Biomedical subjects

Christopher Ames

Publications and source records attributed to Christopher Ames.

2 recordsLinked to original sources

PubMed2005

Changing stimulation parameters for motor evoked potentials: a case study.

The purpose of this case study was to illustrate the sensitivity of intraoperative motor evoked potentials (MEPs) to stimulation parameters in the absence of any known surgical or anesthetic cause. In this cervical spine surgery, an abrupt, unexplained, unilateral loss of MEPs prompted a search among the stimulation parameter space of voltage, interpulse interval (IPI), pulse duration, and number of pulses, with a surprising result: rather than the usual dependence on voltage and IPI, the upper and lower extremity responses required mutually exclusive combinations of pulse duration and number of pulses (nine pulses, 350 V, 2.5-millisecond IPI, 200 microseconds and four pulses, 220 V, 2.5-millisecond IPI, 500 microseconds, respectively). Parameters far from these sets abolished the responses. The patient's neurologic status was preserved. The authors conclude that exploring alternative stimulation parameters can help to reduce the MEP false-alarm rate by restoring responses without unwarranted changes in the surgical plan.

Adult↗

PubMedDate not supplied

Spinal cord and intradural-extraparenchymal spinal tumors: current best care practices and strategies.

The management of patients with intradural spinal tumors differs in many respects from approaches taken for patients with intracranial tumors. Intramedullary lesions are often completely surrounded by normal spinal cord, displacing vital functional tracts eccentrically. Extramedullary lesions can drastically compress the spinal cord and nerve roots, reducing normal tissue to a ribbon-like consistency. The small amount of normal tissue relative to tumor has implications for surgery and postoperative adjuvant therapy. In addition, operative intervention must take spinal stability into consideration. In this report, we describe the current best care practices and strategies for patients with a diagnosis of spinal astrocytoma, ependymoma, hemangioblastoma, schwannoma, and meningioma. Treatment of patients with intradural tumors of the spinal cord and adjoining structures has changed over the past 20 years. Advances in many disciplines including neuroradiology, neurosurgery, neurooncology, and neuropathology have contributed to expediting diagnosis and improving outcomes.

Humans↗