Diagnosis and Treatment of Pain in Small Fiber Neuropathy, 2011, Hovaguimian & Gibbons

[Sly Saint]

Oldish paper but interesting.
Abstract
Small fiber neuropathy manifests in a variety of different diseases and often results in symptoms of burning pain, shooting pain, allodynia, and hyperesthesia. Diagnosis of small fiber neuropathy is determined primarily by the history and physical exam, but functional neurophysiologic testing and skin biopsy evaluation of intraepidermal nerve fiber density can provide diagnostic confirmation. Management of small fiber neuropathy depends on the underlying etiology with concurrent treatment of associated neuropathic pain. A variety of recent guidelines propose the use of antidepressants, anticonvulsants, opioids, topical therapies, and nonpharmacologic treatments as part of the overall management of neuropathic pain. Unfortunately, little data about the treatment of pain specifically in small fiber neuropathy exist because most studies combine mixed neuropathic pain syndromes in the analysis. Additional studies targeting the treatment of pain in small fiber neuropathy are needed to guide decision making.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086960/

Symptoms of Small Fiber Neuropathy
Symptoms of small fiber neuropathy can vary widely in severity. Many individuals report the gradual onset of distal symptoms that include vague disturbances of sensation in the feet. These symptoms may include the feeling of a wrinkle in a sock that cannot be removed or of small pebbles or sand in the shoe. Others may report a cold-like pain, tingling or a pins and needles sensation. More severe symptoms of small fiber neuropathy may include burning pain that often is persistent, although it may vary in intensity throughout the day. Many patients also report transient electric shock–like pain, usually lasting only seconds, but quite severe and potentially multiple times per day. Many symptoms worsen during periods of rest and at night. In addition to spontaneous pain, many individuals report allodynia and hyperesthesia. Patients with small fiber neuropathy frequently complain that the bedsheets are exquisitely painful, and therefore, wear socks or use “foot tents” to keep the sheets from making physical contact with the feet.

Small nerve fiber neuropathies also may result in autonomic and enteric dysfunction. Patients often do not identify the relationship of these symptoms to their sensory complaints; however, when asked, they may report dry eyes, dry mouth, postural lightheadedness, presyncope, syncope, abnormal sweating, erectile dysfunction, nausea, vomiting, diarrhea, constipation, early satiety, difficulty with urinary frequency, nocturia, and/or voiding [4, 5].

 

[Grigor]

Yup, that's me.

 

[oldtimer]

This is my experience too.

My neuropathy has been described as idiopathic.

The only medication that is tolerable and works for me is codeine + paracetamol (acetominophen) but I can only get a tiny amount of that from my doctor.

So before I get into bed I cool my feet in a bucket of water I keep beside the bed then turn the ceiling fan on to dry them.

Like clockwork, 90 minutes later I wake feeling very ill and physically agitated in every cell of my body. (It's very hard to describe.) This is probably not related to my feet but there's no way I can tolerate the burning of my feet once I've woken up so I dunk them again. After about an hour I eventually get back to sleep.

Very often I wake after another 90 minutes with all the same symptoms. After another dunk and waiting for the other horrible sensations to subside again, I sleep for the rest of the night. This happens all the time.

Cold water is a bit of a miracle for me but a challenge in the middle of winter.

 

[Hoopoe]

The widespread feeling of discomfort, resembling pain but not quite the same, in the whole body is just a manifestation of SFN right?

It triggers the suffering centers in my brain the same way pain does. It's like experiencing pain but without the pain.

 

[Lilas]

A simple question, could the following be related to SFN? :

It's not every day, but recurrently, either when I go to bed or wakes me up at night, my feet burn, like boiling, and very hot to the touch (only my feet). More than unpleasant sensation making it impossible to sleep without cooling them adequately for several minutes (eg with a "magic" bag taken from the freezer).

 

[Ravn]

A simple question, could the following be related to SFN? :

It's not every day, but recurrently, either when I go to bed or wakes me up at night, my feet burn, like boiling, and very hot to the touch (only my feet). More than unpleasant sensation making it impossible to sleep without cooling them adequately for several minutes (eg with a "magic" bag taken from the freezer).

I get this, too. Feet literally red hot as in lobster-red and measurably hot. Highly disagreeable. Suspected (but unconfirmed) erythromelalgia.

It seems to be another mystery condition but there may be a link to SFN.

Erythromelalgia: vasculopathy, neuropathy, or both? A prospective study of vascular and neurophysiologic studies in erythromelalgia

Abstract

Objective: To assess the frequency and type of vascular changes and neurologic abnormalities in patients with erythromelalgia.

Design: Prospective study of patients with no spontaneous symptoms at the time of their visit and with provoked symptoms.

Setting: Tertiary referral center.

Patients: Sixty-seven patients presenting with erythromelalgia at Mayo Clinic, Rochester, Minn, from 1999 through 2001.

Interventions: Testing nerve and vascular function in patients without symptoms present; testing vascular function after provoking symptoms with exercise or by increasing ambient temperature.

Main outcome measures: In patients in whom symptoms could be elicited, vascular function with and without symptoms was assessed by measurement of local skin temperature, laser Doppler flow, and transcutaneous oximetry. Neurologic assessment included electromyography, nerve conduction studies, and autonomic reflex screening (using the quantitative sudomotor axon reflex test, adrenergic function testing, heart rate response to deep breathing, and the Valsalva ratio).

Results: Autonomic reflex screening was performed on 57 (85%) of the 67 patients. Of these 57 patients, 46 (81%) had abnormal quantitative sudomotor axon reflex test results; 14 (25%) had abnormal adrenergic function; and 15 (26%) had abnormal cardiovagal function. Put in another way, results were abnormal for 49 (86%) of the 57 patients who had autonomic reflex screening. Severe sudomotor abnormalities (ie, absent or markedly reduced sweat production) were present in 46 (94%) of these 49 patients; 14 (29%) had abnormal adrenergic function, and 15 (31%) had a cardiovagal abnormality. Electromyography and nerve conduction studies were performed in 24 (36%) of the 67 patients. Of these 24 patients, 14 (58%) had abnormal electromyographic results and 10 (42%) had abnormal nerve conduction study results. Vascular function studies, with and without symptoms present, were performed in 13 of the 67 patients. During symptoms, the mean temperature of the toe skin increased by 7.8 degrees C, and blood flow increased 10.2-fold. Paradoxically, mean transcutaneous oximetry measurements did not change.

Conclusion: This prospective study extends and confirms our previous observation that, in addition to other forms of neuropathy, most patients with erythromelalgia have small-fiber neuropathy.

Davis MD, Sandroni P, Rooke TW, Low PA. Erythromelalgia: vasculopathy, neuropathy, or both? A prospective study of vascular and neurophysiologic studies in erythromelalgia. Arch Dermatol. 2003 Oct;139(10):1337-43. doi: 10.1001/archderm.139.10.1337. PMID: 14568838.
https://pubmed.ncbi.nlm.nih.gov/14568838/

 

[Lilas]

Thank you very much for this information @Ravn , it enlightens me. I didn't know about erythromelalgia. Without doing a self-diagnosis, I'll keep that in mind. This is one of the "weird" symptoms I have with ME. Couldn't tell my GP about it, yet another "mysterious" symptom. Facing suspicion or indifference, no thanks. Since it's not everyday and I manage it, I prefer to endure in silence.

NB: reading on the subject, I realized that it also happens to my cheeks ...

I found a recent and succinct presentation in my language (French), made by a doctor from my Province (see page 16). Strangely, I already take 2 drugs (amitriptyline and pregabalin) which are recommended as a treatment, for my chronic pain and sleep disorder.

https://www.ssvq.org/wp-content/uploads/2020/11/KOENIG-Martial-AcrosyndromesVasculaires_SSVQ2020.pdf