Reflexes come and go; CIDP is forever
Like Julia, my reflexes have come and gone, sometimes within a month, but when I am doing well, I have them. My neurologist has never once suggested that my CIDP went away or was misdiagnosed. Something about that word CHRONIC seems to escape people.
There are sets of diagnostic criteria for CIDP. Reflexes are only part of the clinical presentation. More important are distal and proximal muscle weakness and/or paresthesia and other sensory issues. Nerve conduction velocity is generally the key test, with elevated protein in CSF as a usual adjunct. Some sets of criteria require a sural nerve biopsy, others don’t. If you meet the criteria, you have CIDP (very likely, anyway). If you don’t, you don’t (likely don’t, anyway; nothing is exact in medicine).
Did the neurologist request lab work to test for a B12 deficiency? It is a reasonable to suspect it, as such deficiency has similar symptoms. It is possible you might have both, so if it has been a while, there is no harm. If he did not, in my opinion, he should not be second-guessing the CIDP diagnosis. Even if he did, he should wait for the test results.
Godspeed in dealing with this doctor.