Cervical cordotomy for the treatment of oncological pain / Cordotomia cervical para tratamento da dor oncológica: revisâo de literatura

Cordotomy consists in the discontinuation of the spinothalamic tract in the anterolateral quadrant of the spinal cord and aims to reduce the transference of nociceptive information in the dorsal horn of the grey matter of the spinal cord (CPME) for rostral units at the neural axis. Many modalities of cordotomy may be employed: anterior transdiscal between C4-C5; endoscopic infra mastoid tip between C1-C2; percutaneous guided by fluoroscopy infra mastoid tip between C1-C2; percutaneous guided by CT infra mastoid tip between C1-C2; open cordotomy by means of laminectomy. The main indication is for patients in advanced cancer disease with severe neuropathic pain bellow the neck in whom the period of survival due to cancer disease is inferior to 3-4 months. The results for immediate pain relieve ranges from 69% to 100% of the cases, while preoperative Karnofsky scores were 20 and 70, respectively versus post operative Karnofsky scores of 20 and 100 respectively; the difference was determined to be highly significant (p < 0.001).

A cordotomia consiste na discontinuação do trato espinotâmico no quadrante ântero-lateral da medula espinal e visa reduzir a transferência de informação nociceptiva no corno dorsal da substância cinzenta da medula espinal (CPME) para as unidades rostrais no neuroeixo. Muitas modalidades de cordotomia podem ser empregadas: transdiscal anterior entre C4-C5; endoscópica inframastoidea entre C1-C2; Percutânea inframastoidea entre C1-C2 guiada por fluoroscopia; percutânea inframastoidea entre C1-C2 guiada por TC; cordotomia aberta por laminectomia. A principal indicação é para pacientes com câncer avançado com dor neuropática severa abaixo do pescoço nos quais a sobrevida devido ao câncer é inferior a 3-4 meses. Os resultados para alívio imediato da dor varia de 69% a 100% dos casos, enquanto os escores de Karnofsky foram de 20 e 70 no período pré-operatório, para 20 e 100 no período pós-opertaório; a diferença foi estatisticamente significativa (p < 0.001).

Long-Term Potentiation of Excitatory Synaptic Strength in Spinothalamic Tract Neurons of the Rat Spinal Cord

Spinal dorsal horn nociceptive neurons have been shown to undergo long-term synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD). Here, we focused on the spinothalamic tract (STT) neurons that are the main nociceptive neurons projecting from the spinal cord to the thalamus. Optical technique using fluorescent dye has made it possible to identify the STT neurons in the spinal cord. Evoked fast mono-synaptic, excitatory postsynaptic currents (eEPSCs) were measured in the STT neurons. Time-based tetanic stimulation (TBS) was employed to induce long-term potentiation (LTP) in the STT neurons. Coincident stimulation of both pre- and postsynaptic neurons using TBS showed immediate and persistent increase in AMPA receptor-mediated EPSCs. LTP can also be induced by postsynaptic spiking together with pharmacological stimulation using chemical NMDA. TBS-induced LTP observed in STT neurons was blocked by internal BAPTA, or Ni2+, a T-type VOCC blocker. However, LTP was intact in the presence of L-type VOCC blocker. These results suggest that long-term plastic change of STT neurons requires NMDA receptor activation and postsynaptic calcium but is differentially sensitive to T-type VOCCs.

Restricted Spinothalamic Sensory Loss Below Thoracic Dermatomal Level Caused by Pontine Infarction

Cerebral lesions can cause dermatomal sensory deficit. The most commonly reported site is the medulla oblongata due to its well-separated sensory systems. Dermatomal sensory deficit that has developed after pontine infarctions have been reported in several cases, the majority of which involved the medial lemniscus. However, restricted spinothalamic sensory loss has rarely been reported in pontine infarctions. We report herein a patient who presented with dermatomal spinothalamic sensory deficits below the tenth thoracic level after pontine infarction.