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 densitiesthe skin both
from the calf and the thigh as well as doinga special test that looks at sweat function bothyour footin 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 involvedtreating the patients, this canbe the first sign of an underlying connective tissue disorder that can then be brought tothe attention of rheumatology and adessed from their standpoint.
Diabetic nephropathyis one of the most common and serious chronic compliions associated with diabetes mellitus. In this tutorial, let'sdiscuss how the mechanisms underlying diabetic nephropathy correlate with the al presentation as well as the treatment of the disease. Now fortunately the mechanisms
underlying diabetic nephropathy, directly correlate withthe al presentation. And the first alfinding of the disease is somewhat paradoxicallyan increased kidney filtration rate orglomerular filtration rate. So, diabetic nephropathy,if you break down the term into nephro and pathy literally means kidneydisease caused by diabetes.
Now typically kidney disease is marked by a decreased filtration rate, so why is it that the first al stage of diabetic nephropathy is that of an increased glomerularfiltration rate? Well recall that the earliest mechanism contributing to diabetic nephropathy is an increased pressurestate, over hereblue.
And this is due to hypertension and efferent vasoconstriction. So let's use a common garden hose to help illustrate how thisincreased pressure state will ultimately resultan increased glomerular filtration rate. So, imagine you have this garden hose and it has a small holein the middle of it.
So first you're gonna open up the spigot and increase the pressureand flow through the hose. Intuitively, this isgoing to increase the rate at which water is leakingfrom the holethe hose. Next, you partially kink off the end of the hose distal to the hole, and once again this isgonna further increase the rate at which waterleaks from the hose.
This is essentially what'soccurringthe glomerulus with the hypertension representing the opening up of the spigot and increasing the pressurebefore the glomerulus,front of the glomerulus, and the efferent vasoconstriction representing the kinking off of the hose, which causes this back pressure.