patients have good evolution (56%), 35 have a moderate retardation (17%), 35 have a severe retardation (17%) and 2. 15 are blind (11%).(p14-22)

Keywords: Hydrocephalus, Shunts Complication, Surgical Management

INTRODUCTION

Hydrocephalus is associated with the ventricular enlargement and the increase of the Cerebrospinal Fluid (CSF) pressure inside the ventricles. Hydrocephalus is due to a basic physiological CSF disorder. The different causes of this disorder result more often from a reduced capacity of the CSF resorption, which in turn, leads to its accumulation inside the ventricles.

The treatment of hydrocephalus is mainly shunting the CSF from the ventricles a resorption site: it could be its natural resorption site obtained by by-passing the obstruction (internal shunts); extra-cranial resorption site or an external shunt. Although surgical treatment of hydrocephalus started more than a hundred years ago, the ideal technique for treatment is not yet available and hydrocephalus remains a neurosurgical condition which is frequently associated with complications and surgical reinterventions.:

Historical review of the surgical treatment of hydrocephalus:
The surgical techniques used in the management of hydrocephalus since the beginning of the century could be divided into three groups:

	1.	Procedures designed to reduce CSF production using choroid plexus excision or cauterisation; these two techniques were eventually abandoned because of the equivocal results and an unacceptable mortality. (5,38,40,41)
	2.	Procedures designed to by-pass obstructions of CSF flow and to allow it to circulate physiologically. Three techniques are common in this group and involve variety of approaches: Third ventriculostomy, introduced by DANDY (1922), used by many others later on remains today, after the introduction of endoscopic instrumentation and stereotactic procedures, an excellent operation in selected cases of obstructive hydrocephalus. 8,16,17,22 The two other techniques in this group are represented by the ventriculcisternostomyintroduced by TORKILDSEN in 1939 (43) and the cannulation of the aqueduct introduced by DANDY in 1920 and continued recently by LAPRAS. These two techniques are rarely used because of the poor result in the first one, especially in infants and high mortality in the second. (9,24,28)
	3.	Intracranial-Extracranial CSF shunt represent the third group of surgical techniques which was widely developed by many surgeons around the turn of the century. Since the surgical treatment of hydrocephalus started, numerous procedures were attempted, all shunting CSF from the ventricles or subarachnoid space to different structures in the body:
		Head and neck structures: shunting of the CSF from the lateral ventricle to the subgaleal region, or the intracranial veins and sinuses, to the scalp and neck veins (internal jugular vein), to the mastoid atrium. (14,15,19,30,31)
		Spinal structures: spinal epidural space, vertebral bone. (12,45,48)
		Thoracic structures: plural cavity and right atrium. (35,36,37)
		Abdominal structures: peritoneum, omental bursa, stomach, gall bladder, ileum, ureter and fallopian tube.(1,3,6,13,20,25,27,29,32,47)

Today, the surgical treatment of hydrocephalus is based on four techniques: Endoscopic fenestration of the floor of the third ventricle (endoscopic third ventriculostomy), ventriculoperitoneal shunt; ventriculojugular shunt and lumboperitoneal shunt.

The last three techniques need an implantation of foreign material (valves and catheters) with the necessity for constant vigilance to prevent and to treat the two most frequent complications of these techniques: infection and malfunction.

Valves system and shunt selection: Atypical shunt system includes four components: a ventricular catheter, a reservoir, a valve and a distal catheter.(44) All these components exist in different sizes and are joined to each other; to be adapted to the age and size of the patient. The mechanics of the classical valve is based on differential pressure with different opening pressure, high, medium and lower pressure (Holter valves, Hakim valves, PS Medical valves, Schulte Heyer valves and others from different manufacturers). All these valves are working by opening and allowing CSF flow when the differential pressure between the valve inlet and outlet exceeds a certain set point for that valve. So the CSF flow depends on the differential pressure and the resistance of the shunt system components. New valves were designed with an antisiphon device or flow control to prevent an overshunting (Orbis-sigma valve from Cordis, Delta valve from PS Medical and Codman-Medos valve).(39,46) The valve can be a slit valve (Holter), spring-ball valve (Hakim) or diaphragm-rubber valve (PS Medical and Heyer-Shunt).

Many parameters influence neurosurgeons in the choice of shunt system: of course their experience and training, but also the type of hydrocephalus, age of the patient, advertising of the manufacturers, style use and comfort of the neurosurgeon and cost; this last parameter is very important in developing countries. Before making any choice neurosurgeons should be familiar with the different categories of shunt systems proposed by different manufacturers and should have a personal experience in shunt implantation. We should understand that the ideal shunt is not yet invented and that the most sophisticated shunting device is not always the best one.


Shunt insertion technique: Prevention and reduction of shunt complications depends mostly on the surgical technique used to insert the shunt. The following guidelines should be respected:

		A shunt implantation should be considered as a major operation, performed by a senior neurosurgeon experienced in shunt insertion.
		A choice of shunt system should be based on patient age, aetiology of hydrocephalus, availability (cost) and experience of the neurosurgeon with the material.
		A maximum vigilance should be dedicated to prevent shunt infection: procedure carried out early in the morning at the beginning of the surgical schedule; surgical team reduced in the operating room; strict pre-operative protocol respected by the surgeon; nurses and anaesthetists in terms of patient preparation, material touching, surgical technique and time duration.
		Surgical technique should respect the standard sequences of the procedure (abdominal time, subcutaneous time and cranial time), avoid malpositioning and wrong length of the ventricular catheter (the main cause of proximal obstruction) and avoid the use of connectors and sutures (the most common site of fracture and disconnection of the distal catheter).

Complication of shunt operations: The complication of shunt system could be divided into three groups: infection, mechanical malfunction and complications due to incongruous drainage.

		The infection rate varies in the literature between 1-10% depending on the many factors we have mentioned above. A majority of the factors involved in shunt infection are related to the surgical technique and pre-operative environment of the patient, which make prevention possible and reduced to less than 2%. 2 The risk after shunt infection is high (20-30%) and the shunt must usually be removed and reimplanted after having brought infection under control.
		Mechanical complications are related to the surgical technique and design of the shunt system.4,26 The long list of these complications makes it difficult to classify themes; the frequent are: rupture and disconnection with or without slipping and migration of the system, obstruction, shortening or kinking of the distal catheter, visceral damage or perforation, surgical displacement.

These mechanical complications occur in 20-35% of patients and all require a shunt revision. Considering the large series in the literature mechanical complications mostly affect the distal catheter, followed by a ventricular catheter and a valve.

Complications secondary to shunt drainage are theoretically related to the hydrocephalus proprieties of the shunt, but in fact could also be related to surgical technique. The differential pressure mechanism which regulates the flow rate of the CSF face many physiological variations: ventricular pressure variations, peritoneal space and the gravity force variations. The non adaptation of shunt device to the physiological variations of the patient, in terms of pressure and shunt resistance, lead to incongruous drainage which results in underdrainage or overdrainage. The latter is more common and felt to cause slit ventricle syndrome, craniostenosis, subdural haematoma, occlusion of the aqueduct of Sylvius, and orthostatic headaches .(7,10,11,21,23)

Surgical treatment and results in our series:

		Clinical material: 271 patients with non tumoural hydrocephalus were treated in our department in the last ten years (1986-96). 156 (57.5%) were male and 115 female (42.5%). The age distribution shows that 116 infants were under 2 years (42%), 82 (30%) between 2 and 15 years and 73 (28%) over 16 years (Table 1). Intracranial hypertension (ICH) was the most frequent clinical symptom with cranial vault enlargement, decreased visual acuity and mental retardation (Table 2 and 3). The aetiologies were dominated by congenital malformations and meningitis (Table 4).
		Surgical treatment: No surgical treatment in 15 patients for different reasons: clinical stabilisation (10 cases), bad clinical conditions with pre-operative death (4 cases) and non availability of material (2 cases). Two hundred and fifty-six patients were operated on (332 procedures) using the following techniques: ventriculoperitoneal shunt in 235 cases (70%), ventriculoatrial shunt in 76 cases (23%), plexectomy in 9 cases, lumboperitoneal shunt in 3 cases and stereotactic ventriculostomy in 2 cases (Table 5 and 6). In our series, we unfortunately had to use the type of shunt available in the hospital or the one the patient's families could afford. Thus, in most cases, we used medium pressure shunts whose mechanism is based on differential pressure.
		Post-operative complications (Table 7): We had an unacceptable mortality rate with plexectomy (4 deaths) which made us abandon this technique. The three cases treated by stereotactic ventriculostomy had a successful result. We have experienced the following complications in the series treated by shunts (244 cases).
		Mortality: 6 children died in the post-operative period (3%) and 2 adults (2%) intraventricular haemorrhage in 3 cases, meningitis in 4 cases and subdural haematoma after an overshunting in 1 case.
		Infection: 29 cases of post-operative meningitis (9%); 9 died and 20 improved after shunt removal, external drainage and antibiotics. A second shunt was reinserted in a period of 3 weeks to 3 months. In addition to meningitis, we had a superficial skin infection in 7 cases, (abdominal wound in 4 cases and cranial wound in 3 cases).
		Mechanical complications: 65 patients (20%) had a shunt revision because of the mechanical malformation, one revision in 49 cases and 2 revisions in 16 cases. Among these mechanical complications, we had two cases of anal extrusion of the peritoneal catheter.

Table 1 - Age of patients with non-tumoural hydrocephalus in our series (271 cases) 0 – 2 years 2 – 16 years Over 16 years : : : 116 = 42% 82 = 30% 73 = 28%

Table 2 - Clinical Symptoms of non-tumoural hydrocephalus in children (198 cases)   -Cranial V. Enlargement -I.C.H. -Blindness -Retardation -Neurological deficit -Epilepsy : : : : : : 138 cases   90 cases   31 cases   91 cases   36 cases     2 cases

Table 3 - Clinical Symptoms of non-tumoural hydrocephalus in adult patients (73 cases).   I.C.H Neurological deficit Epilepsy ADAMS-Hakim’s Syndrome 63 cases 14 cases 11 cases 11 cases

Table 4 - Causes of non-tumoural hydrocephalus in our series (271 cases)

AETIOLOGY INFANTS ADULTS

Congenital malformations           Sylvius aqueduct stenosis           Dandy Walder malformation           M + M meningocella                CVJ malformation                Foramen of Monro agenesis                Arachnoid cyst      Infection and inflammation           T.B. Meningitis           Non-specific meningitis           Head Trauma      Unknown causes      Normal pressure hydrocephalus 104 (52%) 50 18 30 6 57 (29%) 16 37 4 37 (19%) 37 (50%) 26 8 1 2 17 (21%) 2 7 6 10 (14%) 11 (15%)

TOTAL 198 (100%) 73 (100%)

Table 5 - Types of shun used in non-tumoural hydrocephalus in infants (187 cases, 236 procedures)

V.P. Shunt    V.A. Shunt    L.P. Shunt    Stereot. Cisternotomy    Plexectomy : Initial Implantation 146 cases 28 cases 2 cases 2 cases 9 cases Reimplantation 40 Cases 9 Cases Total 186 = 80% 37 = 17%

Table 6 - Type of shunt used in non-tumoural hydrocephalus in adult patients (69 cases, 96 operations)

V.P. Shunt    V.A. Shunt    L.P. Shunt    Stereot. Cisternotomy Initial Implantation 36 cases 27 cases 4 cases 1 case Reimplantation 13 Cases 12 Cases 3 Cases Total 49 = 51 % 39 = 40 % 7 Cases

Long-term evolution: Among 248 surviving patients, we had a follow-up of 195(meantime evolution 3-1/2 years). One hundred and ten patients have good evolution with an acceptable mental and intellectual development (56%), 35 have a moderate retardation (17%), 35 have a severe retardation (17%) and 15 are blind (11%).

CONCLUSION

Non-tumoural hydrocephalus is our practice. It affects in the first place infants, children and then adults. Its clinical and radiological characteristics are easily identified in infants and children. As for adults, the diagnosis has to be based on further dynamic tests, especially the manometric test in one-third of the cases.

The traditional treatment of hydrocephalus consists of shunts; these unfortunately encounter many complications which can only be reduced by a strict surgical technique and an adequate choice of shunt material. The results are generally good and excellent in young patients if treated early. They are modest and even disappointing when the patient is old.

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