From the Guidelines
Lumbar puncture (LP) is a crucial diagnostic tool for Normal Pressure Hydrocephalus (NPH) and should be performed in patients with suspected NPH, as it provides both diagnostic and therapeutic information, despite the potential risks of adverse events, such as headache and back pain, which are generally mild and manageable 1. The procedure involves measuring opening pressure and collecting cerebrospinal fluid (CSF) for analysis, and a positive tap test, defined as objective improvement in gait or cognition within 24-72 hours after LP, can support an NPH diagnosis and predict response to permanent shunting. Some key considerations for LP include:
- Patient position: lateral recumbent position is recommended to minimize the risk of complications 1
- Needle type and diameter: atraumatic needles with a smaller diameter (e.g., 22-24 G) may reduce the risk of post-LP headache and back pain 1
- CSF collection: free flow or dripping is recommended, and the patient's position during the procedure (lying or sitting) may affect the risk of adverse events 1
- Contraindications: increased intracranial pressure, coagulopathy, local infection, or severe degenerative spine disease should be ruled out before proceeding with LP 1 The benefits of LP in diagnosing NPH, including its ability to provide a positive tap test and predict response to shunting, outweigh the relatively low risk of complications, which can be mitigated with proper technique and patient selection 1. In terms of adverse events, the most common complications of LP include:
- Headache: typically mild and manageable, with an incidence ranging from 0.9% to 9.0% 1
- Back pain: also generally mild, with an incidence of around 17% 1
- Other adverse events: nausea, vomiting, dizziness, and vasovagal symptoms are less common, but can occur 1 Overall, LP is a valuable diagnostic tool for NPH, and its benefits in terms of diagnostic accuracy and therapeutic guidance outweigh the potential risks of adverse events, which can be minimized with proper technique and patient selection 1.
From the Research
Determining Normal Pressure Hydrocephalus (NPH) with Lumbar Puncture (LP)
- A lumbar puncture (LP) can be a useful diagnostic tool for Normal Pressure Hydrocephalus (NPH) as it allows for the removal of cerebrospinal fluid (CSF) and can provide temporary relief from symptoms 2, 3.
- Studies have shown that LP can improve gait disturbance, urinary incontinence, and cognitive impairment in NPH patients, with some patients experiencing prolonged improvement without the need for shunt operation 2.
- However, LP results alone may not be predictive of clinical outcome, and the presence of Alzheimer's pathology can affect the success of CSF shunting 4.
Diagnostic Criteria and LP
- NPH is typically diagnosed based on a triad of symptoms: ataxic gait, dementia, and urinary incontinence, and LP can be used to confirm the diagnosis 5.
- A high-volume lumbar puncture (HVLP) can be used to evaluate the response to CSF removal and predict the outcome of shunt surgery 4.
- The results of HVLP can vary between patients with NPH alone and those with concurrent Alzheimer's disease (NPH+AD), with the latter group showing a lower response rate to HVLP 4.
Alternative Treatment Options
- Repeated LP can be an alternative treatment option for selected NPH patients, particularly those who are not candidates for shunt operation due to high complication rates 2.
- Other treatment modalities, such as osteopathic manipulative treatment, may also be effective in improving symptoms in some patients 5.