The aim of this study is to assess disease activity in patients with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) and Guillain-Barré Syndrome (GBS) using multispectral optoacoustic tomography (MSOT).

The currently available diagnostic procedures for CIDP and GBS do not allow for a clear distinction between remission and active disease and show limitations in sensitivity and specificity during acute diagnostics. This can lead to delayed diagnosis, which is crucial for timely initiation of therapy and, consequently, for a better prognosis. Long-term therapy management is also challenging, as objective parameters for assessing therapeutic success are largely lacking.

MSOT can detect inflammation through the measurement of hemoglobin, a method that our research group has already successfully demonstrated in patients with chronic inflammatory bowel diseases (Knieling, NEJM 2017). The use of MSOT could therefore also be applied to nerve inflammation, allowing for earlier detection of inflammation and nerve damage and contributing to timely treatment of patients.

For nerve imaging, a CE-certified MSOT device from iThera Medical is available at the Pediatric Clinic in Erlangen. In addition, a non-CE-certified device with lower laser power is available, which can be used for bedside examinations.

The arm nerves will be examined in three cohorts, which will be compared with each other and with standard diagnostics (blood tests, electrophysiology, conventional ultrasound).

Each cohort will include ten healthy control subjects, ten patients with CIDP, and ten patients with GBS.

Inclusion Criteria Patient Cohort(s):

• Established diagnosis or suspected CIDP or GBS
• Age: 18 years or older
• Written informed consent provided by participant

Inclusion Criteria Control Cohort:

• Written informed consent provided by participant
• Age: 18 years or older
• No pre-existing conditions that may affect peripheral nerves (e.g., diabetes, traumatic nerve injuries, etc.)

Exclusion Criteria:

• Pregnancy
• Breastfeeding mothers
• Cardiopulmonary instability
• Tattoo in the examination area
• Subcutaneous fat tissue > 3 cm

Patients with Guillain-Barré Syndrome (GBS) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) are recruited from the Department of Neurology. All participants will have a confirmed diagnosis of GBS or CIDP based on established clinical and diagnostic criteria. Recruitment will occur during or following their routine clinical appointments. Eligible patients who provide informed consent will be invited to participate in the study assessments.