Neurologic complications of lung cancer

Neurological effects of respiratory dysfunction

The respiratory and the nervous systems are closely interconnected and are maintained in a fine balance. Central mechanisms maintain strict control of ventilation due to the high metabolic demands of brain which depends on a continuous supply of oxygenated blood along with glucose. Moreover, brain perfusion is highly sensitive to changes in the partial pressures of carbon dioxide and oxygen in blood, which in turn depend on respiratory function. Ventilatory control is strictly monitored and regulated by the central nervous system through central and peripheral chemoreceptors, baroreceptors, the cardiovascular system, and the autonomic nervous system. Disruption in this delicate control of respiratory function can have subtle to devastating neurological effects as a result of ensuing hypoxia or hypercapnia. In addition, pulmonary circulation receives entire cardiac output and this may act as a conduit to transmit infections and also for metastasis of malignancies to brain resulting in neurological dysfunction. Furthermore, many neurological paraneoplastic syndromes can have underlying lung malignancies resulting in respiratory dysfunction. It is essential to understand the underlying mechanisms and the resulting manifestations in order to prevent and effectively manage the many neurological effects of respiratory dysfunction. This chapter explores the various neurological effects of respiratory dysfunction with focus on their pathophysiology, etiologies, clinical features and long-term neurological sequelae.

Epidural adipose tissue-derived mesenchymal stem cell activation induced by lung cancer cells promotes malignancy and EMT of lung cancer

BACKGROUND

Spinal metastasis is a major challenge in patients with advanced lung cancer, but the mechanisms in the organotropism of metastasis are still unclear. Adipose-derived mesenchymal stem cells (ADSCs) exhibit cancer-promoting properties that influence the tumour microenvironment; however, there is no research on ADSCs from epidural fat thus far.

METHODS

In this study, we isolated and identified ADSCs from epidural adipose tissue for the first time. We examined the activation of epidural ADSCs treated with lung cancer cell-conditioned medium by immunohistochemistry, western blot and qRT-PCR assays. The expression of interleukin (IL)-6 family cytokines in the supernatants of ADSCs were evaluated by enzyme-linked immunosorbent assay. The effects of epidural ADSCs on the growth and invasion of lung cancer cells were evaluated with the CCK-8 and Transwell assays. The expression of signal transducer and activator of transcription 3 (STAT3), matrix metalloprotease and epithelial-mesenchymal transition markers were measured by western blot assays.

RESULTS

Our results showed that ADSCs treated with lung cancer cell-conditioned medium expressed higher levels of the myofibroblast marker α-smooth muscle actin and fibroblast activation protein than ADSCs cultured alone. Then, we found that lung cancer cells induced ADSCs to secrete high levels of IL-6 family cytokines and activate the STAT3 signalling pathway. Moreover, activated epidural ADSCs exhibited the ability to promote lung cancer cell proliferation and invasion by elevating matrix metalloprotease expression and epithelial-mesenchymal transition in cancer cells. Furthermore, blocking IL-6 can counteract the differentiation and tumour-promoting effects of ADSCs.

CONCLUSION

Our results suggest that ADSCs respond to lung cancer cells and are involved in the crosstalk between primary tumours and pre-metastatic niches in epidural fat.

Epithelial-mesenchymal Transition Phenotypes in Vertebral Metastases of Lung Cancer

Vertebral metastases of non-small cell lung cancer (NSCLC) are frequently diagnosed in the metastatic setting and are commonly identified in the thoracic vertebrae in patients. Treatment of NSCLC bone metastases, which are often multiple, is palliative, and the median survival times are 3 to 6 months. We have characterized spontaneous vertebral metastases in a brain metastases model of NSCLC and correlated these findings with epithelial-mesenchymal transition (EMT). Brain metastases were established in athymic nude mice following intracardiac injection of brain-seeking adenocarcinoma NSCLC cells. Thirty-nine percent of mice (14/36) developed spontaneous vertebral metastases, spinal cord compression, and hind-limb paralysis. Vertebral metastases consisted of an adenocarcinoma phenotype with neoplastic epithelial cells arranged in cords or acini and a mesenchymal phenotype with spindloid neoplastic cells arranged in bundles and streams. Quantitative and qualitative immunohistochemical and immunofluorescence assays demonstrated an increase in vimentin expression compared to cytokeratin expression in vertebral metastases. A correlation with EMT was supported by an increase in CD44 in vertebral metastases and parenchymal metastases. These data demonstrate a translational lung cancer metastasis model with spontaneous vertebral metastasis. The mesenchymal and epithelial phenotype of these spontaneous metastases coupled with EMT provide a conduit to improve drug delivery and overall patient survival.

A case of confusion: paraneoplastic encephalomyelitis in an elderly patient suspected of having urinary tract infection-associated delirium

Acute confusion is a common symptom of physical illness in the older patient. In the majority, it is transient and resolves on treatment of precipitants. In a subset of patients, however, neurological decline is progressive, raising concern about a serious underlying cause. We describe the case of a 71-year-old woman who developed progressive cognitive impairment following insertion of a permanent pacemaker for sinoatrial arrests. An initial diagnosis of delirium secondary to a urinary tract infection was suspected; however, the patient became increasingly confused despite treatment. Laboratory tests revealed serum anti-Hu paraneoplastic antibodies, and CT chest identified an occult lung tumour. Cervical lymph node histopathology confirmed a diagnosis of small cell carcinoma of the lung. Although a rare cause of confusion, paraneoplastic encephalomyelitis should be recognised early to allow timely identification and treatment of the associated cancer.

Brachial metastatic plexopathy as the inaugural manifestation of lung cancer: multimodality imaging

Metastatic infiltration of a peripheral plexus, also named metastatic plexopathy (MP), often results in severe pain and muscular weakness. This rather rare event may have a dramatic impact on the quality of life of patients affected by cancer. We hereby report a rare case of painful MP of the left cervicobrachial plexus presenting as the inaugural manifestation of poorly differentiated large-cell lung carcinoma in a 53-year-old patient. This responsible lung carcinoma was fortuitously diagnosed during MRI of the brachial plexus (BP). Complementary cancer staging was completed by contrast-enhanced multidetector CT, 18-fludeoxyglucose–positron emission tomography/CT and colour Doppler ultrasound of the BP. Although MRI remains the gold standard method for imaging the BP, our reported case emphasizes the alternative diagnostic capabilities of contrast-enhanced multidetector CT and ultrasound and confirms the high specificity of 18-fludeoxyglucose–positron emission tomography/CT in distinguishing brachial MP from secondary radiation plexopathy.