Focused ultrasound (FUS) has been under investigation for neurosurgical applications since the 1940s. Early experiments demonstrated ultrasound as an effective tool for the creation of intracranial lesions; however, they were limited by the need for craniotomy to avoid trajectory damage and wave distortion by the skull, and they also lacked effective techniques for monitoring. Since then, the development and hemispheric distribution of phased arrays has resolved the issue of the skull and allowed for a completely transcranial procedure. Similarly, advances in MR technology have allowed for the real-time guidance of FUS procedures using MR thermometry. MR-guided FUS (MRgFUS) has primarily been investigated for its thermal lesioning capabilities and was recently approved for use in essential tremor. In this capacity, the use of MRgFUS is being investigated for other ablative indications in functional neurosurgery and neurooncology. Other applications of MRgFUS that are under active investigation include opening of the blood-brain barrier to facilitate delivery of therapeutic agents, neuromodulation, and thrombolysis. These recent advances suggest a promising future for MRgFUS as a viable and noninvasive neurosurgical tool, with strong potential for yet-unrealized applications.
Maya Harary, David J. Segar, Kevin T. Huang, Ian J. Tafel, Pablo A. Valdes and G. Rees Cosgrove
Asad M. Lak, Amina Rahimi, Abdullah M. Abunimer, Ian Tafel, Sharmila Devi, Akash Premkumar, Fidelia Ida, Yi Lu, John H. Chi, Shyam Tanguturi, Michael W. Groff and Hasan A. Zaidi
Metastatic spinal cord compression (MSCC) imposes significant impairment on patient quality of life and often requires immediate surgical intervention. In this study the authors sought to estimate the impact of surgical intervention on patient quality of life in the form of mean quality-adjusted life years (QALY) gained and identify factors associated with positive outcomes.
The authors performed a retrospective chart review and collected data for patients who had neurological symptoms resulting from radiologically and histologically confirmed MSCC and were treated with surgical decompression during the last 12 years.
A total of 151 patients were included in this study (mean age 60.4 years, 57.6% males). The 5 most common metastatic tumor types were lung, multiple myeloma, renal, breast, and prostate cancer. The majority of patients had radioresistant tumors (82.7%) and had an active primary site at presentation (67.5%). The median time from tumor diagnosis to cord compression was 12 months and the median time from identification of cord compression to death was 4 months. Preoperative presenting symptoms included motor weakness (70.8%), pain (70.1%), sensory disturbances (47.6%), and bowel or bladder disturbance (31.1%). The median estimated blood loss was 500 mL and the average length of hospital stay was 10.3 days. About 18% of patients had postoperative complications and the mean follow-up was 7 months. The mean pre- and postoperative ECOG (Eastern Cooperative Oncology Group) performance status grades were 3.2 and 2.4, respectively. At follow-up, 58.3% of patients had improved status, 31.5% had no improvement, and 10.0% had worsening of functional status. The mean QALY gained per year in the entire cohort was 0.55. The mean QALY gained in the first 6 months was 0.1 and in the first year was 0.4. For patients who lived 1–2, 2–3, 3–4, or 4–5 years, the mean QALY gained were 0.8, 1.4, 1.7, and 2.3, respectively. Preoperative motor weakness, bowel dysfunction, bladder dysfunction, and ASA (American Society of Anesthesiologists) class were identified as independent predictors inversely associated with good outcome.
The mean QALY gained from surgical decompression in the first 6 months and first year equals 1.2 months and 5 months of life in perfect health, respectively. These findings suggest that surgery might also be beneficial to patients with life expectancy < 6 months.