Clinical-immunological and neurophysiological correlations in paraneoplastic polyneuropathy caused by small cell lung cancer

Objective. To study the correlation between the neurological, immunological and neurophysiological signs of paraneoplastic polyneuropathy (PPNP) caused by small cell lung cancer (SCLC), to improve the quality of diagnosis of this pathology.Materials and methods. Clinical, immunological (anti-Hu) and neurophysiological (electromyography (EMG), electroneuromyography (ENMG), somatosensory evoked potentials (SSEP)) examination of 61 patients with PPNP caused by SCLC are presented.Results. It was established that sensory disorders in the limbs are the first and obligate clinical symptoms of PPNP, which precede the initial diagnosis of SCLC in 56% in 3-12 months, characterized by a predominance of a decrease in surface sensitivity in the form of distal hypoesthesia in 70% of cases. The motor form is characterized by an older age (67 years) than the sensory (60 years) and sensorimotor (58.0 years, p <0,05). Motor disorders in the limbs occur in 46% of cases, manifested by mild symmetrical distal paresis of the legs and subclinical damage to the motor nerves of the upper extremities according to the results of ENMG (p <0,001). Detection of anti-Hu in plasma is highly correlated with a significant increase in latency and a decrease in amplitudes component N22 in the conduct of SSEP, which indicates the defeat of the axons of the sensory nerves of the limbs (p <0,05). Changes in amplitude parameters, with preserved speed indicators of nerves according to the results of ENMG indicate an axonal type of lesion (p <0,05), which, in combination with the detection of anti-Hu in plasma, are pathognomonic signs of the paraneoplastic nature of the process.Conclusion. As a result of the study, clinical, immunological and neurophysiological features of various forms of PPNP were identified. The obtained correlations make it possible to diagnose the corresponding type of nerve pathology more accurately and in a timely manner and to suspect the development of oncological disease in time. The revealed changes in the indicators of the N22 component of SSEP can serve as a marker of axonal lesion of peripheral nerves, which with high diagnostic efficiency justifies the expediency of inclusion in the protocol of the ENMG study for verification of additional signs characteristic of PPNP.