Pitfalls in the diagnostic evaluation of subacute combined degeneration

Serum copper decrease and cerebellar atrophy in patients with nitrous oxide-induced subacute combined degeneration: two cases report

Background

Subacute combined degeneration (SCD) is a neurological complication commonly associated with vitamin B₁₂ deficiency. It can result from nitrous oxide (N₂O) abuse and cause neuropsychiatric symptoms. However, there has been no literature regarding alterations of serum copper and cerebellum in SCD patients.

Case presentation

We reported two cases of young SCD patients with histories of N₂O abuse. In these cases, elevated homocysteine, macrocytic anemia, spinal cord abnormalities, and peripheral nerve injuries were detected. In addition, decreased serum copper level and cerebellar atrophy were reported for the first time. The patients’ symptoms improved after withdrawal of N₂O exposure and vitamin B₁₂ supplements.

Conclusion

We reported two SCD cases with serum copper alteration and cerebellar atrophy after N₂O abuse for the first time. These might be crucial complements to the diagnosis of SCD.

A Brief Review on Vitamin B12 Deficiency Looking at Some Case Study Reports in Adults

In the era of evidence-based medicine, the randomized clinical trial corresponds to the top step in the qualitative scale of the evidence available in the literature, while small series of cases or the description of individual cases occupy the last place. However, the latter represent an important part of clinical practice and have significantly influenced the evolution of medicine, contributing significantly to the advancement of scientific knowledge. Vitamin B₁₂ deficiency shares several common symptoms that affect several tissues and organs with health aliments, so its diagnosis could be unobvious for the broad array of its effects and investigation methods used. In this review, we focused our attention on some case reports related to the vitamin B₁₂ deficiency associated to anemia, neurologic disorders, and hyperhomocysteinemia. B₁₂ deficiency reversal is simply achieved by prompt therapy, even though it is not the same for several disorders.

Is serum vitamin B12 decrease a necessity for the diagnosis of subacute combined degeneration?: A meta-analysis

BACKGROUND

To determine the prevalence of subacute combined degeneration (SCD) patients with normal or elevated serum vitamin B12 level and to identify clinical characteristics of these patients.

METHODS

We searched PubMed, EMBASE, and Cochrane library, without language restriction up to June 2019 and included studies with SCD patients who were diagnosed with normal or elevated serum vitamin B12 levels. Meta-analysis was performed to estimate the prevalence of SCD in patients with normal or elevated serum vitamin B12 levels and compare the differences of clinical data between patients with low and no-low serum vitamin B12 level.

RESULTS

Six studies were included in our analysis, with a total number of 181 patients involved. The pooled proportion in patients with no-low serum vitamin B12 level was 31.0% (95% confidence interval [CI]: 22.5-40.8). There was no significant difference in the level of hemoglobin (Mean difference (MD): -3.05, 95% CI: -12.42 to 6.33. P = 0.52) and erythrocyte mean corpuscular volume (MD: -2.37, 95% CI: -11.17 to 6.43, P = 0.60) between SCD patients with no-low and those with low serum vitamin B12 levels. The meta-analysis showed that the functional disability rating scale on admission in patients with low serum vitamin B12 level was no worse than that with normal or elevated serum vitamin B12 level (MD: 0.29, 95% CI: -0.58 to 1.16, P = 0.51).

CONCLUSION

Decreased level of serum vitamin B12 may not be a necessity for the diagnosis of SCD. Approximately one third of the SCD patients have normal or elevated serum vitamin B12 level. No differences were found in clinical severity between patients with normal or elevated serum vitamin B12 level and those with low level of serum vitamin B12 on admission.

Serum methylmalonic acid correlates with neuropathic pain in idiopathic Parkinson's disease

Recent studies have shown a relatively higher prevalence of peripheral neuropathy in idiopathic Parkinson's disease (IPD). The hypothesis is that prolonged levodopa exposure causes vitamin B12 deficiency, which leads to peripheral neuropathy. The aim of our study was to find the relationship between vitamin B12 and its precursor methylmalonic acid (MMA) in IPD patients with neuropathic pain. We performed a cross-sectional study by enrolling consecutive 43 patients who were clinically tested positive for F-18 FP-CIT PET and 15 patients were diagnosed with peripheral neuropathy according to the Toronto clinical scoring system (TCSS). The severity of neuropathic pain was evaluated using total neuropathy scale, revised (TNSr), and Korean Neuropathic Pain Questionnaire (KNPQ). The correlations between age, IPD duration, levodopa equivalent dose (LED), UPDRS III, vitamin B12, MMA, and homocysteine levels were assessed. The prevalence rate of peripheral neuropathy in IPD patients was 35%. Among the serums assessed, MMA levels showed a positive correlation to TNSr and KNPQ in the IPD patients with peripheral neuropathy (TNSr r = 0.882, p < 0.001, KNPQ r = 0.710, p = 0.004), while Vitamin B12 and homocysteine showed no statistically significant correlation. Our study showed a prevalence of peripheral neuropathy in 35% of Korean IPD patients. The serum MMA positively correlated with the severity of neuropathic pain and this can be used as a useful marker in assessment of peripheral neuropathy in Parkinson's disease.