What is the relationship between vitamin deficiencies and peripheral neuropathy?

From the Guidelines

Vitamin deficiencies, particularly those involving vitamin B12, vitamin B6, and vitamin E, have been associated with peripheral neuropathy.

Key Findings

• Patients presenting with these symptoms may benefit from supplementation with vitamin B12 (1000-2000 mcg orally daily) and vitamin B6 (50-100 mg orally daily) for a duration of 3-6 months 1.
• Vitamin E (400-800 IU orally daily) may also be considered, although its efficacy in alleviating nerve pain is less established 1.
• In some cases, medications such as gabapentin (300-3600 mg orally daily) or pregabalin (150-600 mg orally daily) may be prescribed to manage neuropathic pain symptoms.

Important Considerations

• Vitamin B6 deficiency can cause painful neuropathy and skin lesions due to axonal degeneration of sensory nerve fibers 1.
• Vitamin E deficiency can lead to neurological symptoms such as peripheral neuropathy, muscle weakness, and ataxia 1.
• The optimal dose of vitamin B6 for infants and children is not clear, but excessive supplementation can produce painful neuropathy 1.
• Vitamin E supplementation may be beneficial in patients with fat malabsorption, but large doses can result in over-replacement and exacerbate vitamin K deficiency 1.

From the Research

Vitamin Deficiencies and Peripheral Neuropathy

• Vitamin B6 deficiency and high B6 intake have been described as risk factors for developing peripheral neuropathy (PN) 2
• Low vitamin B6 levels can be seen in patients suffering from peripheral neuropathy of various etiologies, but there is no firm evidence that low B6 levels have a direct causal relationship with PN 2
• Vitamin B12 deficiency is a common cause of megaloblastic anemia, various neuropsychiatric symptoms, and other clinical manifestations, including peripheral neuropathy 3

Relationship Between Vitamin B6 and B12 Deficiencies and Peripheral Neuropathy

• Both vitamin B6 and B12 deficiencies can present with symptoms that appear like polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes (POEMS) syndrome, with painful peripheral neuropathy and sensorimotor dysfunction 4
• Co-existing vitamin B6 and B12 deficiency can be associated with POEMS syndrome, and management of POEMS should include screening of vitamin B6 and B12 to ensure other possible associated causes of symptoms are appropriately treated 4

Diagnosis and Treatment of Vitamin B12 Deficiency

• Vitamin B12 deficiency should be suspected in all patients with unexplained anaemia and/or neurological symptoms, as well as in patients at risk of developing vitamin B12 deficiency such as the elderly and patients with intestinal diseases 5
• Measurement of plasma cobalamins is suggested as the primary analysis followed by measurement of plasma methylmalonic acid in unsettled cases, and plasma holotranscobalamin (holoTC) may be superior to plasma cobalamins 5
• Efficient treatment of vitamin B12 deficiency can be ensured either by injections every 2-3 month or by a daily dose of 1 mg vitamin B12 5

Peripheral Neuropathy Due to Vitamin Deficiencies

• Peripheral neuropathies secondary to vitamin deficiencies are frequently considered but can be difficult to definitively diagnose, and accurate diagnosis is important since these conditions are often treatable and preventable 6
• Length-dependent sensorimotor axonal peripheral neuropathy is the most common presentation of peripheral neuropathy due to vitamin deficiencies, but several examples present in a subacute severe fashion, mimicking Guillain-Barré syndrome 6