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  1. What is the role of brain CAT scan imaging prior to lumbar puncture?

  2. What is the best patient positioning to perform lumbar puncture?

  3. What are important factors to consider in preventing post dural puncture headache?

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Case 114-1

A 54-year-old morbidly obese man described the “worst headache” of his life and mild photophobia to an examining physician. His medical history did not reveal any risk factors for increased intracranial pressure (age > 60 years, immune-compromised state, presence of CNS disease, new onset of seizure, confusion, or symptoms suggestive of focal neurologic abnormalities). His physical examination was notable for a temperature of 100.5°F, alert and appropriate mental status, supple neck examination, and the absence of focal neurologic findings (hemiparesis, aphasia, visual field cuts, or cranial nerve palsies). His physician ordered immediate empiric antibiotics prior to a head CT scan. A proceduralist performed an ocular ultrasound which demonstrated an optic nerve sheath diameter (ONSD) of 5.8 mm in the left eye and 6.0 mm in the right eye. Because the ONSD was elevated, a CT scan of his brain without contrast was obtained and reported no acute bleed, midline shift, or mass effect.

Using ultrasound guidance and a 22 g × 124 mm Gertie Marx needle, a lumbar puncture was performed to rule out subarachnoid hemorrhage and meningitis. Because of his girth, the patient sat upright during the procedure. After return of fluid was noted, the proceduralist replaced the stylet and gently lowered the patient to the left lateral position. The proceduralist documented an opening pressure of 380 mm Hg with the patient relaxed and breathing comfortably and the presence of respiratory variation in the manometer. He removed 40 cc of colorless CSF for diagnostic evaluation and recorded a closing pressure of 170 mm Hg. The WBC count was 300 with predominant neutrophils and the RBC count was zero. The results of the spinal tap (300 WBCs/hpf with predominant neutrophils and zero RBCs/hpf) were consistent with the diagnosis of acute meningitis and the patient was admitted for continued intravenous antibiotic therapy.

Lumbar puncture (LP) is a procedure to sample the cerebrospinal fluid (CSF) surrounding the brain and spinal cord. It can be performed on an inpatient or outpatient basis using local anesthesia. Individuals trained to perform this procedure generally include hospitalists and other internists, proceduralists, emergency physicians, pediatricians, neurologists, and radiologists. It has been estimated that 400,000 diagnostic lumbar punctures are performed in the United States annually with charges estimated between $2000 to $3000 for each uncomplicated procedure.

The majority of the CSF is in the subarachnoid space, where the arachnoid membranes bridge the sulci of the brain, in the basal cisterns and around the spinal cord. CSF moves within the ventricles and subarachnoid spaces under the influence of hydrostatic pressure generated by the production of CSF by the choroid plexus of the lateral third and fourth ventricles. The volume of CSF in humans ...

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