We investigated neurological findings in 41 prisoners (mean age: 28.6) who participated in a hunger strike between 2000 and 2002. All cases were evaluated using neuropsychological, neuroradiological, and electrophysiological methods. The total duration of fasting ranged from 130 to 324 days (mean 199 days). All cases had 200-600 mg/day thiamine orally for 60-294 days (mean 156) during the hunger strike, and had neurological findings consistent with Wernicke-Korsakoff syndrome. All 41 patients exhibited altered consciousness which lasted from 3 to 31 days. All patients also presented gaze-evoked horizontal nystagmus and truncal ataxia. Paralysis of lateral rectus muscles was found in 14. Amnesia was apparent in all cases. Abnormal nerve conduction study parameters were not found in the patient group, but the amplitude of compound muscle action potential of the median and fibular nerves and sensory nerve action potential amplitude of the sural nerve were lower than the control group, and distal motor latency of the posterior tibial nerve was significantly prolonged as compared with the control group. The latency of visual evoked potential was prolonged in 22 cases. Somatosensory evoked potential (P37) was prolonged but not statistically significant. Our most significant finding was that the effect of hunger was more prominent on the central nervous system than on the neuromuscular system, despite the fact that all patients were taking thiamine. In our opinion, partial recovery of neurological, and neurocognitive signs in prolonged hunger could be a result of permanent neurological injury.

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Intraoral trigeminal afferents elicit EMG activity from the lower facial muscle, orbicularis oris (OR) during swallowing. The upper facial muscles and especially orbicularis oculi (OC) were not previously known to be associated with deglutitional events. Nevertheless, given the large area of intraoral mucosa and teeth innervated by the trigeminal nerve afferents, a connection between OC motoneurons and deglutition may theoretically be expected, which we sought to evaluate in this study. Healthy controls were investigated for the possible synchronization of orbicularis OC and OR muscles during deglutition by the following methods: EMG activities were recorded during voluntary dry, 3-, 10-, 20-ml discrete wet swallowing, and sequential swallowing from a cup, concurrent with respiratory recording. A polygraphic recording was obtained from these muscles to determine whether they were synchronously activated during spontaneous swallowing. The polygraphic recording during spontaneous swallowing demonstrated that the OC and OR muscles were synchronously activated in all subjects. This synchronous activation was less prominent in voluntary discrete swallowing. It is proposed that this might be based on trigemino-solitarii-facial pathways with weaker connection to OC muscles. The synchronization of OC muscle activity with deglutition may be an evolutionary process that should be rudimentary in higher mammals including humans. The swallowing-induced cranial muscle activities could potentially explain some movement disorders, such as craniofacial dystonias.

Swallowing mechanism and neurogenic dysphagia in MS have been rarely studied by electromyographical (EMG) methods. This study aims to evaluate the presence of subclinical dysphagia in patients with mild multiple sclerosis (MS) using electrophysiological methods. A prospective study of 51 patients with relapsing remitting multiple sclerosis and 18 age-matched healthy adults was investigated. We used electromyography to measure the activity of the submental muscles during swallowing. Electrophysiological recordings of patients were obtained during relapse, after relapse, and at any time in remission period. Clinical dysphagia was found in 12% of MS patients, while electrophysiological swallowing abnormalities were encountered in 33% of patients. Subclinical dysphagia was determined in 35% of patients during an MS relapse, in 20% of patients after a relapse, and in 25% of all 51 patients in the remission period based on EMG findings. Duration of swallowing signal of submental muscles in all MS patients was found to be longer than in normal subjects (p = 0.001). During swallowing of 50 ml of sequential water, the compensatory respiratory cycles occurred more often in MS patients than normal subjects, especially during a relapse (p = 0.005). This is the first study investigating swallowing abnormalities and subclinical dysphagia from the electrophysiological aspect in MS patients with mild disability. The electrophysiological tests described in this study are useful to uncover subclinical dysphagia since they have the advantage of being rapid, easy to apply, non-invasive, and without risk for the patients.

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