INTRODUCTION — Lumbar puncture (LP) with examination of cerebrospinal fluid (CSF) is an important diagnostic tool for a variety of infectious and noninfectious neurologic conditions.
The techniques, indications, contraindications, and complications of LP in adults will be reviewed here. Technique of LP in children and for spinal and other types of neuraxial anesthesia is discussed separately. (See "Lumbar puncture: Indications, contraindications, technique, and complications in children" and "Spinal anesthesia: Technique" and "Epidural and combined spinal-epidural anesthesia: Techniques".)
Analysis of the CSF is discussed separately. (See "Cerebrospinal fluid: Physiology and utility of an examination in disease states".)
INDICATIONS — LP is essential or extremely useful in the diagnosis of bacterial, fungal, mycobacterial, and viral central nervous system (CNS) infections and, in certain settings, for help in the diagnosis of subarachnoid hemorrhage (SAH), CNS malignancies, demyelinating diseases, and Guillain-Barré syndrome.
Urgent — The number of definite indications for LP has decreased with the advent of better neuroimaging procedures including computed tomography (CT) scans and magnetic resonance imaging (MRI), but urgent LP is still indicated to diagnose two serious conditions [1,2]:
●Suspected CNS infection (with the exception of brain abscess or a parameningeal process).
●Suspected SAH in a patient with a negative CT scan [3]. The use of cerebrospinal fluid (CSF) examination in the evaluation of a patient with suspected SAH is discussed in detail separately. (See "Aneurysmal subarachnoid hemorrhage: Clinical manifestations and diagnosis", section on 'Lumbar puncture'.)
The most common use of the LP is to diagnose or exclude meningitis in patients presenting with some combination of fever, altered mental status, headache, or meningeal signs. Examination of the CSF has a high sensitivity and specificity for determining the presence of bacterial and fungal meningitis.
The findings on CSF analysis also may help distinguish bacterial meningitis from viral infections of the CNS. However, there is often substantial overlap. (See "Viral encephalitis in adults", section on 'Cerebrospinal fluid findings'.)
Nonurgent — A nonurgent LP is indicated in the diagnosis of many other conditions. The findings are discussed in the appropriate topic reviews:
●Idiopathic intracranial hypertension (pseudotumor cerebri)
●Carcinomatous meningitis
●Normal pressure hydrocephalus
●CNS syphilis
●CNS lymphoma
●Autoimmune encephalitis
Conditions in which LP is rarely diagnostic but still useful include:
●Multiple sclerosis
●Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy
●Paraneoplastic syndromes
●Neurosarcoidosis
●CNS vasculitis
LP is also required as a therapeutic or diagnostic maneuver in the following situations [1,2,4,5]:
●Spinal anesthesia
●Intrathecal administration of chemotherapy
●Intrathecal administration of antibiotics
●Injection of contrast media for myelography or for cisternography
CONTRAINDICATIONS — Although there are no absolute contraindications to performing the procedure, caution should be used in patients with:
●Possible raised intracranial pressure (ICP) with risk for cerebral herniation due to obstructive hydrocephalus, cerebral edema, or space-occupying lesion
●Thrombocytopenia or other bleeding diathesis, including ongoing anticoagulant therapy
●Suspected spinal epidural abscess
In many situations, high-risk patients can be identified and risks can be mitigated. These are discussed in detail in relation to the complications with which they are associated. (See 'Complications' below.)
When the LP is delayed or deferred in the setting of suspected bacterial meningitis, it is important to obtain blood cultures (which reveal the pathogen in more than half of patients) and promptly institute antibiotic therapy. Urgent evaluation and treatment of increased ICP, along with the administration of antibiotics and steroids, should be instituted promptly when this is suspected. Specific treatments are discussed separately. (See "Initial therapy and prognosis of bacterial meningitis in adults", section on 'Avoidance of delay'.)
TECHNIQUE — The choice of needle type (cutting versus atraumatic) and bore size can influence the risk of a post-LP headache, but also may increase the technical difficulty of the procedure. This is discussed in detail separately. (See "Post dural puncture headache", section on 'Prevention of PDPH after dural puncture'.)
Positioning — An LP can be performed with the patient in the lateral recumbent or prone positions or sitting upright. The lateral recumbent or prone positions are preferred over the upright position because they allow more accurate measurement of the opening pressure. The prone position is generally used for LPs performed under fluoroscopic guidance. (See 'Imaging guidance' below.)
The correct level of entry of the spinal needle is most easily determined with the patient sitting upright or standing. The highest points of the iliac crests should be identified visually and confirmed by palpation; a direct line joining these is a guide to the fourth lumbar vertebral body. However, this line may intersect the spine at points ranging from L1-L2 to L4-L5 [6], and tends to point to a higher spinal level in females and in patients with obesity [7]. The lumbar spinous processes of L3, L4, and L5, and the interspaces between, can usually be directly identified by palpation. The spinal needle can be safely inserted into the subarachnoid space at the L3-4 or L4-5 interspace, since this is well below the termination of the spinal cord in most patients. Spinal cord imaging is not considered necessary prior to LP, but, if performed, images should be reviewed to confirm the position of the conus prior to LP.
An alternate approach to obtaining cerebrospinal fluid (CSF) with a paramedian needle insertion through the L5-S1 space (Taylor approach) (figure 1) has been successfully used in a patient with advanced ankylosing spondylitis [8].
Correct patient positioning is an important determinant of success in obtaining CSF. The patient is instructed to remain in the fetal position with the neck, back, and limbs held in flexion. The lower lumbar spine should be flexed with the back perfectly perpendicular to the edge of a bed or examining table. The hips and legs should be parallel to each other and perpendicular to the table. Pillows placed under the head and between the knees may improve patient comfort.
Aseptic technique — The overlying skin should be cleaned with alcohol and a disinfectant such as povidone-iodine or chlorhexidine (0.5 percent in alcohol 70 percent); the antiseptic should be allowed to dry before the procedure is begun. Many product inserts of chlorhexidine-containing solutions warn against use of chlorhexidine prior to LP because of a concern that it can cause arachnoiditis. The evidence that it does so is very limited, and many experts believe that chlorhexidine has an advantage over povidone-iodine because of its onset, efficacy, and potency [9-13]. Due to specific labeling prohibiting use, a formal institutional policy to support such use may be indicated. After the skin is cleaned and allowed to dry, a sterile drape with an opening over the lumbar spine is placed on the patient.
Face masks should be used by individuals who place a catheter or inject material into the spinal canal as recommended by the Healthcare Infection Control Practices Advisory Committee and the Centers for Disease Control and Prevention (CDC) [14]. While routine use of face masks during diagnostic LP and neuroradiologic imaging procedures involving LP has been recommended by some [15-17], others question the practicality and necessity of the use of face masks since infections are rare and there is no proof that face masks prevent such infections [18,19]. However, we believe a face mask should be used for diagnostic procedures if the procedure is likely to be prolonged or difficult, or if the person carrying out the procedure has an upper respiratory tract infection. (See "Infection prevention: Precautions for preventing transmission of infection".)
Procedure technique — Local anesthesia (eg, lidocaine) is infiltrated into the previously identified lumbar intervertebral space and a 20- or 22-gauge spinal needle containing a stylet is inserted into the lumbar intervertebral space.
The spinal needle may be advanced slowly, angling slightly toward the head, as if aiming towards the umbilicus. The flat surface of the bevel of the needle should be positioned to face the patient's flanks to allow the needle to spread rather than cut the dural sac (the fibers of which run parallel to the spinal axis). The approximate distance of the epidural space from the skin is 45 to 55 mm on average but is variable and may be longer in patients with obesity [7,20,21]. Many clinicians choose to advance the needle incrementally, removing the stylet periodically to check for CSF flow, then reinserting the stylet until the subarachnoid space is entered [22]. Some report a higher rate of successful LP when the stylet is removed, just after the skin is punctured and before it is passed into the subarachnoid space in order to better observe the flow of CSF upon entry of the subarachnoid space [23,24]; however, this technique may be associated with a risk of epidermoid tumor, possibly infection, or failure to get flow of CSF. (See 'Epidermoid tumor' below.)
Once CSF appears and begins to flow through the needle, a manometer should be placed over the hub of the needle (figure 2). The patient should be instructed to slowly straighten or extend the legs to allow free flow of CSF within the subarachnoid space and the opening pressure should be measured. While the pressure measurement is affected by the position of the legs, the available evidence suggests that the effect is likely to be small. In one review, pressures were elevated by only 1 to 2 cm H2O in four of five studies studying this effect; however, in one study, changing position from a straight to a fully flexed position resulted in an increase in pressure of 6.4 mmHg (approximately 8.7 cm H2O) [25]. Opening pressure does not appear to be significantly different if measured in the prone or lateral recumbent position [26]. Fluid is then serially collected in sterile plastic tubes. A total of 8 to 15 mL of CSF is typically removed during routine LP. However, when special studies are required, such as cytology or cultures for organisms that grow less readily (eg, fungi or mycobacteria), 40 mL of fluid can safely be removed. Aspiration of CSF should not be attempted, as it may increase the risk of bleeding [22]. The stylet should be replaced before the spinal needle is removed, as this can reduce the risk of post-LP headache. (See "Post dural puncture headache", section on 'Procedural risk factors'.)
No trials have shown that bed rest following LP significantly decreases the risk of post-LP headache compared with immediate mobilization [27,28]. (See "Post dural puncture headache", section on 'Prevention of PDPH after dural puncture'.)
The Queckenstedt maneuver can be used to demonstrate that there is free flow of fluid from the ventricles to the lumbar space. This maneuver is performed by measuring the CSF pressure and then observing the change in pressure after manual compression of both jugular veins. However, this test is rarely useful in modern practice, since newer techniques such as magnetic resonance imaging (MRI) and computed tomography (CT) readily identify most obstructing spinal or basilar lesions.
Imaging guidance — Imaging guidance is typically reserved for patients with difficult anatomy and/or unsuccessful LP attempts.
Fluoroscopy — Fluoroscopic guidance for LP may be required if attempts without imaging are unsuccessful. This is also suggested for patients with obesity or have difficult anatomy because of prior spine surgery or other reasons. Most neuroradiologists perform fluoroscopically guided LPs in the L2-L3 or L3-L4 intervertebral space with the patient in the prone position [29]. In addition to improving success rates, fluoroscopic guidance may reduce the incidence of traumatic LP [30]. However, patients undergoing fluoroscopy must be rotated from the prone to the lateral decubitus position in order to accurately measure opening pressure, and this is often not done in clinical practice [29].
Ultrasound — Imaging guidance may also be obtained with ultrasound [31,32]. A meta-analysis of 14 randomized trials (1334 patients) that compared LPs and epidural catheterizations performed with ultrasound with those performed without imaging found that ultrasound guidance reduced the risk of failed and traumatic procedures (risk ratio [RR] = 0.21 and 0.27, respectively), as well as the number of needle insertions and redirections [33]. A subsequently published randomized trial involving 100 adult patients undergoing LP in the emergency department found no significant difference in outcomes with ultrasound guidance [34].
The use of ultrasound in spinal anesthesia is discussed separately. (See "Spinal anesthesia: Technique", section on 'Preprocedure ultrasonography'.)
COMPLICATIONS — LP is a relatively safe procedure, but minor and major complications can occur even when standard infection control measures and good technique are used. These complications include:
●Post-LP headache
●Infection
●Bleeding
●Cerebral herniation
●Minor neurologic symptoms such as radicular pain or numbness
●Late onset of epidermoid tumors of the thecal sac
●Back pain
The risk of complications was studied in a cohort of 376 patients who underwent LP for evaluation of acute cerebrovascular disease [35]. The following frequency of complications was noted: backache (25 percent), headache (22 percent), headache and backache (12 percent), severe radicular pain (15 percent), and paraparesis (1.5 percent). Severe pain or paraparesis occurred in 6.7 percent of patients receiving anticoagulants following the procedure and in none of the 34 patients who did not receive anticoagulants.
Post-LP headache — Headache, which occurs in 10 to 30 percent of patients, is one of the most common complications following LP. Post-LP headache is caused by leakage of cerebrospinal fluid (CSF) from the dura and traction on pain-sensitive structures. Patients characteristically present with frontal or occipital headache within 24 to 48 hours of the procedure, which is exacerbated in an upright position and improved in the supine position. Associated symptoms may include nausea, vomiting, dizziness, tinnitus, and visual changes.
This risk factors, prevention, and treatment of post-LP headache are discussed separately. (See "Post dural puncture headache".)
Infection — Infections are rare after LP; in typical patients no techniques beyond usual aseptic technique are required. (See 'Aseptic technique' above.)
Meningitis is an uncommon complication of LP. In a review of 179 cases of post-LP meningitis reported in the medical literature between 1952 and 2005, half of all cases occurred after spinal anesthesia; only 9 percent occurred after diagnostic LP. The most commonly isolated causative organisms were Streptococcus salivarius (30 percent), Streptococcus viridans (29 percent), alpha-hemolytic strep (11 percent), Staphylococcus aureus (9 percent), and Pseudomonas aeruginosa (8 percent) [36].
An LP through a spinal epidural abscess can result in the spread of bacteria into the subarachnoid space. Because an LP is not needed for diagnosis, the procedure should not be performed in most patients with suspected epidural abscess in the lumbar region [37]. (See "Spinal epidural abscess".)
While some cases of post-LP meningitis due to staphylococci, pseudomonas, and other gram-negative bacilli have been attributed to contaminated instruments or solutions or poor technique [38], other studies have suggested that post-LP meningitis could arise from aerosolized oropharyngeal secretions from personnel present during the procedure, especially since many of the causative organisms are found in the mouth and upper airway [18,36,39,40].
Bacteremia is not a contraindication to LP. Because meningitis can be caused in animals by performing an LP after first inducing a bacteremia [41,42], some authors have speculated that an LP in a bacteremic patient without preexisting meningitis might actually cause meningitis [43]. However, this phenomenon is rare, if it occurs at all. In a retrospective study of 1089 bacteremic infants, the incidence of spontaneous meningitis in children who underwent LP and subsequently developed meningitis was not statistically different from those who did not undergo LP (2.1 versus 0.8 percent) [44]. We and other authors believe that theoretical concerns about inducing meningitis in patients with bacteremia should not be used as the basis to forego LP if meningitis is suspected [19].
There are rare case reports of discitis and vertebral osteomyelitis following LP. Most cases were due to normal skin flora such as Cutibacterium species and coagulase negative staphylococci [45-47]. These complications presumably result from direct inoculation of bacteria into the vertebral bone.
Bleeding — The CSF is normally acellular, although up to five red blood cells (RBCs) are considered normal after LP due to incidental trauma to a capillary or venule. A higher number of RBCs is seen in some patients in whom calculation of the white blood cell (WBC)-to-RBC ratio and the presence or absence of xanthochromia may differentiate LP-induced from true central nervous system (CNS) bleeding. (See "Cerebrospinal fluid: Physiology and utility of an examination in disease states", section on 'Cells'.)
Incidence — Serious bleeding that results in spinal cord compromise is rare in the absence of bleeding risk [48]. Patients who have thrombocytopenia or other bleeding disorders or those who received anticoagulant therapy prior to or immediately after undergoing LP have an increased risk of bleeding. This risk may be further increased with other factors that increase bleeding risk, such as traumatic or repeated taps.
In one series, spinal hematoma developed in 7 of 342 patients (2 percent) who received anticoagulant therapy after undergoing LP; five of these patients developed paraparesis [35]. In one literature review, 47 percent of 21 published cases of spinal hematoma following LP occurred in patients with a coagulopathy [49]. Thus, a high index of suspicion of spinal hematoma should be maintained in all patients who develop neurologic symptoms after an LP, including those with no known coagulopathy. In rare cases, intraventricular, intracerebral, and subarachnoid hemorrhage (SAH) have also been reported as complications of LP [50,51].
Reducing risk — We are unaware of any study that has systematically examined interventions to reduce the risk of bleeding following LP based upon the degree of thrombocytopenia or clotting study abnormalities. Thus, at present the only guidepost is "clinical judgment."
We generally advise not performing an LP in patients with coagulation defects who are actively bleeding, have severe thrombocytopenia (eg, platelet counts <50,000 to 80,000/microL), or an international normalized ratio (INR) >1.4, without correcting the underlying abnormalities [52,53].
When an LP is considered urgent and essential in a patient with an abnormal INR or platelet count in whom the cause is not obvious, consultation with a hematologist may provide the best advice for safe correction of the coagulopathy prior to performing the LP. In one series, 37 patients anticoagulated with vitamin K antagonists received prothrombin complex concentrate prior to emergency LP; INR reversal was successful in 33 patients within a median 135 minutes; however, two patients experienced a thromboembolic event (stroke, myocardial infraction) and one clinically irrelevant intracranial subdural hematoma developed [54], suggesting that risks and benefits should be carefully assessed in individual patients. (See "Diagnostic approach to the adult with unexplained thrombocytopenia", section on 'General management principles' and "Platelet transfusion: Indications, ordering, and associated risks", section on 'Preparation for an invasive procedure'.)
For elective procedures in a patient receiving systemic anticoagulation, observational studies and expert opinion have suggested stopping the agents for a specified time period prior to spinal anesthesia or LP (table 1) [55-57]:
●Unfractionated intravenous heparin drips – Two to four hours.
●Low-molecular-weight heparin – 12 to 24 hours.
●Warfarin – Five to seven days.
●Newer oral anticoagulants (NOACs), apixaban, edoxaban, and rivaroxaban – 72 hours. Dabigatran should be held 48 to 96 hours based on renal function.
●Subcutaneous heparin – <10,000 units per day is not believed to pose a substantial risk for bleeding.
None of these approaches have been carefully assessed for efficacy or risk, and all presume that the underlying indications for anticoagulation therapy allow a temporary suspension of treatment.
While the optimal timing of restarting anticoagulation after LP is not known, the incidence of spinal hematoma in one series was much lower when anticoagulation was started at least one hour after the LP [35]. NOACs can be restarted six to eight hours after an atraumatic spinal or epidural anesthesia or clean LP; however, in traumatic procedures with increased risk of bleeding, the guidelines recommend restarting NOACs 48 to 72 hours after complete hemostasis [57].
Antiplatelet therapy with aspirin and nonsteroidal antiinflammatory agents has not been shown to increase the risk of serious bleeding following LP. In a prospective study of 924 patients who underwent orthopedic procedures with spinal or epidural anesthesia, 386 patients were taking antiplatelet therapy prior to surgery; 193 were taking aspirin [58]. Neither aspirin nor any other antiplatelet agents were associated with an increased risk of bleeding. However, none of these patients were taking clopidogrel, ticlopidine, or a GP IIb/IIIa receptor antagonist. Female sex, increased age, a history of excessive bruising/bleeding, hip surgery, continuous catheter anesthetic technique, large needle gauge, multiple needle passes, and moderate or difficult needle placement were all significant risk factors for minor bleeding at the site of catheter placement [58]. Given the unknown risk of bleeding with thienopyridine derivatives (clopidogrel, ticlopidine, prasugrel, ticagrelor), it may be reasonable to suspend treatment with these agents, when possible, for one to two weeks prior to an elective LP, while pharmacologic data suggest that for GP IIb/IIIa receptor antagonists, a shorter period of treatment cessation (8 hours for tirofiban and eptifibatide and 24 to 48 hours for abciximab) may be indicated [56].
In all cases, the relative risk of performing an LP has to be weighed against the potential benefit (eg, diagnosing meningitis due to an unusual or difficult to treat pathogen). In cases in which LP is considered necessary but the risk of bleeding is considered to be high, it may be useful to perform the procedure under fluoroscopy to reduce the chance of accidental injury to small blood vessels.
Issues regarding neuraxial anesthesia in patients receiving anticoagulation or antiplatelet therapy are discussed separately. (See "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication".)
Management of spinal hematoma — The diagnosis of spinal hematoma is complicated by the concealed nature of the bleeding; thus, a high index of suspicion must be maintained. Patients who have persistent back pain or neurologic findings (eg, weakness, decreased sensation, or incontinence) after undergoing LP require urgent evaluation (usually spinal magnetic resonance imaging [MRI]) for possible spinal hematoma [59].
The appropriate treatment for patients with significant or progressing neurologic deficits is prompt surgical intervention, usually a laminectomy, and evacuation of the blood. Timely decompression of the hematoma is essential to avoid permanent loss of neurologic function [60,61]. Patients with mild symptoms or early signs of recovery may be managed conservatively with vigilant monitoring; dexamethasone may be administered to mitigate neurologic injury [49,50]. (See "Disorders affecting the spinal cord", section on 'Spinal epidural hematoma'.)
Cerebral herniation — The most serious complication of LP is cerebral herniation. Suspected increased intracranial pressure (ICP) due to an intracranial mass lesion, cerebral edema, or obstructive hydrocephalus is a relative contraindication to performance of an LP and also requires independent assessment and treatment.
Incidence — The magnitude of the risk was evaluated in a report of 129 patients with increased ICP: 15 patients (12 percent) had an unfavorable outcome within 48 hours of LP [62]. Similar findings were noted in a series of 55 patients with SAH: seven patients (13 percent) experienced neurologic deterioration during or soon after an LP, six of whom had evidence of cerebral dislocation [63]. In another series of 1533 patients with bacterial meningitis, 47 (3 percent) had a clinical deterioration after LP [64]. Cardiorespiratory collapse, loss of consciousness, and death may follow. (See "Evaluation and management of elevated intracranial pressure in adults".)
A 1969 study of 30 patients with increased ICP who deteriorated after LP attempted to identify the clinical features of patients who were at greatest risk for this complication [65]. The following findings were noted: 73 percent had focal findings on neurologic examination (including dysphagia, hemiparesis, and cranial nerve palsies), 30 percent had documented papilledema prior to the LP, and 30 percent had evidence of increased ICP on plain skull films (erosion of the posterior clinoid processes). Deterioration occurred immediately in one-half of the patients, with the remainder declining within 12 hours. A more recent series compared patients who did and did not deteriorate after LP and found that interrater reliability regarding the presence of a contraindication on computed tomography (CT) was only moderate (kappa = 0.47) and that a similar proportion of patients in both groups had such a contraindication (14 versus 11 percent) [64].
Indications for CT scan — The concern about this serious complication has resulted in routine CT scanning prior to LP being the standard of care in many emergency departments. At one institution, for example, 78 percent of patients with suspected meningitis underwent CT scanning before the LP was performed [66]. However, this practice, when applied to patients with suspected bacterial meningitis, delays the performance of LP, which in turn may delay treatment or limit the diagnostic power of CSF analysis when performed after antibiotic administration. Moreover, CT scanning is not necessary in all patients prior to LP and may not be adequate to exclude elevated ICP in others [67,68]. Some studies suggest that high-risk patients can be identified, allowing the majority of patients to safely undergo LP without screening CT [66,69]. This was best illustrated in a prospective study of 301 adults with suspected meningitis [66]. The following findings were noted:
●Among the 235 (78 percent) who underwent CT scan before LP, 24 percent had an abnormal finding but only 5 percent (11 patients) had a mass effect
●The risk of an abnormal CT scan was associated with specific clinical features (presence of impaired cellular immunity, history of previous CNS disease, or a seizure within the previous week), as well as certain findings on neurologic examination (reduced level of consciousness, and focal motor or cranial abnormalities)
●Among 96 patients with none of these abnormalities, only three had an abnormal CT scan; one of the three misclassified patients had a mild mass effect, but all three underwent LP without herniation
●Compared with patients who did not undergo CT scan before LP, those who underwent CT scan before LP had an average of a two-hour delay in diagnosis and a one-hour delay in therapy
Based upon these observations, we do not perform a CT scan before an LP in patients with suspected bacterial meningitis unless one or more risk factors is present:
●Altered mentation
●Focal neurologic signs
●Papilledema
●Seizure within the previous week
●Impaired cellular immunity
Patients with these clinical risk factors should have a CT scan to identify possible mass lesion and other causes of increased ICP. Mass lesions causing elevated ICP are usually easily identified on CT scan. However, the CT scan should also be scrutinized for more subtle signs including diffuse brain swelling as manifest by loss of differentiation between gray and white matter and effacement of sulci, as well as ventricular enlargement and effacement of the basal cisterns [70].
Management of elevated intracranial pressure — Independent of the decision to perform LP, patients with possible elevated ICP based upon the above clinical features may require urgent life-saving interventions to lower ICP that may include head elevation, hyperventilation to a partial pressure of carbon dioxide (PCO2) of 26 to 30 mmHg, and intravenous mannitol (1 to 1.5 g/kg). When indicated, these should not await CT scan. These same measures should be instituted if a patient develops signs of herniation after LP. The evaluation and management of patients with elevated ICP is discussed in detail separately. (See "Evaluation and management of elevated intracranial pressure in adults", section on 'Urgent situations'.)
Other complications
Epidermoid tumor — The formation of an epidermoid spinal cord tumor is a rare complication of LP that may become evident years after the procedure is performed [71-73]. Most reported cases are children ages 5 to 12 years who had an LP in infancy; however, this has also been described in adults [74-76]. It may be caused by epidermoid tissue that is transplanted into the spinal canal during LP without a stylet, or with one that is poorly fitting. This complication probably can be avoided by using spinal needles with tight-fitting stylets during LP [77,78].
Abducens palsy — Both unilateral and bilateral abducens palsy are reported complications of LP [79-81]. This is believed to result from intracranial hypotension and is generally accompanied by other clinical features of post-LP headache. Most patients recover completely within days to weeks. Other cranial nerve palsies are rarely reported [82].
Radicular symptoms and low back pain — It is not uncommon (13 percent in one series) for patients to experience transient electrical-type pain in one leg during the procedure [83]. However, more sustained radicular symptoms or radicular injury appear to be rare [84].
Up to one-third of patients complain of localized back pain after LP; this may persist for several days, but rarely beyond [83].
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Post dural puncture headache".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Lumbar puncture (spinal tap) (The Basics)" and "Patient education: Spinal headache (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Indications – Lumbar puncture (LP) is essential or extremely useful in the diagnosis of bacterial, fungal, mycobacterial, and viral central nervous system (CNS) infections and, in certain settings, for help in the diagnosis of subarachnoid hemorrhage (SAH), CNS malignancies, demyelinating diseases, and Guillain-Barré syndrome. (See 'Indications' above.)
When the LP is delayed or deferred in a patient with suspected meningitis, it is important to obtain blood cultures and promptly institute antibiotic therapy. (See "Initial therapy and prognosis of bacterial meningitis in adults", section on 'Avoidance of delay'.)
●Avoiding infectious complications – Meningitis and other infections are rare complications of LP. (See 'Infection' above.)
•LP is contraindicated in patients with a suspected spinal epidural abscess.
•Suspected bacteremia is not a contraindication to LP.
•We suggest the use of a face mask for diagnostic LP if the procedure is expected to be prolonged or difficult or if the operator has an upper respiratory tract infection.
●Avoiding hemorrhage – Bleeding in the epidural or subdural space following LP may occur in up to 2 percent of patients, primarily in those patients with thrombocytopenia or other bleeding disorders or in those who have received anticoagulant therapy. (See 'Bleeding' above.)
•Antiplatelet therapy with aspirin and nonsteroidal antiinflammatory agents is not clearly associated with an increased risk of bleeding after LP. The bleeding risk associated with other antiplatelet agents is unknown. It is reasonable to suspend therapy with these agents, when possible, prior to elective LP.
•Anticoagulation therapy is generally suspended, when possible, prior to elective LP. Specific time frames for suspending therapy depend on the agent and are discussed above.
•We recommend not performing an LP in patients with coagulation defects who are actively bleeding, have severe thrombocytopenia (eg, platelet counts <50,000 to 80,000/microL), or have an international normalized ratio (INR) >1.4, without correcting the underlying abnormalities.
•When an LP is considered essential in this setting, consultation with a hematologist may provide the best advice for safe correction of the coagulopathy prior to LP.
●Avoiding cerebral herniation – Cerebral herniation is a rare, but usually fatal, complication of an LP performed in an individual with increased intracranial pressure (ICP). While routine neuroimaging, usually brain computed tomography (CT), before LP is not indicated in all patients, those with suspected increased ICP (altered mentation, focal neurologic signs, papilledema, recent seizure, and impaired cellular immunity) should have a CT scan to rule out possible mass lesion and other causes of increased ICP. (See 'Cerebral herniation' above.)
Independent of a decision to perform LP, patients with suspected elevated ICP may require urgent interventions to lower ICP. (See "Evaluation and management of elevated intracranial pressure in adults", section on 'Urgent situations'.)
●Other complications – LP is a relatively safe procedure, but minor and major complications can occur, including headache and minor neurologic symptoms, such as radicular pain or numbness. (See 'Complications' above.)
