Lumbar puncture and the risk of herniation: when should we first perform CT?

Abstract

Death following lumbar puncture (LP) is feared by physicians. Many opinions are found in literature on the question whether computed cranial tomography (CT) should be performed before LP, to prevent herniation. These opinions are mainly based on retrospective studies and pathophysiological reasoning. In this review the difficulties in the decision whether we should perform CT before LP are discussed. It is explained that the concept of "raised intracranial pressure" is confusing, and that the less ambiguous terms "brain shift" and "raised CSF pressure" should be used instead. Brain shift is a contraindication to LP, whether CSF pressure is raised or not, and whether papilloedema is present or not. Subsequently, recommendations are offered for indications to perform CT before LP, grouped according to the safety and clinical utility of LP.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

“…When this is suspected, rapid bedside evaluation and head CT are indicated. Several studies in patients with meningitis have suggested that CT should precede lumbar puncture in patients with signs such as optic disc edema, new seizures, or severe impairment of consciousness (see Table 10 in [65] for a succinct summary of contraindications to lumbar puncture) [134][135][136]. In practice, we find that most patients have had an initial CT scan in the emergency department prior to neurological evaluation.…”

Clinical Reasoning: A 44-year-old woman with headache followed by sudden neurologic decline

“…1,5 Seizures, focal neurologic deficits, papilledema, and altered consciousness may predict increased ICP in the setting of normal-appearing radiologic images in acute meningitis. 1,6 While some experts propose that these clinical signs warrant performance of CT prior to LP, 7 others suggest that their presence should lead to deferment of LP. 1 The potential diagnostic uncertainty if LP is deferred may be mitigated by laboratory testing such as blood cultures (positive in 40%-50% of patients with meningococcal meningitis and 80%-90% with pneumococcal or Hemophilus meningitis).…”

Neuro-Intensive Care of Patients with Acute CNS Infections

“…Lumbar puncture in patients with bacterial meningitis carries a risk of brain herniation [18,19]. Patients with space-occupying lesions in the CNS (e.g., brain abscess, subdural empyema, subdural hemorrhage, brain tumor, or necrotic temporal lobe in herpes simplex encephalitis) may present with symptoms that appear identical to bacterial meningitis, and lumbar puncture may be complicated by herniation [18,20].…”

“…Patients with space-occupying lesions in the CNS (e.g., brain abscess, subdural empyema, subdural hemorrhage, brain tumor, or necrotic temporal lobe in herpes simplex encephalitis) may present with symptoms that appear identical to bacterial meningitis, and lumbar puncture may be complicated by herniation [18,20]. Emergent neuroimaging to evaluate for a CNS space-occupying lesion should be completed prior to lumbar puncture in patients who have new onset seizures, focal neurologic signs on examination, a history of a spaceoccupying CNS lesion, an immunocompromised state, signs of increased intracranial pressure, or moderate-tosevere impairment of consciousness [18,19,21]. However, empiric treatment for bacterial meningitis should not be delayed while awaiting neuroimaging prior to lumbar puncture.…”