Uremic polyneuropathy

A uremic polyneuropathy is a more or less generalized damage of the peripheral nervous system, which occurs as a concomitant disease of uremia triggered by chronic kidney disease (CKD) (Herold 2018).

The aetiopathogenesis is of a complex nature and has not yet been fully clarified.

Toxic effects leading to uremic polyneuropathy are suspected in the form of slowly dialysable toxins, neurotoxic substances and a metabolic disorder.

Vitamin B1 deficiency, hyperparathyroidism and enzymes probably do not play a causal role (Hörl 2004).

Uremic polyneuropathy is aggravated by the following diseases that cause chronic kidney disease:

• diabetes mellitus
• arterial hypertension
• Vasculitis
• Amyloidosis, systemic
• Multiple Myeloma (Basement 2010)

Pathophysiologically, uremic polyneuropathy leads to degenerative damage of the axon, which leads to distension, disintegration and thinning of the axon cylinder. In addition, secondary disintegration of the myelin discs from distal to central (so-called dying back neuropathy) reduces the number of myelinating fibres. However, the pattern of damage is inhomogeneous (Hörl 2004).

This explains why the long pathways in the distal extremities are affected first (Kuhlmann 2015).

Uremic polyneuropathy usually manifests in stage 4 of chronic kidney disease (CKD) (Kasper 2015).

The majority (about 2/3) of patients requiring dialysis suffer from uremic polyneuropathy (Kuhlmann 2015).

Initially, the sensory nerves are affected first, followed by the motor nerves from distal to proximal and from the lower extremities to the upper extremities (Kasper 2015).

The following symptoms may exist:

• Sensitivity disorders
• Dysesthesias
• Loss of the sensation of temperature (especially the sensation of cold)
• Loss of "position sense" (Kuhlmann 2015)
• distally emphasized symmetrical atrophic pareses in advanced stages (Hörl 2004)

Physicalexamination

During the physical examination:

- vibration sensation reduced

- Achilles tendon reflex weakened

and in advanced stages:

- muscular atrophy

- Myoclonia

- Paralysis

(Basement 2010)

The characteristics of peripheral neuropathy can be detected electrophysiologically and histologically before the onset of clinical manifestation (Kasper 2015).

Electrophysiological examination: The following statements can be made during the electrophysiological examination:

- Reduced nerve conduction velocity (this is already detectable in the sensitive sural nerve at an early stage; it decreases parallel to creatine clearance [Keller 2010])

- Type of damage (axonal, demyelinating)

- Distribution type of damage (distal / proximal, symmetrical / asymmetrical)

- Extent of muscle damage

(hay 2019)

Histological examination: Demyelination can be detected (Heuß 2019)

The occurrence of uremic polyneuropathy is an indication for dialysis or for optimizing the dialysis dose (Kasper 2015).

Additionally, one can try to treat neuropathic pain with:

• tricyclic antidepressants such as amitriptyline
• or antiepileptic drugs such as carbamazepine(gabapentin is contraindicated in chronic kidney disease) (Kuhlmann 2015)

Due to the early start of dialysis treatment, the symptoms are usually only subclinical (Hörl 2004).

After a kidney transplantation, the symptoms initially improve severely, but further improvement occurs only gradually (Keller 2010).

1. Herold G et al (2018) Internal Medicine. Herold Publishing House 642
2. Heuß D et al (2019) Diagnosis of polyneuropathy. Guidelines of the DGN
3. Hörl W H et al (2004) Dialysis procedures in clinic and practice: Technology and clinic. Georg Thieme Publishing House 435 - 436
4. Kasper D L et al (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education 2426
5. Kasper D L et al (2015) Harrison's Internal Medicine. Georg Thieme Publisher 2234
6. Keller C K et al (2010) Practice of nephrology. Springer publishing house
7. Kuhlmann U et al (2015) Nephrology: Pathophysiology - Clinic - Kidney replacement procedure. Thieme Publishing House 437