According to the data derived from the studies that reported complications in the use of the LP shunt, 40 % of all complications reported are due to mechanical failure of the shunt [1, 7, 12, 14, 15, 19, 24, 26, 29, 32–35, 37, 40, 53, 54, 56, 62, 65, 73, 78, 80]. This complication typically presents with recurrence of preoperative clinical symptoms. It can be due to shunting obstruction (either along catheters or inside the valve), catheter migration, catheter disconnection or catheter fracture and catheter malposition. LP shunt obstruction is an insufficient CSF flow diversion inadequate to compensate the intracranial hypertension. Unfortunately, shunt obstruction, although suspected, is usually confirmed only after surgical revision. Obstruction can occur in any location of the shunt system, including the lumbar catheter, the valve, or the distal catheter. Surgical management is required and during the procedure each element of the shunt system should be individually tested for malfunction.

Disconnection or catheter fracture often has a subtle clinical presentation [1, 12, 32, 56, 81]. Many disconnections or fractures are found incidentally during follow-up routine visits or during radiological studies required for other purposes. However, catheter disconnection typically occurs shortly after surgical shunt placement. The most useful and sensitive imaging studies to demonstrate disconnection of catheter fracture are the shunt series. This complication requires surgical management, either urgent or elective depending on the clinical status of the patient. Both disconnection and shunt fracture are progressively decreasing its rates as the catheter materials improve with time. Similarly, catheter migration happens when an appropriately placed catheter moves from its intraperitoneal location to an extraperitoneal position where CSF no longer drains or the drainage is severely compromised. This complication is managed by repositioning the migrated catheter. Anticipation of possible problems from tethering should be addressed at the time of the initial shunt placement [1, 7, 12, 18, 19, 21, 23, 24, 26, 32, 33, 35, 49, 50, 53, 60, 65, 78, 80, 82–86]. Unfortunately, the avoidable surgical catheter malposition happens and when this occurs management is identical to catheter migration cases [38].

CSF overdrainage causes intracranial hypotension. It usually presents with intense headache which typically resolves when patients switch from vertical to horizontal position. Secondary intracranial hypotension has been reported as the number one complication in some studies [15]. The apparent decline in those rates when looking into the literature review may be due to a better prevention and avoidance by a more appropriate valve system selection [7, 18, 19, 21, 23, 25, 27, 29, 32, 33, 35, 37, 38, 40, 49, 69, 73, 78, 87]. Treatment of overdrainage requires surgical valve replacement with a valve with more resistance or adding an antisiphon device to the shunting system.

Chronic overdrainage may lead to a secondary tonsillar herniation or acquired Chiari Malformation type I, and sometimes even requiring decompressive posterior fossa craniectomy [7, 22, 24, 26–28, 47, 54, 60, 73, 88–90]. A vigilant postoperative follow-up policy may reduce the rate of post-LP shunt tonsilar herniation by increasing the rates of LP shunt revision in patients with symptoms of overdrainage post-LP shunt sparing decompressive posterior fossa craniectomies.

Significant CSF overdrainage may result in the formation of subdural collections due to the collapse of the brain and accumulation of fluid or blood around the brain [19, 21–23, 26, 29, 30, 32, 41, 53, 76, 91, 92]. Most commonly, benign cerebrospinal fluid collections are observed, however, subdural hematomas are possible. This complication has been reported mainly associated to NPH. It is exceptional in IIH [40, 76]. Three approaches could be proposed for extra-axial fluid collections. First, it may be possible to manage these collections conservatively if they are small and do not cause brain compression or herniation. A second option is to treat the overdrainage by replacing the valve with one with more resistance or inserting an antisiphon device. The third option is to drain the extra-axial fluid collection either alone or in combination with changing the valve. Drainage may be accomplished by a burr hole and a temporary drain or via a subdural catheter that is spliced into the existing shunt system below the valve. This complication is best prevented by avoidance of overdrainage.

This spinal group of complications includes spinal scoliosis, lumbar lordosis, or the combination of both of them. We believe that spinal deformity complications may be overrepresented in comparing it to the rest of LP shunt complications. During our review we found a lack of uniformity reporting spinal deformity complications. In some of the manuscripts reviewed, all of the spinal deformity complications were reported as a group, while others reported each spinal deformity complication independently [20, 24]. This complication is intrinsically related to patients in their infancy through adolescence, when many developmental changes occur in a small amount of time, and it is highly associated with patients that already have syringomyelia. Syringomyelia may be responsible for the spinal deformity and spasticity of the posterior spinal muscles may be a cause of hyperlordosis.

Infection rates reported include meningitis, discitis, and peritonitis [1, 7, 19, 21–27, 29, 32, 33, 35–40, 49, 56, 60, 73, 78]. It is surprising that the sum of these three complications is much lower than similarly reported in other type of shunting systems. The difference in infection rates between different shunting systems is not well known and difficult to assess.

Post-LP shunt back pain and radiculopathy have been underestimated and underreported [1, 7, 19, 21, 22, 24–26, 38, 41, 49, 69]. Radiculopathy leads to significant patient limitation in quality of life and work performance. This is due to direct spinal root irritation by the lumbar catheter. The treatment for this complication is surgical revision with repositioning of the lumbar catheter.

CSF leak is one of the most feared complications due to the fact that once CSF leak develops it is difficult to fix [1, 23, 25–27, 56, 65, 71, 87, 93]. When CSF leak happens, it is advisable to completely remove the shunting system, possibly insert an external CSF drainage at a different location and wait until the patient has healed before further surgical treatment. The presence of infection will delay the insertion of a new system usually until after the completion of an appropriate course of antibiotic treatment and until confirmation of CSF sterility a few days after antibiotic discontinuation. Sometimes the CSF leakage persists and direct repair of the durotomy becomes necessary.

Each of the following complications represents less than 1 % and together total 6 % of all complications reported in the literature. They are pneumocephalus [22, 23, 38, 94], seizure [29, 95], subarachnoid hemorrhage [96], venous sinus thrombosis [96], pseudomeningocele [33, 35, 44, 97], wound dehiscence [1, 23, 26, 29], syringomyelia [28, 98], myelopathy [22], hydrocele [1, 99], abdominal pain [23, 25, 49, 73], abdominal hemorrhage [100], and gastrointestinal perforation [36].