Focal Paraneoplastic Syndrome associated with small cell carcinoma of the lung

Abstract

Sirs: Paraneoplastic neurological disorders (PND) are rare diseases, which are associated with systemic malignancy but are not caused by direct tumour invasion, infection, metabolic derangements or antineoplastic treatment. They are usually multi-focal but often comprise a number of distinct clinicopathological syndromes [1]. PND are most commonly associated with small cell lung cancer (SCLC). Other tumours include gynaecological cancers, lymphomas (especially Hodgkin’s disease), prostate, testicular, oesophageal and gastric cancers. Here we report a case of a focal paraneoplastic motor neuronopathy in association with SCLC. A 63 year-old right-handed female presented with loss of power and grip in the right hand, which rapidly became severe over a period of a few weeks. Her symptoms continued to worsen slowly for a total period of eight months. She had no pain or sensory loss in the right hand and no symptoms in the left hand or legs. Her neurological symptoms started 20 months after she was diagnosed with SCLC involving the left main bronchus, which was treated successfully with cryotherapy, local radiotherapy and cyclophosphamide, vincristine and etoposide chemotherapy. Her symptoms have been stable for the last 11 years. On examination there was gross wasting in the right hand with profound paralysis of all finger movements with normal upper limb reflexes. Routine blood tests were unremarkable. Antineuronal antibodies at first presentation were positive for the Hu antigen (1/500). CSF analysis showed intrathecal IgG synthesis but was otherwise normal. CT chest and bronchoscopy post-treatment did not show evidence of tumour recurrence. The Gadolinium enhanced MRI scan of the cervicalspine and brachial plexus was also normal. Neurophysiological studies are summarised in Table 1. Electromyography showed partial denervation and reinnervation in the C8, T1 segments. In summary, these results are consistent with a severe C8/T1 and moderate C7 segmental cord lesion which has been unchanged on repeated studies. PND typically but not necessarily precede the presentation of overt malignancy [1]. Here, we have described a case of unusual segmental cord damage at C7 to T1, which developed after the presentation and successful treatment of SCLC. Neurological involvement in this context is more commonly due to either tumour infiltration or a side effect of treatment. However, this is unlikely to be the case in our patient. Firstly, follow-up imaging and bronchoscopy excluded local tumour recurrence. Furthermore, contrast enhanced MR imaging of the cervical spine and brachial plexus did not show evidence of tumour infiltration. Secondly, the development of neuropathy outside the radiotherapy zone suggests that radiotherapy is unlikely to account for this presentation. Finally, vincristine neurotoxicity causes an early-onset dose-related sensorimotor neuropathy, which reverses with discontinuation [2] whereas etoposide causes a sensory-predominant or occasionally autonomic neuropathy [3]. SCLC is the commonest tumour found in association with PND, in the majority of cases with positive anti-neuronal antibodies [1]. Motor neuronopathy has been described mainly in Hodgkin’s disease and a case report of thymoma but not SCLC as a progressive, painless asymmetric weakness beginning in the legs associated with diminished or absent reflexes and lack of corticospinal tract signs [4, 5] which LETTER TO THE EDITORS