Appropriate concentration of acetic acid for the preservation of fresh cadaveric brains to be used in surgical training: a preliminary study / Concentración adecuada de ácido acético para la preservación de cerebros de cadáveres frescos para uso en entrenamiento quirúrgico: un estudio preliminar

A small amount of acetic acid (AA), a common preservative, has been shown to increase contamination in cadaveric tissue, while larger concentrations can lead to the tissue becoming hard, especially in fresh brains. This study attempted to optimize the concentration of AA to be used in the cranial cavity in order to produce the most realistic consistency and color. Six adult cadaveric heads were preserved with descending glacial AA at concentrations of 98.5 %, 80 %, 60 %, 40 %, 20 %, and 10 %. The samples were kept at 5 °C for 14 days. The brain cortex was then dissected with a suction tube and forceps to reveal the underlying brain tissue for inspection. Color change, cortical firmness, pia mater stickiness, and participant satisfaction were evaluated. The color of the brains in all concentrations was slightly yellow. However, the temporal area of the brain preserved using 20 % AA was significantly more pink. The pia mater of the brain cortex of all samples was firm and difficult to pry apart, with the firmest consistency being in the brain tissue preserved using 98.5 % AA. The brain tissue in all samples had a liquid-like consistency. The brains preserved in AA at a concentration greater than 60 % yielded higher satisfaction scores. We conclude that acetic acid has a role in brain preservation for skull base surgery training and recommend AA concentrations higher than 60 % for maximal participants satisfaction.

Se ha demostrado que una pequeña cantidad de ácido acético (AA), un preservante común, aumenta la contaminación en el tejido del cadáver, mientras que mayores concentraciones pueden endurecer el tejido, particularmente en cerebros frescos. Este estudio intentó optimizar la concentración de AA en la cavidad craneal para producir una consistencia y coloración cerebral más cercanos a la realidad. Seis cabezas cadavéricas adultas se conservaron con AA glacial descendente en concentraciones de 98,5 %, 80 %, 60 %, 40 %, 20 % y 10 %. Las muestras se mantuvieron a 5 °C durante 14 días. Luego se diseccó la corteza cerebral con un tubo de succión y pinzas para observar e inspeccionar el tejido cerebral subyacente. Se evaluaron el color, la firmeza cortical, la viscosidad y adherencia de la piamadre y la reacción de los participantes ante esta conservación. El color de los cerebros en todas las concentraciones fue ligeramente amarillo. Sin embargo, el área temporal del cerebro, conservada con un 20 % de AA, fue significativamente más rosada. La piamadre de la corteza de todas las muestras fue de consistencia firme y difícil de separar; una mayor resistencia se observó en el tejido cerebral preservado con 98,5 % de AA. La consistencia del tejido cerebral en todas las muestras era líquida. Los cerebros conservados en AA a una concentración superior al 60 % recibieron puntuaciones de satisfacción más elevadas. Concluimos que el ácido acético desempeña un papel en la preservación del cerebro, permitiendo el entrenamiento en cirugía de base de cráneo, por lo que recomendamos concentraciones de AA superiores al 60 % para una satisfacción máxima por parte de los participantes.

Efficacy and factors determining the outcome of dorsal root entry zone lesioning procedure (DREZotomy) in the treatment of intractable pain syndrome.

BACKGROUND: Chronic pain is a disabling condition that adversely affects patient quality of life. The dorsal root entry zone lesioning procedure (DREZotomy) is a modality used to treat intractable pain caused by insults to neural structures. This study aimed to investigate the efficacy of and the factors that determine the outcome of microsurgical DREZotomy (MDT). METHOD: All consecutive patients who underwent MDT for treatment of intractable pain during September 2008 to December 2016 were enrolled. Demographic data, clinical characteristics, intraoperative findings, and postoperative outcomes were analyzed. RESULTS: The 40 included patients underwent MDT for relief of intractable pain caused by 27 brachial plexus injuries (BPIs), 6 spinal cord injuries, 3 neoplasms, and 4 other causes. A significant reduction in pain was observed post-MDT for both average (p < 0.001) and maximal pain (p < 0.001). Favorable outcome (≥50% pain reduction) was observed in 67.5% of patients, with the best outcome in BPI-related pain. In multivariate analysis, injury of the spinal nerve root (root avulsion or injury) was significantly associated with good average pain relief (OR, 5.8; 95% CI, 1.2-27.5; p = 0.026) and pain freedom (OR, 5.0; 95% CI, 1.12-22.30; p = 0.035). Electrical pain (OR, 6.49; 95% CI, 1.20-35.19; p = 0.030) and lower number of painful dermatomes (OR, 1.30; 95% CI, 1.01-1.67; p = 0.039) were significantly associated with good maximal pain relief. CONCLUSIONS: MDT is an effective procedure for treatment of intractable pain in well-selected patients, particularly in cases with brachial plexus avulsion pain. Injury of the spinal nerve root (brachial plexus avulsion and cauda equina injury) was associated with good average pain relief and pain freedom, and electrical pain and lower number of painful dermatomes were associated with good maximal pain relief. The results are useful in the selection of candidates for DREZotomy and prediction of surgical outcome.