Sudoscan and corneal confocal microscopy (CCM)

This document describes one patient’s experience with Sudoscan and CCM.

  • Sudoscan is a non-invasive nerve damage test that evaluates sweat gland function.
  • CCM is rapid non-invasive ophthalmic imaging technique that identifies corneal nerve fiber damage. It has been used to identify neuropathy in diabetic patients.

The patient (mild vaccine injury followed by Long COVID and EBV)

The patient had mild sequelae after vaccination. These symptoms worsened after a COVID infection and after an EBV infection shortly after vaccination. These are symptoms that the patient previously never had; they started with the vaccine.

Symptoms, as reported by the patient

1- After vaccination


Chest pain (it was maybe neuropathic, l did not even know anything about neurology or neuropathic pain at that moment, so l found it hard to describe it).

Chest spams, heart pounding or palpitations in bradycardia. The bradycardia might simply be because I do a lot of sports, but the important piece is that the palpitations are not happening while there is tachycardia. And l was and l am not nervous when it happens.

Muscle spams (they might be related to the palpitations, the heart is a muscle after all)

Malaise, feeling unwell in general (might be neuropathic pain, l was unsure of what was happening but felt similar to when l have been ill in the past)

A weird leg cramp multiple times when l was in the bed (never had this before)

I went to the hospital and everything was normal at least at the emergency department check (electrocardiagram, basic blood test, etc)

2- After COVID

I got covid (confirmed by three PCRs, most likely Delta variant but the variant is not confirmed) less than a month after the vaccination and l had these acute symptoms:

  • Tiredness
  • Muscle pain
  • Headache
  • Cough (not too strong)
  • Runny nose
  • Insomnia (not too strong)
  • I did not have any major respiratory issue or anything with my smell or taste

I did not go to the hospital, l recovered at home and my acute covid was symptomatic, but similar to a flu

3- After acute COVID sequelae

After acute covid, some of the post vaccination symptoms stayed. The timeline is blurred, but I kept having:

  • Chest spasms following the rhythm of heart pounding (palpitations in bradycardia)
  • Spasms
  • Chest pain
  • Malaise
  • Blood in the stool (this is most likely hemorrhoids, unrelated, but adding everything for the great glory of science)

I had another basic check (electrocardiogram and blood check) and went to a cardiologist to get a cardiac echography (in case that it was myocarditis or pericarditis). It seemed normal and the doctors insisted that they have seen very few people as healthy as l am (bradycardia, l am generally fit, etc).

4- New-onset neurological issues

Suddenly, neurological issues started happening


My hands go numb (often after sleeping, but l never had this before)

Weird feeling that led me to google symptoms and understand the term “dysautonomia”

Weird feeling in my eyes

Weird headaches

Pain behind my right eye

Pain in my neck

This is when l went to the doctor again, got referred to the public/government long covid specialist.

I got new epstein barr antibodies in my blood, which could explain the symptoms, but multiple sclerosis was discarded when they added an electromyogram and an MRI.

Then l went to a private neurologist who did the table tilt test (normal) and the sudoscan and corneal. These two were on the normal range but l was a bit lower than what is completely normal for my demographics.

My symptoms tend to worsen after eating. I never had this, nor did l had any allergy or intolerance. l believe that a new intolerance to some foods might be playing a role. Eating a lot of gluten, for example, makes my hands go numb. I am a very skeptical and science-based person. But, since l have started experiencing this, l think that “neurogluten¨ might be real and happening in my body as part of the sequelae.

Getting access to sudoscan and CCM (in Spain)

Spain provides free basic healthcare to those who contribute to the Spanish social security system.

The path to the test was:

  1. General practitioner.
  2. Long COVID neurologist
  3. Private-pay Long COVID neurologist
  4. Sudoscan
  5. The private Long COVID neurologist told the patient not to worry. However, because the patient wanted to find biomarkers of his illness, the neurologist told the patient to do the second test (CCM).
  6. Specialized ophthalmologist.
  7. Corneal confocal microscopy (CCM) test.

Test results

The test result was on the low end of the normal range suggesting that there may be subclinical nerve damage.

The main point of sharing this is that there are affordable ways to get biomarkers on these sequelae / injuries. This could help the injured in multiple ways right now and in the future:

  1. Get closer to a cure or treatment
  2. Avoid gaslighting
  3. Measure their injury and the potential worsening or improvement
  4. Document officially that you have been injured, for any legal process
  5. Clarify this as a subset of injury/sequelae/long covid, and create a clearer process for the people who are suffering this
  6. Use the past knowledge around small fiber neuropathy to help us with this new pathology

Scientific articles,dysregulation%20as%20a%20common%20mechanism.

For PSSD sufferers, see this post on Reddit:

Alternative to Small Fiber neuropathy skin biopsy: Corneal confocal microscopy

David Healy talks about CCM on his blog RXIsk, he’s trying to get a study going. See PSSD Patients Needed for CCM Investigation | RxISK