Study Pinpoints Potential Risk Factors for Peripheral Nervous System Conditions in SLE

High blood pressure and a skin condition characterized by a netlike pattern of reddish-blue skin discoloration — livedo reticularis — may be risk factors for peripheral nervous system manifestations in systemic lupus erythematosus (SLE), a retrospective study suggests.

The study, “Peripheral nervous system involvement in systemic lupus erythematosus: a retrospective study on prevalence, associated factors and outcome,” was published in Lupus.

The nervous system is made up of two components: the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which encompasses nerves and neurons that reside or extend outside the brain and spinal cord to innervate organs, muscles, blood vessels, and glands.

SLE can affect both the central and peripheral nervous systems, and research suggests that disorders of the PNS in SLE are a major cause of morbidity.

Nonetheless, “to date, little is known about the actual prevalence of PNS involvement in SLE (PNSLE) or the demographic and specific immunological factors associated with this type of involvement,” investigators said.

Using 14 years (2000-2014) of patient records, investigators from the University of Ferrara in Italy set out to determine the prevalence of peripheral nervous system involvement in 1,224 SLE patients. Researchers made sure to distinguish between manifestations caused by SLE from non-SLE ones.

Eighty-five (6.9%, mostly women) of the 1,224 patients had experienced at least one peripheral nervous system manifestation. A total of 97 PNS events were reported.

“In two cases, the event preceded the diagnosis of SLE, and in 26 patients, PNS involvement appeared at the onset of the disease, while in the remaining 57 patients, PNS involvement appeared more than three months after the diagnosis of SLE,” researchers reported.

Peripheral nervous system manifestations of 61 out of the 85 patients were linked to SLE.

Polyneuropathy, also known as peripheral neuropathy, was the most common PNS event observed (38 cases, 39.2%), followed by cranial neuropathy (30 cases, 30.9%).

Polyneuropathy refers to damage of the peripheral nerves and is the most common type of disorder of the peripheral nervous system in adults, specifically in the elderly. In contrast, cranial neuropathy occurs when there is damage in the nerves that arise from the brain and brainstem, which can affect the ability to move or feel the face.

Age of SLE onset was significantly higher in patients who had peripheral nervous system complaints (mean age 45.9 years), in comparison to sex- and SLE duration-matched SLE patients without central or peripheral manifestations (control group, mean age 37.1 years).

PNS SLE subjects were also likely to have severe disease, as measured by the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index.

Regarding generic risk factors in the PNS sample, smoking habit, diabetes, and high blood pressure were more often reported, but livedo reticularis was the only specific one to be correlated with PNS involvement in SLE.

PNS SLE patients also had a higher chance of having both chronically high blood pressure (hypertension) and livedo reticularis at the same time.

Patients were treated following the recommendations of the European League against Rheumatism (EULAR) for the management of neuropsychiatric lupus.

Cranial neuropathies were managed with corticosteroids and immunosuppressants, and neurotrophic and antipsychotic drugs were used in polyneuropathies.

Investigators reported improvements in 63.6% of polyneuropathy cases linked to SLE, whereas 18.2% of SLE-related polyneuropathy cases worsened over time.

All non-SLE cranial neuropathy cases improved and only one patient’s SLE-linked peripheral nervous system clinical status worsened.

Although the prevalence of PNS involvement in this study sample was similar to previous research, there’s no doubt that peripheral nervous system manifestations are a potential complication of SLE.

The Italian team concluded that “careful neurological assessment should therefore be included in the diagnostic workup of patients with systemic lupus erythematosus, especially in those with later onset and greater damage and disease activity.”