Small fiber neuropathy is really an interestingcondition because it consists typically of just burning, numbness, pain of the feet,sometimes the hands later on without necessarily having any abnormalities on your EMG or nerveconduction study. So what I tell patients and actually residents or students who trainunder us is that a normal nerve conduction study does not exclude a neuropathy. And wewill confirm this by doing additional testing, specifically the nervous the the examinationat the bedside asking patients about their symptoms, for example, loss of sensation tocool or or hot temperatures, loss of pain sensation and also doing skin biopsies wherewe look at nerve densities in the skin both
from the calf and the thigh as well as doinga special test that looks at sweat function both in your foot in in the legs as well asthe feet to gauge the level of small fiber nerve damage. Small fiber neuropathy typicallywill progress unless the underlying cause is identified and reversed. Diabetes of coursebeing the most common cause is always screened for. But once the more common causes are excludedand the focus becomes on excluding any underlying secondary disease process but also controllingpain because if patients’ symptoms of pain are generally controlled they tend to do prettywell and really have no other major functional deficits. I’ve really become interested overthe years is how interconnected neurology
and rheumatology are and one thing I oftendo on patients who have unexplained small fiber even autonomic neuropathy is have themsee rheumatology or get evaluated for connective tissue disorders like lupus or Sjogren’s orsarcoid and sometimes even if we are not directly involved in treating the patients, this canbe the first sign of an underlying connective tissue disorder that can then be brought tothe attention of rheumatology and addressed from their standpoint..
Counting Cells with a Hemocytometer
A hemocytometer is a device that is used forcounting cells. It’s a modified microscope slide, containingtwo identical wells, or chambers, into which a small volume of a cell suspension is pipetted. We have already removed 100 ÂµL of our cellsuspension and placed it in a microcentrifuge tube. Dilute the suspension by adding 100 ÂµL ofTrypan blue. Trypan blue is a dye that helps us distinguish between living and dead cells.The dye passes through the membranes of dead cells so they will appear blue under a microscope. Living cells exclude and will appear mostlyclear.
Load both chambers by pipetting the suspensionunder the cover slip. Now place the hemocytometer under the microscope. Each chamber is divided into a grid pattern,consisting of 9 large squares. Each square has the same dimensions and contains10 to the negativefourth power mL of suspension. The rules for counting cells sometimes differfrom labtolab. In our lab, we count cells in the 4 largecorner squares and the center square. Let’s count the cells in the first square. One, Two, Three,
Four, Five, Six, Seven, Eight… So what about the cells that are touchingthe outside boundaries of the square? In our lab we count the cells that touch thetop and left boundaries, and we ignore the cells that touch the right and bottom boundaries. Nine. Ten. We need to count the number of both livingand dead cells. Remember, the dead cells will appear blue.
Occasionally you will see artifacts objectsor debris that appear blurry and don’t have a welldefined shape. This is an example of an artifact. We won’tinclude it in our count. Proper storage, cleaning, and handling ofthe hemocytometer will minimize the number of artifacts. There are 10 viable cells and 1 nonviablecell in the first square. Now, the topright square. There are 9 viable cells and no nonviablecells.
Next let’s count the bottomright square. There are 11 viable cells and no nonviablecells. And now the bottomleft square. There are 10 viable cells and 2 nonviablecells. And finally, let’s count the cells in thecenter square. Sometimes cells will appear as clumps or smallgroups. It may be difficult to determine exactly howmany cells are in a group. The method of counting clumps of cells differsfrom lab to lab, so be sure to follow the
procedure in your lab. We will count this clump as 2 cells. There are 14 viable cells and no nonviablecells in the center square. The total number of viable, or living cellsfrom all 5 squares is 54. The total number of nonviable cells is 3. Now that we have counted our cells, thereare several calculations we need to perform. First, let’s calculate the percentage ofviable cells. Here’s the formula. 54 viable cells, dividedby 57Ã‰the total number of cellsÃ¢