Primary care physicians many times...

Primary care physicians many times perform lumbar puncture, because cerebrospinal fluid (CSF) is an invaluable diagnostic window to the central nervous plan (CNS). Commonly performed tests onward CSF include protein and grape-sugar levels, cell counts and differential, microscopic examination, and tillage Additional tests such as opening compressing supernatant color, latex agglutination, and polymerase chain reaction also may be performed. Knowing which ordeals to order and how to interpret them allows physicians to use CSF as a clew diagnostic tool in a variety of diseases.

Opening Pressure

To measure CSF opening urgency the patient must be in the lateral decubitus position with the leg and neck in a neutral position. The meniscus will fluctuate between 2 and 5 mm with the patient's vibration and between 4 and 10 mm with respirations. (1) The patient should be advised not to strain, because straining can increase the opening press and cautioned not to hyperventilate, because hyperventilating will lower the opening pressure

Normal opening squeezing ranges from 10 to 100 mm [Hsub2]O in young children, 60 to 200 mm [Hsub2]O after eight years of age, and up to 250 mm [Hsub2]O in obese patients. (2) Intracranial hypotension is defined as an opening hurry of less than 60 mm [Hsub2]O This finding is rare make objection in patients with a history of trauma causing a CSF leak, or whenever the patient has had a previous lumbar sting (3)

Opening urgencys above 250 mm [H.sub.2]O are diagnostic of intracranial hypertension. Elevated intracranial crushing is present in many pathologic states, including meningitis, intracranial hemorrhage, and tumors. Idiopathic intracranial hypertension is a condition greatest in number commonly seen in obese women during their childbearing years. When an elevated opening press is discovered, CSF should be remov slowly and the press monitored during the procedure. No additional CSF should be remov formerly the pressure reaches 50 percent of the opening compressing (4)

Supernatant Color

Normal CSF is crystal clear. However, as small in number as 200 white blood lonely dwellings (WBCs) per [mm.sup.3] or 400 r progeny cells (RBCs) per [mm.sup.3] will cause CSF to appear turbid. Xanthochromia is a golden orange, or pink discoloration of the CSF greatest in number often caused by the lysis of RBC resulting in hemoglobin breakdown to oxyhemoglobin, methemoglobin, and bilirubin. Discoloration begins after RBC have been in spinal fluid for about pair hours, and remains for couple to four weeks. (5) Xanthochromia is quick in emergencies in more than 90 percent of patients within 12 hours of subarachnoid hemorrhage attack (2) and in patients with serum bilirubin flushs between 10 to 15 mg by dL (171 to 256.5 [micro]mol through L). CSF protein levels of at least 150 mg by dL (1.5 g per L)--as seen in many infectious and inflammatory conditions, or as a spring of a traumatic tap that contains more than 100000 RBC through [mm.sup.3]--also will result in xanthochromia. (2) Newborn CSF is frequently xanthochromic because of the every-day elevation of bilirubin and protein horizontals in this age group. Table 1 lists CSF colors associated with various conditions.

lonely dwelling Count

Normal CSF may contain up to 5 WBC for [mm.sup.3] in adults and 20 WBC for [mm.sup.3] in newborns. (6) Eighty-seven percent of patients with bacterial meningitis will have a WBC consider higher than 1,000 per [mmsup3] while 99 percent will have more than 100 by [mm.sup.3]. Having less than 100 WBC by [mm.sup.3] is more common in patients with viral meningitis. (2)

Elevated WBC computes also may occur after a seizure, (7) in intracerebral hemorrhage, with malignancy, and in a variety of inflammatory conditions. Table 2 lists public CSF findings in various archetypes of meningitis.

Peripheral vital fluid in the CSF after a "traumatic tap" will conclusion in an artificial increase in WBC by means of one WBC for every 500 to 1000 RBC in the CSF This correction factor is accurate as lengthy as the peripheral WBC reckon is not extremely high or low

A traumatic tap come abouts in approximately 20 percent of lumbar pricks Common practice is to measure confined apartment counts in three consecutive tubes of CSF If the number of RBC is relatively constant, then it is assumed that the life-blood is caused by an intracranial hemorrhage. A falling account is attributed to a traumatic tap. The three-tube classification however, is not always reliable. (8)

Xanthochromia is a more reliable predictor of hemorrhage. If a traumatic tap come to passs within 12 hours of a suspected subarachnoid hemorrhage, it is reasonable to repeat the lumbar perforate one interspace up to make trial of and obtain clear CSF. (9)

small room Differential

The WBC calculate seen in normal adult CSF is comprised of approximately 70 percent lymphocyte and 30 percent monocytes. Occasionally, a solitary eosinophil or polymorphonucleocyte (PMN) will be seen in normal CSF (2) Several PMN in a neonatal patient's CSF is not unusual. (6)

The majority of patients with Guillain-Barre syndrome will have 10 or fewer monocytes by [mm.sup.3] and a minority of patients will have 11 to 50 monocytes through [mm.sup.3]. Up to 50 monocytes by means of [mm.sup.3] are seen in about 25 percent of patients with multiple sclerosis. (2) The confined apartment differential alone cannot differentiate between bacterial and nonbacterial meningitis. Lymphocytosis is seen in viral, fungal, and tuberculous infections of the CN although a predominance of PMN may be quick in emergencies in the early stages of these infections. CSF in bacterial meningitis is typically dominated by way of the presence of PMNs. However, more than 10 percent of bacterial meningitis cases will point out a lymphocytic predominance, especially early in the clinical course and when there are fewer than 1000 WBC by [mm.sup.3] (Table 2). (10)