on 23-Oct-2022 (Sun)

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'.)

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

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.)

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'.)

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.

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

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].

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]

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 H ₂O 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]

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.

No trials have shown that bed rest following LP significantly decreases the risk of post-LP headache compared with immediate mobilization [27,28].

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

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].

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.

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.

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].

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.

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.

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

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]

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]

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.

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]

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].

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

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].

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].

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

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'.)

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]

Post dural puncture headache (PDPH), also known as post lumbar puncture (LP) headache, is a common complication of diagnostic LP. It also can occur following spinal anesthesia or, more commonly, inadvertent dural puncture during attempted epidural catheter placement. The headache is usually positional (worse when upright, better when lying flat) and is often accompanied by neck stiffness, photophobia, nausea, or subjective hearing symptoms

The precise etiology of headache after dural puncture is unclear, but is thought to relate to leakage of cerebrospinal fluid (CSF) through the dural hole created by the needle.

However, not all patients with PDPH have low CSF pressure, and not all patients with significant CSF leak develop a headache.

hree pathophysiologic mechanisms have been proposed:

● CSF hypotension results in compensatory meningeal venodilation and blood volume expansion, with headache caused by acute venous distention. This mechanism is consistent with magnetic resonance imaging (MRI) in several reported cases of PDPH [1,2].

● Intracranial hypotension related to CSF leak may cause sagging of intracranial structures and stretch of sensory intracranial nerves, causing pain and cranial nerve palsies. In one study of seven patients with intracranial hypotension, MRI findings of downward displacement of the brain were associated with headache, and resolved along with the headache symptoms [3]. Traction of the upper cervical nerves may cause PDPH associated neck, back and shoulder pain [4].

● Altered craniospinal elasticity after lumbar puncture (LP) results in increased caudal compliance relative to intracranial compliance and acute intracranial venodilation in the upright position [5].

The incidence of PDPH varies widely, depending on patient (eg, age, gender, pregnancy, body mass index [BMI]) and procedural (eg, needle size and type, bevel orientation for cutting needles) risk factors.

PDPH after lumbar puncture (LP) occurs in approximately 11 percent of cases when a standard, traumatic needle is used [9].

Patient risk factors — In various studies, common patient risk factors for PDPH have included female gender, pregnancy, age 18 to 50 years compared with older or younger ages, and a prior history of headache

Age – In most studies, extremes of age are associated with lower incidence of PDPH, with young adults (18 to 50 years of age) having the highest risk [23,24,31,37-39]. As an example, in one prospective study of patients who had spinal anesthesia with 25 or 27 gauge Quincke (ie, traumatic) needles, PDPH occurred in 11 percent of patients aged 31 to 50 years, compared with 4 percent of others [24].

Prior headaches – History of prior headaches (both PDPH and chronic headaches) may be a risk factor for PDPH [4,23,31-33]; although, this has not been observed in all studies [34-36]

Pregnancy – Pregnancy confers an additional risk for PDPH, possibly due to increased cerebral vasodilation in response to cerebrospinal fluid (CSF) hypotension, related to high levels of circulating estrogen [24,26].

Female gender – Several studies have found that women have a two to three times increased risk for PDPH compared with men [23-25]

Low opening pressure – Low opening pressure during lumbar puncture (LP) may also predict an increased risk of PDPH [42]. However, a 2019 case-control retrospective study and systematic literature review found no association between either opening pressure or closing pressure and PDPH risk [43]

Volume of CSF removed – PDPH may have distinct temporal and prognostic profiles depending on the volume of CSF removed, particularly for high volume CSF removal. A systematic literature review found that high volume CSF removal (ie, 20 to 30 mL) may be associated with increased risk of immediate PDPH, but decreased risk of PDPH at 24 hours, compared with lower volume CSF removal [43].

High volume CSF removal with lowered closing pressure may help reduce further CSF leakage to heal the dural hole

Low body mass index (BMI) – The literature on the effect of BMI on the risk of PDPH is inconclusive

Procedural risk factors — The choice of spinal needle and procedural factors can affect the risk of PDPH. We suggest the use of pencil point (atraumatic) needles for spinal anesthesia and diagnostic LP.

Needle tip – For both diagnostic LP and spinal anesthesia, we recommend the use of spinal needles with a pencil point tip, rather than needles with a sharp cutting tip. The use of pencil point spinal needles reduces the risk of PDPH compared with cutting needles of the same size [8,52-54]

The incidence of PDPH was significantly lower in the atraumatic group compared with the conventional group (4.2 versus 11 percent, relative risk [RR] 0.40, 95% CI 0.34-0.47, absolute risk reduction 6.8 percent, number needed to treat to avoid one headache 15)

In addition, use of atraumatic needles was associated with a significant reduction in the need for EBP (RR 0.5, 95% CI 0.33-0.75). There was no significant difference between groups for the success rate of LP on first attempt, LP failure rate, incidence of traumatic tap, or backache.

Needle size – Larger conventional needle size (ie, lower needle gauge) is correlated with an increased incidence of PDPH, as demonstrated in a 2016 meta-analysis that included 12 studies with over 3100 patients who had neuraxial anesthesia with cutting needles [55]. As examples from the meta-analysis, the incidence of PDPH with a 22 or 23 gauge Quincke needle ranged from 8 to 25 percent, whereas the incidence of PDPH with a 27 gauge Quincke needle ranged from 0 to 14 percent

Smaller spinal needles may be technically more difficult to use, as they tend to bend during insertion. Thus they are typically used with an introducer needle, which is inserted through the skin and along the desired needle path. Flow rate is slower than with larger bore needles; confirmatory CSF appears more slowly in the needle hub, and collection of CSF is slower. In our practice, spinal anesthesia is performed using a small gauge noncutting needle (ie, 25 gauge Whitacre).

The optimal size of spinal needle may be different for spinal anesthesia versus diagnostic LP in which opening pressure and/or CSF sampling is required. In one laboratory study that compared flow rates and the rate of accurate pressure transduction for various cutting and pencil point spinal needles, the 20 gauge Sprotte needles provided rapid pressure transduction (>90 percent of true pressure within one minute) and an optimal flow rate, defined as 2 mL per minute. [56].

Needle orientation – PDPH is more than twice as likely if a cutting spinal or epidural needle is inserted with the bevel perpendicular, rather than parallel, to the long axis of the spine [31,57-59]. As an example, in one study, 218 patients who underwent nonobstetric surgery with spinal anesthesia using a 27 gauge Quincke needle were randomly assigned to have the needle inserted parallel or transverse to the long axis of the spine [59]. PDPH occurred in 4 percent of patients in the parallel group, and 23 percent of patients in the transverse group

Reinsertion of stylet – Whether reinserting the stylet before removing the spinal needle reduces the risk of PDPH is unclear. Available data suggest that reinsertion does not reduce PDPH when a cutting needle is used, and the data regarding the use of pencil point needles is equivocal. Authors to this topic do not routinely reinsert the stylet before removing a spinal needle

Placement of spinal needle in the sitting as opposed to lateral position [66] and a higher number of needle passes may be associated with increased risk for PDPH in spinal anesthetics, but the evidence is conflicting [31,67].

Paramedian approach to the spinal space and decreased operator experience [68,69] may confer additional increased risk for PDPH, but results are limited and conflicting between the orthopedic and obstetric populations [70,71].

In epidural placements, studies have failed to show a difference in PDPH risk with the use of air versus saline for the loss of resistance technique to identify the epidural space across all patient populations [72,73]. The onset of headache may be sooner in obstetric patients when air is used for loss of resistance, likely related to pneumocephalus rather than low pressure headache [20]

Bed rest – Despite common recommendations for bed rest following dural puncture, this remedy has not been shown to significantly decrease the risk of PDPH [4,74-77].

While of no use for prevention of PDPH, bed rest does decrease the intensity of the headache. (See 'Treatment' below.)

There is a theoretical role for abdominal compression with a tight abdominal binder for prevention and/or treatment of PDPH. The rationale for such treatment is that increased intra-abdominal pressure may be transmitted to the epidural space, may help to seal the dural puncture and decrease cerebrospinal fluid (CSF) leak, and may improve an existing headache

Prophylactic drug therapy – Based on the limited evidence available, we do not recommend administration of prophylactic medications after UDP or LP to prevent PDPH.

In addition, ondansetron may reduce the risk of PDPH. In one randomized trial, 210 women were randomly assigned to receive ondansetron 0.15 mg/kg IV or saline during spinal anesthesia with a 25 gauge Quincke needle for cesarean delivery [84]. PDPH occurred in 5 percent of patients who received ondansetron, compared with 21 percent of patients who did not. Ondansetron may trigger migraine headache in susceptible patients [85]. Further research is needed to elucidate the role of these drugs in PDPH prevention.

In obstetric and general surgical populations, oral caffeine has not been shown to prevent PDPH after dural puncture [86,87].

Epidural blood patch (EBP) is an effective treatment for PDPH, and may also be performed prophylactically before a headache occurs for patients in whom an epidural catheter is placed after an inadvertent dural puncture.

We do not routinely perform prophylactic EBP, since the efficacy is unclear [88-93].

Patients with PDPH typically present with frontal or occipital headache that is worse with sitting or standing, and relieved by lying flat. The headache tends to be worse if it occurs in the first 24 hours, and associated symptoms are more common with severe headaches. In some patients, the symptoms of PDPH are similar to their previously experienced migraine headaches, except that there is an added postural component

Associated symptoms occur in up to 70 percent of patients [24], and may include nausea, neck stiffness, low back pain, vertigo, vision changes (diplopia, blurred vision, or photophobia), dizziness, or auditory disturbances (tinnitus, hearing loss) [42]. In one study of 133 patients who developed PDPH after diagnostic lumbar puncture (LP), neck stiffness was reported in 55.6 percent, shoulder stiffness in 46.6 percent, nausea and vomiting in 33 percent, tinnitus in 22 percent, and photophobia in 23 percent. [4].

Approximately 90 percent of PDPHs occur within 72 hours after a dural puncture, though onset has rarely been reported up to two weeks later [42,98].

Without treatment, most headaches resolve within one week, and one-half resolve by four to five days after dural puncture [ 24,31,99].

Longer duration of PDPH has been associated with the use of a cutting needle for dural puncture compared with a pencil point needle [ 100], dural puncture with the patient in the sitting position compared with lateral decubitus, multiple attempts at dural puncture, and patient history of depression [36].

The diagnosis of PDPH is made clinically by identifying the typical positional headache within 72 hours after a dural puncture. Other causes may need to be excluded if symptoms are atypical

If imaging is performed, findings consistent with PDPH include small ventricles, downward displacement (sagging) of the brain, engorged cerebral venous sinuses, subdural fluid collections, pituitary enlargement, and diffuse meningeal enhancement [2,101,102]. These findings are analogous to those reported in patients with spontaneous intracranial hypotension. (See "Spontaneous intracranial hypotension: Pathophysiology, clinical features, and diagnosis".)

Diagnostic lumbar puncture (LP) should be avoided if possible, due to the risk of worsening an existing PDPH. If performed, however, a low cerebrospinal fluid (CSF) opening pressure or dry tap (indicative of intracranial hypotension) with increased CSF protein and lymphocyte count may be present [103].

The differential diagnosis of headache after dural puncture is broad, as outlined in the table (table 1), but a postural headache in this setting is most likely related to the procedure.

Serious and/or life-threatening etiologies (eg, hemorrhage, thrombosis, vasculopathy, meningitis), which may or may not be related to the dural puncture, must be ruled out in the presence of focal or worsening neurologic deficits. Findings that should prompt further investigation are shown in a table ( table 2).

Subdural hematoma and other forms of intracranial hemorrhage are rare but potentially lethal complications of dural puncture. Intracranial hemorrhage should be suspected in patients with prolonged headache (ie, beyond five to seven days), whose headaches become non-positional, who do not improve or worsen after an epidural blood patch (EBP), or who develop focal neurologic symptoms [104,105]

Other possible causes of postural headache (eg, migraine, headache associated with postural orthostatic tachycardia) may occur coincidentally after dural puncture, and may be excluded based on history, symptoms, and physical examination. Some headaches may improve but are not completely abolished with rest, including in the supine position (eg, migraine)

Mild PDPH — Patients with PDPH who can tolerate an upright position and perform activities of daily living are considered to have mild PDPH; obstetric patients with mild PDPH are able to care for their baby. Patients with mild PDPH may benefit from an initial trial of conservative treatment including bed rest as needed, and a brief course of oral analgesics (see 'Drug therapy' below) and antiemetics as necessary. Vigorous oral and/or intravenous (IV) hydration are also routinely encouraged in postpartum patients as a noninvasive, low-risk therapy [108]

Debilitating PDPH — Patients with PDPH who are unable to tolerate sitting or standing, or are unable to perform activities of daily living (including obstetric patients unable to care for their baby) and whose headache is refractory to a brief trial of conservative measures are considered to have moderate to severe PDPH. These patients should be offered an epidural blood patch (EBP), which may provide permanent symptomatic relief.

Similar to epidural anesthesia, EBP is contraindicated in patients with coagulopathy or on anticoagulation, and in patients with systemic infection or infection at the site for epidural needle placement. Patients with HIV present a theoretical risk for developing central nervous system (CNS) infection after EBP. However, HIV is known to be a neurotropic virus, infecting the CNS in its earliest stages, and no adverse effects have been reported after either neuraxial anesthesia or EBP in HIV-infected patients [118].

Once the epidural space has been identified in this manner, a syringe of autologous venous blood is drawn by a second operator using aseptic technique; the blood is slowly injected through the epidural needle. Typically, headache symptoms will improve within seconds to minutes of the completion of the procedure, although a transient sensation of "fullness" in the back is common

Upon completion of the EBP, the patient is instructed to lie flat (or at a maximum 30 degree angle) for one to two hours with minimal movement. After this, the patient may stand and resume normal activities. It is reasonable to avoid heavy lifting and strenuous activity within the first 24 hours of EBP, although evidence is lacking to support this recommendation. Patients should also be instructed to taper analgesic medications (eg, butalbital-acetaminophen-caffeine) to avoid the possibility of a rebound headache from sudden medication withdrawal

Mechanism of action — The mechanism by which EBP relieves PDPH is unclear, and may be multifactorial. It is thought that the injection of blood directly compresses the thecal sac, thereby increasing lumbar and intracranial cerebrospinal fluid (CSF) pressure. Once the injected blood clots, it may plug the CSF leak and/or initiate an inflammatory reaction that facilitates healing of the puncture site.

Complications — The most common complication of EBP is back pain, which occurs in 25 to 35 percent of patients [113,126,127]. Back pain usually resolves within 48 hours of EBP.

Rare complications include misplacement of blood resulting in spinal subdural hematoma [128] or intrathecal injection and arachnoiditis [126,129]. Other rare complications include infection, subdural abscess [130], facial nerve paralysis [113,131-133], spastic paraparesis, and cauda equina syndrome [134,135].

Drug therapy — A number of drugs have been investigated for the treatment of PDPH in small trials and studies, but none have been proven beneficial for this specific indication. Nevertheless, oral caffeine is a low-risk option for most patients, and caffeine and oral analgesics are options for the symptomatic treatment of PDPH.

Caffeine – Caffeine has commonly been used for treatment of PDPH (sometimes in combination with butalbital and/or acetaminophen), without high-quality supporting evidence [86]. We encourage self-administered oral caffeine in patients who normally drink caffeinated beverages on a daily basis, in order to avoid headache and other symptoms of caffeine withdrawal.

Hearing loss may occur after dural puncture, and has been variably reported in up to 10 to 50 percent of patients after spinal anesthesia, though less than 25 percent of these patients are aware of the deficit [153,154]. It may be unilateral or bilateral, and may occur even in the absence of headache.

Injection of air into the subarachnoid space during placement of neuraxial block may result in acute onset of severe headache and other neurologic signs and symptoms [160,161]. This complication may occur with an UDP if air, rather than saline, is used for loss of resistance to identify the epidural space (see "Epidural and combined spinal-epidural anesthesia: Techniques", section on 'Epidural anesthesia technique'). A pneumocephalus headache can occur within a few seconds if the epidural is placed with the patient in the sitting position, but may be delayed until the patient sits up if the epidural is placed in the lateral decubitus position. Regardless of onset delay, the headache is usually maximal at onset (ie, "thunderclap") [162]

In rare cases, dural puncture has been associated with reversible cerebral vasoconstriction syndrome (RCVS) [177,178] and posterior reversible encephalopathy syndrome (PRES) [179-181], but causation is uncertain; several of these reports involved obstetric patients with possible preeclampsia or eclampsia, which are also associated with RCVS and PRES.

Risk factors – Risk factors for PDPH include patient age (highest among adults 18 to 50 years of age), female gender, pregnancy, possibly prior history of headache, the use of cutting versus pencil point spinal needles, and the use of larger needles. For patients undergoing LP or spinal anesthesia, we recommend performing the procedure with spinal needles that have a pencil point (atraumatic) tip, rather than needles with a sharp cutting tip (Grade 1A).

Prevention – Measures to prevent PDPH after dural puncture (eg, bed rest, placement of a spinal catheter after UDP, medications) have not been proven effective.

Clinical features – PDPH is a postural headache (ie, worse when upright, improved when supine) that usually occurs within 72 hours of dural puncture. In most cases, PDPH resolves within one week, even without treatment. Other causes of headache must be ruled out (table 1).

Treatment – Conservative treatment for patients with mild PDPH includes bed rest and a brief course of oral caffeine and/or oral analgesics. (See 'Mild PDPH' above and 'Drug therapy' above.)

For patients with moderate to severe PDPH that is prolonged (>24 hours) and refractory to conservative measures, we recommend treatment with epidural blood patch (EBP) (Grade 1B).