Understanding Continuous Lumbar CSF Drainage for NPH

Continuous Lumbar CSF Drainage for NPH: A Diagnostic Tool

Continuous lumbar cerebrospinal fluid (CSF) drainage is a commonly employed procedure usually done in the hospital.  It’s mainly used to help doctors figure out if a permanent treatment, like shunt surgery, would work to relieve symptoms of normal pressure hydrocephalus (NPH). By draining CSF from the lumbar spine for one to three days, many patients with NPH will experience a temporary improvement in their symptoms.  If such improvement is noted, permanent benefit would be expected from a shunt operation.

What is Continuous Lumbar CSF Drainage?

Continuous lumbar CSF drainage involves inserting a catheter into the lumbar region (lower spine).  The spinal cord and the nerves within the lumbar spinal canal below the spinal cord are bathed in CSF.  This CSF is continuous with the CSF in the brain.  Draining fluid from the lumbar spine, therefore, allows the fluid in the brain to be drained in a minimally invasive fashion.

During the procedure, the fluid is continuously drained by gravity into an external collection reservoir at a rate that is a bit slower than the rate of CSF production.  The effect is to lower pressure within the head and, in doing so, provide temporary improvement in gait.  Improvement in bladder function can also be seen, and sometimes cognitive benefit occurs as well.

It is important to appreciate that this procedure can only provide temporary relief.  It is rare for the effect to persist beyond 1 week after drainage is completed, and the typical duration of benefit is only 1 to 3 days.  The goal is to reproduce the physiologic effect of a shunt operation and help physicians estimate if a shunt will prove helpful more permanently.  If clear improvement is observed following drainage, the diagnosis of NPH is secured, and a shunt can be predicted to alleviate symptoms with over 90% certainty.

It is also important to appreciate that perhaps as many as 40% of patients who do not improve with lumbar drainage will still benefit from a shunt.  A negative response to lumbar drainage does not, therefore, eliminate the possibility that a shunt will be helpful.  In medicine, we say that this test has a high positive predictor value but a relatively low negative predictor value.

Procedure Details

The procedure for continuous lumbar CSF drainage involves several key steps:

1. Catheter Insertion: A catheter is inserted into the lumbar region of the spine through a small puncture in the skin.  This is often done in a neurosurgical ICU under local anesthesia with light sedation.  Occasionally, it is done in the operating room with general anesthesia. The tubing attached to the catheter is typically anchored to the skin of the back with a few sutures to prevent it from dislodging.
2. Draining the CSF: The catheter tubing is then connected to an external drainage system, such as a collection bag, that continuously collects the drained CSF. The drainage rate is carefully controlled to prevent complications.
3. Monitoring: During the procedure, patients are often monitored for changes in symptoms. Healthcare providers may assess whether there is improvement in gait, cognition, and urinary control.  More commonly, patients are allowed to leave the hospital after the catheter is removed and are instructed to resume their typical daily activities. They can then self-monitor for subjective improvement in their symptoms.  Their caregivers and family members can also observe for potential improvement.  Patients are often invited to return to the office for more quantitative measurements of their response.
4. Patient Experience: This procedure is generally performed in a hospital setting, and patients may need to stay for several days while the drainage occurs. Healthcare providers monitor the patient’s condition and ensure the drainage system is functioning properly.

Follow-up Care

After the procedure, patients require careful follow-up to assess the effectiveness of the drainage and any potential complications:

1. Monitoring for Complications: Continuous lumbar CSF drainage is generally well tolerated and safe. Occasionally, patients experience headache or nausea during the procedure, which may be an indication of overdrainage.  This can be easily treated by slowing the rate of CSF diversion.  Back pain or pain radiating into the lower limbs can sometimes occur.  This is a temporary problem that tends to resolve when the catheter is removed.  It may, however, require administration of pain medications during the hospital admission and for several days after discharge.  A very rare complication is infection, which may be suspected if a fever develops.

Patient Considerations

Not all patients are candidates for continuous lumbar CSF drainage. Criteria for patient selection include:

1. Good Candidates:
   • Patients with NPH who are otherwise deemed medically able to tolerate ventricular shunt surgery or other permanent neurosurgical treatment.
   • Patients who are deemed able to tolerate the admission without requiring sedating psychiatric medications that could make it difficult to interpret the clinical response.

2. Not Suitable for Lumbar CSF Drainage:
   • Patients with severe spinal stenosis, active infections, or who are receiving blood-thinning medications.
   • Individuals who are unable to tolerate the procedure due to underlying health conditions.

Long-Term Impact

Continuous lumbar CSF drainage offers temporary relief and serves as a vital diagnostic tool. However, it is not a permanent solution. Its role in managing NPH and hydrocephalus includes:

1. Bridge to Permanent Treatment: For patients who respond well to CSF drainage, the procedure helps guide decisions about permanent treatments, such as shunt placement. If significant symptom improvement occurs, it suggests that shunt surgery may be an effective long-term solution.
2. Improved Symptom Relief: In some cases, even before permanent treatment is established, patients experience significant symptom relief, improving their quality of life.
3. Ongoing Monitoring: Patients who undergo lumbar CSF drainage should continue to be monitored for complications and follow up regularly to assess their condition. If the patient is not a candidate for permanent shunt placement, other management options may be considered.

Conclusion: A Diagnostic Step Toward Long-Term Management

Continuous lumbar CSF drainage is a commonly employed procedure for diagnosing and assessing NPH. It provides temporary symptom relief and essential information that guides decisions about permanent treatments like shunt surgery. While not a long-term solution, it plays a key role in determining whether patients will benefit from more permanent interventions. Proper patient selection, monitoring, and follow-up care are essential to achieving the best outcomes.

Information you can trust! This article was produced by the Hydrocephalus Association, copyright 2024. We would like to thank James B. Golomb, MD, for his valuable contribution and expert input.

This article is designed to provide helpful information on the subjects discussed. It is not intended as a substitute for treatment advice from a medical professional. For diagnosis or treatment of any medical condition, consult your doctor.