Short-Term Memory Following Brain Tumor Surgery

Brain tumor surgery and other kinds of traumas to the brain can affect short-term memory. Short-term memory is the capacity for temporarily storing chunks of information of varying complexity. Because information held in short-term memory forms the input to long-term memory, short-term memory loss affects the ability to learn and to remember recent events.

Brain Tumors

• A brain tumor is an abnormal growth of cells in the brain or its protective membranes. Benign, or non-aggressive, tumors are slow-growing and do not penetrate surrounding tissue or spread to other parts of the body. Malignant, or aggressive, tumors are fast-growing and can infiltrate surrounding tissue. Whether brain tumors are benign or malignant, they can cause damage to surrounding brain tissue as they grow. Most brain tumors are surgically removed, and any remaining abnormal growth is treated with radiation.

Complications

• Because it is difficult to remove a tumor without destroying neurons, one of the most common complications of brain tumor surgery is short-term memory loss. Short-term memory loss involves debilitating changes in the brain's neural connections. A neural connection is a group of neurons that tend to "fire" together. This tendency to fire in familiar patterns is also known as "potentiation." When the brain suffers a trauma to an area that stores information, the neurons in that area are no longer able to engage in short- or long-term potentiation.

Rehabilitation

• Rehabilitation after brain tumor surgery that results in memory loss typically involves psychotherapy and cognitive therapy. Psychotherapy can help patients cope psychologically with the changes in their condition. Cognitive therapy is an intervention that can help patients learn and retain information. A so-called spaced-retrieval method also can be used to enhance the storage of sensory information. The method involves asking a patient to identify a designated object from an array of items at increasingly longer intervals.

Stem Cell Therapy

• While there is currently no guaranteed way of reversing short-term memory loss after brain tumor surgery and other traumas to the brain, stem cell therapy offers a possible solution. Frank M. LaFerla, a professor of neuroscience, and his colleagues at the University of California-Irvine found that when mice with induced memory loss were injected with stem cells, they developed synapses, or connections between neurons, at the damaged site. After the treatment, injured mice performed as well on memory tests as the healthy control mice.

Deep-Brain Stimulation

• Deep-brain stimulation is another promising way to tackle memory loss after brain tumor surgery. In deep-brain stimulation, electrodes are implanted into the patient's brain, and electric current stimulates the damaged areas. Neurosurgery expert Andres Lozano and his colleagues discovered the positive effects of deep-brain stimulation when they attempted to control the appetite of a patient who suffered from obesity. The patient suddenly had vivid memories of an event that had occurred 30 years earlier. The technique has since been used to reverse memory loss in Parkinson's and Alzheimer's patients, but the hope is that it will have therapeutic benefits for patients with other types of memory problems.