Clinicopathologic features of folate-deficiency neuropathy

Isolated optic neuropathy due to folate deficiency with associated iron overload

Isolated optic neuropathy due to folate deficiency is rarely reported. Poor dietary practices, malabsorption, and tobacco/alcohol abuse are usually responsible. We examined a patient with blinding optic neuropathies and isolated folic acid deficiency. Visual acuity recovered after folate replacement. At the same time, serological investigation revealed high ferritin and iron saturation levels with negative genetic markers for haemochromatosis consistent with the diagnosis of iron overload syndrome. There are no reports of blindness associated with iron overload syndrome.

Orphan Peripheral Neuropathies

Objectives:

Generally, neuropathies of peripheral nerves are a frequent condition (prevalence 2–3%) and most frequently due to alcoholism, diabetes, renal insufficiency, malignancy, toxins, or drugs. However, the vast majority of neuropathies has orphan status. This review focuses on the etiology, frequency, diagnosis, and treatment of orphan neuropathies.

Methods:

Literature review

Results:

Rareness of diseases is not uniformly defined but in the US an orphan disease is diagnosed if the prevalence is <1:200000, in Europe if <5:10000. Most acquired and hereditary neuropathies are orphan diseases. Often the causative variant has been reported only in a single patient or family, particularly the ones that are newly detected (e.g. SEPT9, SORD). Among the complex neuropathies (hereditary multisystem disorders with concomitant neuropathies) orphan forms have been reported among mitochondrial disorders (e.g. NARP, MNGIE, SANDO), spinocerebellar ataxias (e.g. TMEM240), hereditary spastic paraplegias (e.g UBAP1), lysosomal storage disease (e.g. Schindler disease), peroxisomal disorders, porphyrias, and other types (e.g. giant axonal neuropathy, Tangier disease). Orphan acquired neuropathies include the metabolic neuropathies (e.g. vitamin-B1, folic acid), toxic neuropathies (e.g. copper, lithium, lead, arsenic, thallium, mercury), infectious neuropathies, immune-mediated (e.g. Bruns-Garland syndrome), and neoplastic/paraneoplastic neuropathies.

Conclusions:

Though orphan neuropathies are rare per definition they constitute the majority of neuropathies and should be considered as some of them are easy to identify and potentially treatable, as clarification of the underlying cause may contribute to the knowledge about etiology and pathophysiology of these conditions, and as the true prevalence may become obvious only if all ever diagnosed cases are reported.

Starvation-induced diplopia and weakness: a case of beriberi and Wernicke's encephalopathy

A 56-year-old teetotaller man with hypertension and gout presented with a week duration of painless worsening diplopia on a background of loss of weight and appetite, generalised lethargy and weakness for 1 year. On examination, he was noted to be hypothermic and tachycardic with generalised muscle wasting. Proximal myopathy, lower limb fasciculations and areflexia, restricted bilateral eye abduction and nystagmus were observed. Blood investigations demonstrated compensated lactic acidosis, acute kidney injury and leucocytosis. A nerve conduction study showed severe length-dependent axonal sensorimotor polyneuropathy. This was a diagnostic dilemma until an MRI brain revealed symmetrical signal abnormality and enhancement in the periaqueductal area indicative of Wernicke's encephalopathy, caused by thiamine deficiency from poor nutrition. Beriberi, also caused by thiamine deficiency, accounted for his tachycardia, polyneuropathy, areflexia, hypothermia and biochemical abnormalities. Both beriberi and Wernicke's encephalopathy are medical emergencies, which were treated with intravenous thiamine to good effect.

Advances in clinical determinants and neurological manifestations of B vitamin deficiency in adults

B vitamin deficiency is a leading cause of neurological impairment and disability throughout the world. Multiple B vitamin deficiencies often coexist, and thus an understanding of the complex relationships between the different biochemical pathways regulated in the brain by these vitamins may facilitate prompter diagnosis and improved treatment. Particular populations at risk for multiple B vitamin deficiencies include the elderly, people with alcoholism, patients with heart failure, patients with recent obesity surgery, and vegetarians/vegans. Recently, new clinical settings that predispose individuals to B vitamin deficiency have been highlighted. Moreover, other data indicate a possible pathogenetic role of subclinical chronic B vitamin deficiency in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In light of these findings, this review examines the clinical manifestations of B vitamin deficiency and the effect of B vitamin deficiency on the adult nervous system. The interrelationships of multiple B vitamin deficiencies are emphasized, along with the clinical phenotypes related to B vitamin deficiencies. Recent advances in the clinical determinants and diagnostic clues of B vitamin deficiency, as well as the suggested therapies for B vitamin disorders, are described.