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The trajectories of an external ventricular drain (EVD) can generally be categorized as either anterior or posterior. The entry points for anterior trajectories include the Kocher, Barrow, and Kaufmann points, whereas those for posterior trajectories include the Keen, Frazier, Sanchez, and Dandy points. These same trajectories apply intraoperatively, with the removal of cranial bone. Theoretically, any trajectory into the ventricular system can be used for an EVD. However, the neurosurgeon must account for the anatomy that will be transgressed. Placement of a lumbar drain usually requires the use of a Tuffier line at the L4-L5 intervertebral space.


This chapter covers the anatomy involved in the placement of external ventricular drains (EVDs) and lumbar drains (LDs). It is intended to provide a rationale for drain use and a reference on the two types of procedures for both the neurosurgeon and the medical care team.


Technically, any point on the scalp can be used as a straight-line entrance into the ventricles. The process is not this simple, though, because the brain that is transgressed is eloquent; therefore, the path with the least potential damage must be chosen. Several named points have historically been proven to be safe sites for access (Table 2.1). We invite the readers to review an excellent summary by Morone et al.1 of these named points.

TABLE 2.1Overview of External Ventricular Drain Access Points and Trajectories

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