2 The procedure

2.1 Indications

2.1.1 This procedure is used to treat communicating hydrocephalus (normal pressure hydrocephalus) and benign intracranial hypertension (pseudotumour cerebri).

2.1.2 Communicating hydrocephalus is an uncommon condition caused by excess cerebrospinal fluid collecting in the subarachnoid space. Causes include congenital abnormality, brain haemorrhage and meningitis, but in some cases, no cause is found. The symptoms include confusion, gait disturbance and urinary incontinence. Untreated, the condition may cause brain damage or death.

2.1.3 Benign intracranial hypertension is an uncommon condition of unknown cause, in which the pressure of the cerebrospinal fluid is increased. The symptoms include headache, dizziness and visual problems. The prognosis is generally good, although a few people may experience permanent visual loss.

2.2 Outline of the procedure

2.2.1 A cerebrospinal fluid shunt is a system of valved tubes that carries cerebrospinal fluid from the subarachnoid space to another part of the body to drain it and prevent damage to the brain or eyes. Usually, a shunt is tunnelled under the skin, with the upper end in a cerebral ventricle and the lower end in the heart (ventriculo–atrial shunt) or in the peritoneum (ventriculo–peritoneal shunt). Alternatively, the upper end of the shunt may be placed in the subarachnoid space in the lumbar part of the back, with the lower end draining fluid into the peritoneum (lumbar–peritoneal shunt).

2.2.2 A lumbar subcutaneous shunt differs from the types of shunt described in section 2.2.1 in that the cerebrospinal fluid drains into the space immediately under the skin. A narrow tube is inserted percutaneously into the subarachnoid space in the lumbar part of the back and is tunnelled under the skin to a site where fluid can drain, usually in the flank or abdomen. The advantage is that general anaesthetic is not required, unlike for other shunt procedures.

2.3 Efficacy

2.3.1 No studies reporting efficacy outcomes of lumbar subcutaneous shunt were identified.

2.3.2 The Specialist Advisors noted that this procedure is only being undertaken by one surgeon in the UK. One Advisor was unsure about the efficacy of the procedure because the subcutaneous tissues do not absorb cerebrospinal fluid; however, data are being collected to investigate this.

2.4 Safety

2.4.1 No studies reporting safety outcomes of lumbar subcutaneous shunt were identified.

2.4.2 One Specialist Advisor considered the main potential adverse effects of the procedure to be infection, subdural haematoma and irritation of nerve roots.