Saturday, November 9, 2013
Corpus callosotomy, Alien hand syndrome...
Corpus callosotomy is a palliative surgical procedure for the treatment of seizures. As the corpus callosum is critical to the interhemispheric spread of epileptic activity, the procedure seeks to eliminate this pathway. “Efficacy and relatively low permanent morbidity in corpus callosotomy for medically intractable epilepsy have been demonstrated by more than six decades of experience. In addition to seizure reduction, behavior and quality of life may improve.”
The corpus callosum is usually severed in order to stop epileptic seizures. Once the corpus callosum is cut, the brain has much more difficulty sending messages between the hemispheres. Although the corpus callosum is the largest white matter tract connecting the hemispheres, some limited interhemispheric communication is still possible via the anterior commissure and posterior commissure. When tested in particular situations, it is obvious that information transfer between the hemispheres is reduced.
The most prominent non-surgical complications of corpus callosotomy relate to speech irregularities. For some patients, sectioning may be followed by a brief spell of mutism. A long-term side effect that some patients may suffer is an inability to engage in spontaneous speech. In addition, the resultant split-brain prevented some patients from following verbal commands that required use of their non-dominant hand.
Another common complication is alien hand syndrome, in which the afflicted person's hand appears to take on a mind of its own.
"Alien hand syndrome"
The patient complained of a feeling of "strangeness" in relationship to the goal-directed movements of the left hand and insisted that "someone else" was moving the left hand, and that she was not moving it herself. Goldstein reported that, as a result of this report, "she was regarded at first as a paranoiac." When the left hand grasped an object, she could not voluntarily release it. The somatic sensibility of the left side was reported to be impaired, especially with aspects of sensation having to do with the orienting of the limb. Some spontaneous movements were noted to occur involving the left hand, such as wiping the face or rubbing the eyes; but these were relatively infrequent. Only with significant effort was she able to perform simple movements with the left arm in response to spoken command, but these movements were performed slowly and often incompletely even if these same movements had been involuntarily performed with relative ease before while in the abnormal 'alien' control mode.
Damage to the corpus callosum can give rise to "purposeful" actions in the sufferer's non-dominant hand (an individual who is left-hemisphere-dominant will experience the left hand becoming alien, and the right hand will turn alien in the person with right-hemisphere dominance).
In “the callosal variant”, the patient’s hand counteracts voluntary actions performed by the other, “good” hand. Two phenomena that are often found in patients with callosal alien hand are agonistic dyspraxia and diagonistic dyspraxia.
Agonistic dyspraxia involves compulsive automatic execution of motor commands by one hand when the patient is asked to perform movements with the other hand. For example, when a patient with callosal damage was instructed to pull a chair forward, the affected hand would decisively and impulsively push the chair backwards. Agonistic dyspraxia can thus be viewed as an involuntary competitive interaction between the two hands directed toward completion of a desired act in which the affected hand competes with the unaffected hand to complete a purposive act originally intended to be performed by the unaffected hand.
Diagonistic dyspraxia, on the other hand, involves a conflict between the desired act in which the unaffected hand has been engaged and the interfering action of the affected hand which works to oppose the purpose of the desired act intended to be performed by the unaffected hand. For instance, when Akelaitis’s patients underwent surgery to the corpus callosum to reduce epileptic seizures, one patient’s left alien hand would frequently interfere with the right hand. For instance, while trying to turn over to the next page with the right hand, his left hand would try to close the book.
In another case of callosal alien hand, the patient did not suffer from intermanual conflict between the hands but rather from a symptom characterized by involuntary mirror movements of the affected hand.
When the patient was asked to perform movements with one hand, the other hand would involuntarily perform a mirror image movement which continued even when the involuntary movement was brought to the attention of the patient, and the patient was asked to restrain the mirrored movement. The patient suffered from a ruptured aneurysm near the anterior cerebral artery, which resulted in the right hand being mirrored by the left hand. The patient described the left hand as frequently interfering and taking over anything the patient tried to do with the right hand. For instance, when trying to grasp a glass of water with the right hand with a right side approach, the left hand would involuntary reach out and grasp hold of the glass through a left side approach.
More recently, Geschwind et al. described the case of a woman who suffered severe coronary heart disease. One week after undergoing coronary artery bypass grafting, she noticed that her left hand started to ‘‘live a life of its own’’. It would unbutton her gown, try to choke her while asleep and would automatically fight with the right hand to answer the phone. She had to physically restrain the affected hand with the righ hand to prevent injury, a behavior which has been termed "self-restriction." The left hand also showed signs of severe ideomotor apraxia. It was able to mimic actions but only with the help of mirror movements executed by the right hand (enabling synkinesis). Using magnetic resonance imaging (MRI), Geschwind et al. found damage to the posterior half of the callosal body, sparing the anterior half and the splenium extending slightly into the white matter underlying the right cingulate cortex.
***I remember learning about this in Psychology when I was in college,
in the 1990's, only to actually work with someone that had that done
when I worked at a Marriott hotel as a banquet server.
He had some conflict. He told me his "Right brain is jealous of the left
because the right hand does all the work."
There was onetime he hit himself with the left hand.
I had to know what eye - side of the brain to look at to tell
him to knock it off. He thanked me for that!
But overall he was a happy guy! He had his bad times, but
found happiness by carrying two trays of food one in each hand.
"Im happy!" he said. The boss didn't like that but I pulled out
my old college books and showed her, hes not normal and needs
not to be chained to a standard due to his needs!
The Brain is amazing!