SFN do I really need more testing?

HI! I have been diagnosed with SFN, I have had 4 MRI´s, a punch biopsy, extensive blood tests (tested for lupus, aids, hepatitis, glucose tolerance, thyroids, ANA, and so on, they all came out ok).
Im taking tramadol for pain, it takes the pain away but not the numbness, tingling.
My Doctor recommended that the QSART test and a spinal tap, Is it absolutely necesary?
Im scared of the spinal tap, im reading so many scary stories!

[dr_simran]

Hello Dear,
The quantitative sudomotor axon reflex test (QSART) is used to assess the small nerve fibers, which are linked to the sweat glands
QSART is used to diagnose:
Painful, small fiber neuropathy when nerve conduction test results are normal
Headache  may occur after spinal tap. Drinking fluids, especially caffeine products such as tea, coffee, and cola can also help to reduce headaches.
Your puncture site may be sore for 1-2 days.
You should go for the tests to come to a definitive diagnosis.
Refer http://www.emedicinehealth.com/spinal_tap/page5_em.htm
Best

[se77]

Thank you very much for your kind response.