A 44 year old female with a severe headache is seen in the Emergency department. She has no prior history of headaches. She has some neck stiffness and prefers the darkened room.

Vital signs:

T  37.3

PR 90/min

BP  130/80

An LP is performed, which shows:Macroscopic appearance: Turbid

Cell count

Leucocytes  855/ul

Polymorphs  1%

Lymphocytes  99%

Erythrocytes  45%

Biochemistry

Protein   0.63  g/l  (0.14-0.45)

Glucose   3.9  mmol/l   (2.8-4.4)

Microscopy    No bacteria seen

Culture  No growth

A culture is continuing

Sample             WCC                  RCC

1                          750                    290

2                          837                    72

3                          855                    45

List 3 possible differentials and your most likely cause

Describe the 4 key abnormalities to help narrow your differential

What other tests would you request to aid in your management?