Peripheral Neuropathy Due to Cobalamin Deficiency

Area of Science:

• Neurology
• Clinical Medicine
• Biochemistry

Background:

• Vitamin B12 (cobalamin, Cbl) deficiency is linked to various neurological complications.
• Myelopathy, or combined systems disease, is a recognized manifestation of Cbl deficiency.
• The role of peripheral neuropathy as an isolated symptom of Cbl deficiency is debated and not well-characterized.

Purpose of the Study:

• To investigate the prevalence and clinical/electrophysiologic features of peripheral neuropathy in Cbl deficiency.
• To highlight the limitations of standard serum Cbl assays in detecting deficiency.
• To explore the utility of serum metabolites for improved Cbl deficiency diagnosis.

Main Methods:

• Review of existing literature on Cbl deficiency and neurological manifestations.
• Analysis of clinical and electrophysiologic data related to Cbl deficiency peripheral neuropathy.
• Evaluation of diagnostic accuracy of serum Cbl assays versus metabolite testing (methylmalonic acid, homocysteine).

Main Results:

• Peripheral neuropathy may be the sole presenting sign of Cbl deficiency, though its features are not well-defined.
• Standard serum Cbl assays may lack sensitivity in identifying all deficient patients.
• Testing methylmalonic acid and homocysteine can enhance the detection of Cbl deficiency.

Conclusions:

• Neurological complications, including peripheral neuropathy, are significant consequences of Vitamin B12 deficiency.
• Enhanced diagnostic strategies incorporating serum metabolites are recommended for accurate Cbl deficiency identification.
• While parenteral Cbl may not reverse existing deficits, it can halt progression; oral Cbl may also be effective in some cases.