Abstract
Lumbar drain placement is a procedure performed at the bedside or in the operating room to allow for controlled drainage of cerebrospinal fluid (CSF). This chapter will review the relevant anatomy, indications, contraindications, equipment, technique, complications, and suggestions for placement of lumbar drains.
4 Lumbar Drain
4.1 Introduction
A lumbar drain (LD) is a catheter that is inserted into the lumbar subarachnoid space to provide continuous access for cerebrospinal fluid (CSF) drainage. This is a sterile procedure that can be performed both at the bedside or in the operating room. Once the LD catheter is inserted into the thecal sac, it is then connected to a collection system which is used to collect CSF and monitor the output in a precise and controlled manner. A transducer can also be connected to the tubing to allow monitoring of intrathecal pressure, although the drain is not generally used for this purpose. In this chapter, we discuss the relevant anatomy, indications and contraindications, equipment, technique, troubleshooting if the drain malfunctions, and related complications.
4.2 Relevant Anatomy/Physiology
The choroid plexus, located throughout the intracranial ventricular system, produces the majority of CSF circulating within the central nervous system (CNS). At any point, there is approximately 125 to 150 mL of CSF circulating in adults with approximately 20% of the total CSF being located in the ventricles. The rest of the CSF is present in the subarachnoid cisterns. CSF flows from the lateral ventricles into the third ventricle via the foramen of Monro. From the third ventricle, CSF travels through the aqueduct of Sylvius into the fourth ventricle. It then exits the fourth ventricle medially through the foramen of Magendie, or laterally through the foramina of Luschka to circulate around the brain and spinal cord in the subarachnoid space. CSF is then reabsorbed into the venous circulation by the superior sagittal sinus through the arachnoid granulations projecting into the subarachnoid space. CSF is replaced approximately three to four times a day with approximately 400 to 500 mL produced per day.
In adults, the conus medullaris which marks the end of the spinal cord is usually located at the L1 or L2 vertebral levels. The subarachnoid space continues to the S2 vertebral level. The lumbar cistern is the enlargement of the subarachnoid space between the conus medullaris of the spinal cord and the end of the dura mater at the S2 vertebral level. The lumbar cistern, the site for performing the lumbar puncture, contains the lumbosacral nerve roots forming the cauda equina, the filum terminale, and cerebrospinal fluid.
4.3 Indications
4.3.1 Craniotomy
Lumbar drains are used to facilitate brain relaxation in cases for which significant brain retraction is expected to decrease postoperative cerebral edema. These cases include anterior skull base cases, retrosigmoid approaches, far lateral approaches, and suboccipital craniectomies, amongst others. 1 , 2 In these cases, the drain is generally placed preoperatively and clamped. During the procedure, if additional relaxation is required, the drain can be opened to drain the desired amount of CSF. The LD can then either remain in place postoperatively, or be removed at the end of the case.
4.3.2 Endoscopic Skull Base Surgery
Lumbar drains are commonly used in endoscopic skull base surgeries. These cases have a high rate of CSF leak because the dural defect is situated in a dependent location. An LD may be placed prior to or after an endoscopic endonasal approach to reduce intracranial pressure (ICP) to allow for the skull base defect to heal and prevent postoperative CSF leak. 3 The LD generally remains in place for a few days during the postoperative period, draining the desired amount each hour or every other hour, until satisfactory dural closure is suspected and the patient does not have any CSF leak.
4.3.3 CSF Leak
In cases of spontaneous or traumatic CSF leak, an LD can be placed prior to the attempted closure. This includes cases of CSF rhinorrhea, otorrhea, and spinal leaks. An added benefit of preoperative placement is the ability to administer intrathecal fluorescein. 4 The LD can then either be removed after performing the repair or be left in place during the postoperative period to facilitate dural closure. Placement of the LD significantly improves the rate of closure and limits the potential complications following a persistent CSF leak.
4.3.4 Normal Pressure Hydrocephalus
Patients who are being diagnosed with normal pressure hydrocephalus (NPH) can undergo LD placement as part of the workup. 5 If NPH is suspected based upon patient history, examination, and imaging findings, the patient is admitted and an LD is placed. Prior to placement, the patient is evaluated by physical therapy (PT). After drain placement, the desired amount of CSF is drained each day, and the patient undergoes daily PT evaluations to see if gait, balance, and gait speed improve. During LD placement, opening pressure can also be checked and CSF can be collected for analysis to confirm that the correct diagnosis is being made. If the patient improves clinically after LD placement, permanent CSF diversion with a ventriculoperitoneal or lumboperitoneal shunt is recommended. 6
4.3.5 Thoracoabdominal Aortic Surgery
Lumbar drains can also be placed for thoracoabdominal aortic surgery. Stenting or repair of the aorta can alter blood flow through important segmental arteries. LD placement allows for CSF diversion and thereby reduce pressure in the intrathecal space. This may increase spinal cord perfusion pressure and result in the reduction of ischemic injury to the spinal cord. 7
4.3.6 Miscellaneous
Lumbar drains can also be placed for a variety of other reasons. If a patient requires repeat sampling of CSF or repeat drainage in cases of communicating hydrocephalus, an LD can be placed. An LD can also be placed in cases of CSF leak following spine surgery.
4.4 Contraindications
The contraindications to the insertion of an LD include the following.
4.4.1 Intracranial Mass Lesion
A potential complication with placement of an LD is cerebral herniation, which can lead to compression of integral neurovascular structures and result in mortality. 8 Neuroimaging, either computed tomography (CT) or magnetic resonance imaging (MRI), is important to identify any pathology such as hematomas, hemorrhages, masses, and abscesses that can potentially increase the ICP resulting in shifting of the brain. Insertion of an LD can further exacerbate the brain herniation in cases of existing increased ICP by reducing the pressure within the spinal compartment.
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