**Thanks**

2.38%, and the mortality rate was found 0.28%. Complications can be categorized as intraop-

Neurovascular injury and bradycardia are the most common intraoperative complications. Various authors reported arterial and venous bleeding during the procedure [59, 63, 70]. Considerable intraoperative bleeding is reported almost 3.7% of the procedures, and about 4.2% of the ETVs is abandoned due to hemorrhage. Many authors reported different rates of intraoperative bleeding. But severe bleeding rates are low as 0.6%, and the rate of the most frightening intraoperative complication of ETV—basilar artery rupture—is as low as 0.2%. Pseudoaneurysm formation in the basilar tip after basilar injury is reported. Bradycardia is reported up to 41% during ETV [71]. A proposed mechanism for bradycardia is the generation of Cushing reflex due to irrigation and stimulation of hypothalamic nuclei. Even cardiac

arrest is reported during an ETV performed for posthemorrhagic hydrocephalus [72].

Immediate preoperative complications include postoperative hemorrhagic complications like subdural hematoma, intraventricular hemorrhage, intracerebral hematoma, and epidural hematoma. The total rate of hemorrhagic complications is about 0.81%, and subdural hematoma being the most common hemorrhage [69]. A large corticotomy and sudden drainage of CSF are possible risk factors for development of subdural hematoma. Increased ICP of the subdural space also seems to be the cause of subdural hygromas. Central nervous system infections are one of the severe early postoperative complications. Meningitis or ventriculitis is recorded in 1.81% of the patients. Cerebrospinal fluid leak due to increased subdural pressure from corticotomy is also a postoperative concern as it can lead to CNS infections. Electrolyte and hormonal imbalances are reported in the literature. Systemic complications including syndrome of inappropriate antidiuretic hormone secretion, diabetes insipidus, and

The most important late complication is the failure of the ETV. Sudden deterioration and death are reported in the literature, but it occurs rarely [73, 74]. As the risk of epilepsy being very low for this procedure, seizures are still a possible complication developing after ETV. Neurological morbidity is a possibility although rare with a total rate of 1.44%. Memory deficits may occur after ETV, and suggested hypothesis is fornix injury during the procedure. Fornix contusion is reported in ETV patients up to 16.4% [33]. Memory problems can be transient as well as permanent. Other than neuropsychiatric problems, hemiparesis, decreased

Endoscopic third ventriculostomy is a novel treatment for noncommunicating hydrocephalus. Safety and efficiency of the procedure are proven. Indications of ETV are expanding day by day with good results reported for various diseases. Compared to CSF diversion techniques, ETV is preferable for select cases with avoidance of shunt dependency and thus shunt

consciousness, and gaze palsy are some of the rare neurological complications [69].

erative, early postoperative, and late postoperative.

120 Hydrocephalus: Water on the Brain

secondary amenorrhea are also found to be complications.

**7. Conclusion**

complications.

We wish to thank Cristina Brinza for her illustrations.
