**5.2 Neurological complications**

Neurological complications may occur after BS. They have attracted attention because of their diversity, complexity and potentially devastating effects [46]. Different patterns of complications can be observed according to the time of presentation. For instance, at an early stage, immediate peripherical nerve injury, Wernicke's encephalopathy, and polyradiculoneuropathy are the most frequent. Late complications may appear after years, and include optic neuropathy, myelopathy, and peripherical neuropathy [47]. The prevalence of neurological events after BS is difficult to determine. A cross-sectional study reported a rate of 3% among 451 patients who underwent BS [48]. Axonal polyneuropathy was the most frequent neurological complication, but cases of Wernicke syndrome, vitamin B12 deficiency, Guillain-Barre syndrome and copper deficiency were also identified [44]. The majority of patients (93.3%) had full recovery from the neurological signs and symptoms [49]. In another retrospective study involving 592 post LSG patients, only 1.18% were found to have neurological complications [50]. In this cohort, all the patients had decrease in oral intake and rapid weight loss, with a mean weight loss of 35 kg three months after LSG suggesting that this could be the predisposing cause [50]. All patients were treated for neuropathy secondary to vitamin B1 deficiency and had significant improvement and/or resolution of their symptoms. [50]. A recent study showed that among 61 patients post RYGB and LAGB, 11.4% developed some signs of polyneuropathy, that eventually disappeared at 24 months. The most common manifestations were paresthesia and muscle weakness [51]. The majority of neurological complications post BS is attributed to vitamin and micronutrient deficiencies such as vitamins B12, B6, E, thiamine, folate and copper [23, 47, 46]. It is imperative to note that failure of diagnosis and the delay in the management of these complications can lead to irreversible neurological deficits. However, many of these complications can be prevented with regular follow-ups, routine screening of micronutrients, and nutritional supplementation where a deficiency is identified.
