Lessons Learned from a Migratory Intradural Extramedullary Schwannoma: A Case Report with Review of the Literature

BACKGROUND

Migratory tumors of the spinal cord are rare and can present as a missing tumor intraoperatively. This can lead to unnecessary abandonment of surgery or unnecessary laminectomies.

CASE DESCRIPTION

We present a case of migratory intradural extramedullary tumor of the spine, which was missing intraoperatively. The surgery was abandoned, and on reimaging the tumor was found to have migrated. Here we summarize a review of the literature of such cases and the lessons we learned from our experience, emphasizing the measures to prevent tumor displacement and the importance of intraoperative imaging.

CONCLUSIONS

Migratory schwannoma should be suspected in case of a missing lesion. Intraoperative ultrasonography and myelography use should be definitely considered where facility for intraoperative magnetic resonance imaging is not available. Preventive measures should be taken to avoid tumor migration in all routine cases of intradural extramedullary lesions.

p53 is essential for developmental neuron death as regulated by the TrkA and p75 neurotrophin receptors

Naturally occurring sympathetic neuron death is the result of two apoptotic signaling events: one normally suppressed by NGF/TrkA survival signals, and a second activated by the p75 neurotrophin receptor. Here we demonstrate that the p53 tumor suppressor protein, likely as induced by the MEKK-JNK pathway, is an essential component of both of these apoptotic signaling cascades. In cultured neonatal sympathetic neurons, p53 protein levels are elevated in response to both NGF withdrawal and p75NTR activation. NGF withdrawal also results in elevation of a known p53 target, the apoptotic protein Bax. Functional ablation of p53 using the adenovirus E1B55K protein inhibits neuronal apoptosis as induced by either NGF withdrawal or p75 activation. Direct stimulation of the MEKK-JNK pathway using activated MEKK1 has similar effects; p53 and Bax are increased and the subsequent neuronal apoptosis can be rescued by E1B55K. Expression of p53 in sympathetic neurons indicates that p53 functions downstream of JNK and upstream of Bax. Finally, when p53 levels are reduced or absent in p53+/- or p53-/- mice, naturally occurring sympathetic neuron death is inhibited. Thus, p53 is an essential common component of two receptor-mediated signal transduction cascades that converge on the MEKK-JNK pathway to regulate the developmental death of sympathetic neurons.

Adenovirus-mediated gene transfer of the tumor suppressor, p53, induces apoptosis in postmitotic neurons

Programmed cell death is an ongoing process in both the developing and the mature nervous system. The tumor suppressor gene, p53, can induce apoptosis in a number of different cell types. Recently, the enhanced expression of p53 has been observed during acute neurological disease. To determine whether p53 overexpression could influence neuronal survival, we used a recombinant adenovirus vector carrying wild type p53 to transduce postmitotic neurons. A control consisting of the same adenovirus vector background but carrying the lacZ reporter expression cassette was used to establish working parameters for the effective genetic manipulation of sympathetic neurons. We have found that recombinant adenovirus can be used at titers sufficiently high (10 to 50 multiplicity of infection) to transduce the majority of the neuronal population without perturbing survival, electrophysiological function, or cytoarchitecture. Moreover, we demonstrate that overexpression of wild type p53 is sufficient to induce programmed cell death in neurons. The observation that p53 is capable of inducing apoptosis in postmitotic neurons has major implications for the mechanisms of cell death in the traumatized mature nervous system.