Shunt Systems

CSF shunts have been performed for decades and still represent the most important advance made until now in the treatment of hydrocephalus when endoscopic treatment is not indicated or possible.

A CSF shunt involves establishing an accessory pathway for the movement of CSF in order to bypass an obstruction of the natural pathways.

The shunt is positioned to enable the CSF to be drained from the cerebral ventricles or sub-arachnoid spaces into another absorption site, the right atrium of the heart or the peritoneal cavity, through a system of small tubes known as catheters. A regulatory device (known as a valve) which may be more or less sophisticated, may be inserted into the pathway of the catheters. This drainage enables the excess CSF within the brain to be evacuated and, thereby, the pressure within the cranium to be reduced.

 

The entire shunt system is positioned under the skin.

In obstructive hydrocephalus, the end of one of the catheters must imperatively be placed within the ventricular system and is known as the ventricular or proximal catheter.

In non-obstructive hydrocephalus, the proximal catheter is placed either in the ventricles (ventricular catheter) or in the sub-arachnoid space, at the level of the lumbar spinal column (lumbar catheter).

 The catheter, one of the ends of which is placed in the peritoneal cavity or in the right atrium, is called the distal catheter

 Ventriculo-Peritoneal Shunt (V-P)

The CSF is shunted from the cerebral ventricles to the peritoneal cavity where it is reabsorbed into the blood through the peritoneum, the membrane which lines the gastro-intestinal organs. 


 Ventriculo-Atrial Shunt (V-A)

The CSF is shunted from the cerebral ventricles into the right atrium of the heart. The CSF is then shunted directly into the blood circulation.


 Shunt system implantation

Make abdominal incision

Make cranial incision

Guide peritoneal catheter passer

Tunnellise peritoneal catheter

Position ventricular catheter (Burr Hole & insert)

Connect ventricular catheter to valve & position the valve

Check the flow at the end1of peritoneal catheter

Trim and position peritoneal drain

Close cranial incision

Close peritoneal incision

Shunt complications

Examples of possible complications include shunt malfunction, shunt failure, and shunt infection. Although a shunt generally works well, it may stop working if it disconnects, becomes blocked (clogged), infected, or it is outgrown. If this happens the cerebrospinal fluid will begin to accumulate again and a number of physical symptoms will develop (headaches, nausea, vomiting, photophobia/light sensitivity), some extremely serious, like seizures. The shunt failure rate is also relatively high (of the 40,000 surgeries performed annually to treat hydrocephalus, only 30% are a patient's first surgery) [9] and it is not uncommon for patients to have multiple shunt revisions within their lifetime.

The diagnosis of cerebrospinal fluid buildup is complex and requires specialist expertise.

Another complication can occur when CSF drains more rapidly than it is produced by the choroid plexus, causing symptoms -listlessness, severe headaches, irritability, light sensitivity, auditory hyperesthesia (sound sensitivity), nausea, vomiting, dizziness, vertigo, migraines, seizures, a change in personality, weakness in the arms or legs, strabismus, and double vision - to appear when the patient is vertical. If the patient lies down, the symptoms usually vanish in a short amount of time. A CT scan may or may not show any change in ventricle size, particularly if the patient has a history of slit-like ventricles. Difficulty in diagnosing overdrainage can make treatment of this complication particularly frustrating for patients and their families.

Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure. Diagnosis of the particular complication usually depends on when the symptoms appear - that is, whether symptoms occur when the patient is upright or in a prone position, with the head at roughly the same level as the feet.

PROGRAMMABLE SHUNTS 

 Shunt complications

Examples of possible complications include shunt malfunction, shunt failure, and shunt infection. Although a shunt generally works well, it may stop working if it disconnects, becomes blocked (clogged), infected, or it is outgrown. If this happens the cerebrospinal fluid will begin to accumulate again and a number of physical symptoms will develop (headaches, nausea, vomiting, photophobia/light sensitivity), some extremely serious, like seizures. The shunt failure rate is also relatively high (of the 40,000 surgeries performed annually to treat hydrocephalus, only 30% are a patient's first surgery) [9] and it is not uncommon for patients to have multiple shunt revisions within their lifetime.

The diagnosis of cerebrospinal fluid buildup is complex and requires specialist expertise.

Another complication can occur when CSF drains more rapidly than it is produced by the choroid plexus, causing symptoms -listlessness, severe headaches, irritability, light sensitivity, auditory hyperesthesia (sound sensitivity), nausea, vomiting, dizziness, vertigo, migraines, seizures, a change in personality, weakness in the arms or legs, strabismus, and double vision - to appear when the patient is vertical. If the patient lies down, the symptoms usually vanish in a short amount of time. A CT scan may or may not show any change in ventricle size, particularly if the patient has a history of slit-like ventricles. Difficulty in diagnosing overdrainage can make treatment of this complication particularly frustrating for patients and their families.

Resistance to traditional analgesic pharmacological therapy may also be a sign of shunt overdrainage or failure. Diagnosis of the particular complication usually depends on when the symptoms appear - that is, whether symptoms occur when the patient is upright or in a prone position, with the head at roughly the same level as the feet.

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