Small Fibers neuropathy Management
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(Part II). Abnormally low secretion of cobalamin in the Part II Schilling test indicates an intestinal cause for the cobalamin malabsorption, such as inflammatory bowel disease. The Part II Schilling test may be repeated, after giving antibiotics or vermacides to exclude bacterial overgrowth ("blind loop syndrome") or fish tapeworm infestation due to diphyllobothrium latum, rare causes of cobalamin deficiency through competition for intraluminal cobalamin. A normal Part I test in a patient with cobalamin deficiency may be observed in total vegetarians. It may also occur in patients with food-cobalamin malabsorption who show normal absorption of crystalline cobalamin but are unable to digest and absorb cobalamin present in food due to achlorhydria. This defect can be identified using a modified Schilling test in which radioactive cobalamin is administered with food (Carmel, 1990). Pyridoxine deficiency will cause elevations in serum homocysteine and cystathionine, and assays are commercially available. Urinary assays for xanthurenic acid and other pyridoxine metabolites
may be performed following tryptophan loading.
Strachan’s syndrome and are polynutritional in origin; therefore, a battery of vitamin deficiencies should be sought, including thiamin, niacin, pyridoxine, and cobalamin. The pathophysiology of post-gastroplasty neuropathy is probably multifactorial, due perhaps to a polynutritional and an endogenous toxin produced as the result of the abnormal anatomy created by the surgical procedure. This toxic hypothesis is supported by the fact that some have reported a resolution of the symptoms following reversal of the surgical procedure whereas nutritional replacement alone does not. Alternatively, there may be a nutritional factor that cannot be replaced adequately until
the procedure has been reversed. Pyridoxine deficiency will cause elevations in serum homocysteine and cystathionine, and assays are commercially available. Urinary assays for xanthurenic acid and other pyridoxine metabolites may be performed following tryptophan loading.
Vitamin E deficiency can be reliably investigated using the serum alpha- tocopherol level. Adult patients without malabsorption and a clinical picture consistent with Friedrich’s ataxia and neuropathy should be investigated for an autosomal recessive defect in the tocopherol transporter
protein gene of chromosome 8. Tocopherol transporter protein incorporates tocopherol into chylomicrons. The serum tocopherol levels in these patients may be in the normal range; however, they respond to high dose supplementation.
Treatment of suspected thiamine deficiency in the setting of post-gastroplasty neuropathy,
Strachan’s syndrome, or Wernicke-Korsakoff syndrome begins with the immediate administration of 100 mg thiamine intravenously followed by 100 mg intramuscularly daily for 3 to 5 days and parenteral multivitamins. Patients are then maintained on 50 mg thiamin orally along with multivitamins daily.
The total body store of cobalamin (B-12) is 2000 to 5000 g, half of that is stored in the liver. The recommended daily allowance is 6 g/day, and the average diet provides 20 g/day. Treatment may begin with sublingual 1000 g of cobalamin for 5 days, then 500 to 1000 g every month.
A daily dose of 1000 g/day orally will yield 10 g of absorbed cobalamin, which exceeds the recommended daily allowance. Sublingual cobalamin 2000 ug/ day is also effective and may be superior to IM injections for some patients (Delpre, 1999). It may be practical to replenish cobalamin stores first using injections of cyanocobalamin for 1 week, and then to maintain patients using a 1000 g daily oral supplement. The effectiveness of treatment, regardless of route, can be confirmed by demonstrating normal serum or urine methylmalonic acid levels three to four weeks after beginning B12 replacement.
The management of post gastroplasty neuropathy begins with a recognition and replacement of vitamin deficiency, particularly thiamine and B12. However, vitamin supplementation alone is rarely successful. A toxic hypothesis is supported by the fact that some have reported a resolution if the symptoms following reversal of the surgical procedure whereas nutritional replacement alone does not.
The management of gluten sensitivity neuropathy is preliminary given its uncertainty. Further study of the efficacy of a gluten free diet in patients with anti-gliadin antibodies and a peripheral neuropathy is warranted
Nutritional and Other Neuropathies Associated with Gastrointestinal Disorders 12/28/02
Laurence J Kinsella, MD, FACP
Chief, Division of Neurology and Neurophysiology
Forest Park Hospital
Associate Professor, Neurology
Saint Louis University