D-lactic acidosis presenting as metabolic encephalopathy in a patient with short bowel syndrome

We present a case of D-lactic acidosis presenting as a metabolic encephalopathy secondary to small intestinal bacterial overgrowth. This patient had a known history of short bowel syndrome. Of note, this case required the alteration of treatment to promote a sustained clinical and biochemical improvement. We discuss the pathophysiological mechanisms thought to be involved. We also review the current therapies as well as potential future strategies. This case highlights the importance of the prompt clinical recognition of signs and symptoms as well as the rapid initiation of management strategies to ameliorate this condition.

D-lactic acidosis in humans: systematic literature review

BACKGROUND

D-lactic acidosis is an uncommon and challenging form of metabolic acidosis that may develop in short bowel syndrome. It has been documented exclusively in case reports and small case series.

METHODS

We performed a review of the literature in the National Library of Medicine and Excerpta Medica databases.

RESULTS

We identified 84 original reports published between 1977 and 2017. D-lactic acidosis was observed in 98 individuals ranging in age from 7 months to 86 years with short bowel syndrome. The clinical presentation included Kussmaul breathing, confusion, slurred speech, and gait disturbances. Furthermore, among 99 consecutive patients with short bowel syndrome, 21 reported having episodes with symptoms consistent with D-lactic acidosis. In addition, D-lactic acid might also contribute to acidosis in diabetes mellitus. Finally, abnormally high D-lactic acid was documented after administration or ingestion of large amounts of propylene glycol, as paraneoplastic phenomenon and perhaps also in a so far poorly characterized inherited inborn error of metabolism.

CONCLUSIONS

In humans with short bowel syndrome (or carbohydrate malabsorption), D-lactic acidosis is likely rather common and under-recognized. This condition should be included in the differential diagnosis of unexplained high-gap metabolic acidosis where the anion causing the acidosis is not known. Furthermore, diabetic acidosis might be caused by accumulation of both ketone bodies and D-lactic acid. Finally, there are endogenous sources of D-lactic acid in subjects with propylene glycol intoxication.

Examining clinical similarities between myalgic encephalomyelitis/chronic fatigue syndrome and D-lactic acidosis: a systematic review

BACKGROUND

The pursuit for clarity in diagnostic and treatment pathways for the complex, chronic condition of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) continues. This systematic review raises a novel question to explore possible overlapping aetiology in two distinct conditions. Similar neurocognitive symptoms and evidence of D-lactate producing bacteria in ME/CFS raise questions about shared mechanisms with the acute condition of D-lactic acidosis (D-la).

METHODS

D-la case reports published between 1965 and March 2016 were reviewed for episodes describing both neurological symptoms and high D-lactate levels. Fifty-nine D-la episodes were included in the qualitative synthesis comparing D-la symptoms with ME/CFS diagnostic criteria. A narrative review of D-la mechanisms and relevance for ME/CFS was provided.

RESULTS

The majority of neurological disturbances reported in D-la episodes overlapped with ME/CFS symptoms. Of these, the most frequently reported D-la symptoms were motor disturbances that appear more prominent during severe presentations of ME/CFS. Both patient groups shared a history of gastrointestinal abnormalities and evidence of bacterial dysbiosis, although only preliminary evidence supported the role of lactate-producing bacteria in ME/CFS.

LIMITATIONS

Interpretation of results are constrained by both the breadth of symptoms included in ME/CFS diagnostic criteria and the conservative methodology used for D-la symptom classification. Several pathophysiological mechanisms in ME/CFS were not examined.

CONCLUSIONS

Shared symptomatology and underlying microbiota-gut-brain interactions raise the possibility of a continuum of acute (D-la) versus chronic (ME/CFS) presentations related to D-lactate absorption. Measurement of D-lactate in ME/CFS is needed to effectively evaluate whether subclinical D-lactate levels affect neurological symptoms in this clinical population.

Neurological Complications of Bariatric Surgery

Obesity has attained pandemic proportions, and bariatric surgery is increasingly being employed resulting in turn to more neurological complications which must be recognized and managed. Neurological complications may result from mechanical or inflammatory mechanisms but primarily result from micro-nutritional deficiencies. Vitamin B12, thiamine, and copper constitute the most frequent deficiencies. Neurological complications may occur at reasonably predictable times after bariatric surgery and are associated with the type of surgery used. During the early post-operative period, compressive or stretch peripheral nerve injury, rhabdomyolysis, Wernicke's encephalopathy, and inflammatory polyradiculoneuropathy may occur. Late complications ensue after months to years and include combined system degeneration (vitamin B12 deficiency) and hypocupric myelopathy. Bariatric surgery patients require careful nutritional follow-up with routine monitoring of micronutrients at 6 weeks and 3, 6, and 12 months post-operatively and then annually after surgery and multivitamin supplementation for life. Sustained vigilance for common and rare neurological complications is essential.

The status of probiotics supplementation during pregnancy

Probiotics have been known for their use in medical field for quite a long time. Strong evidences are now available for the use of probiotics in clinical setting. One of the current issues on this topic is the use of probiotics in pregnancy. Recent studies showed that probiotics may be safe and beneficial for prenatal supplementation. In this review, we highlighted several proven use of probiotics supplementation in pregnant women. A few selected strains of probiotics showed promising outcome to prevent preterm labor and preeclampsia, and to reduce atopic eczema but not asthma and wheezing, in offspring of women who had prenatal probiotics supplementation. The mechanism of action responsible for this effect is closely related to the regulation of T cells, although the exact pathways are not defined yet.

Severe propylene glycol toxicity secondary to use of anti-epileptics

Propylene glycol toxicity presenting as high anion gap metabolic acidosis and osmolar gap has been extensively reported in literature, and most of them are secondary to intravenous lorazepam infusion. However, propylene glycol is used as a solvent in a number of medications that are frequently utilized in critical care setting, and hence one should be aware that the toxicity is possible from a variety of medication. Phenobarbital and phenytoin are one of those, and we hereby report a novel case of propylene glycol toxicity secondary to phenobarbital and phenytoin infusion in a patient with refractory status epilepticus. Furthermore, our patient had end-stage renal disease, which we think could have been an important precipitating factor for the toxicity. Because most of the symptoms from propylene glycol toxicity can mimic sepsis-which is very common in critical care unit patients-this life threatening scenario could be easily missed. Regular monitoring of osmolar gap is an easily available intervention in the at risk patients.