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A Behavioral Phenotype
Lesch-Nyhan behavior is an example of a behavioral phenotype. A phenotype is the external expression of a set of genes. Lesch-Nyhan Disease (LND) is arguably the best example of a behavioral phenotype because of the unique symmetry of gene and behavior: Only those individuals with the missing enzyme display the behavior and only those with the behavior have the missing enzyme. Information about either the gene or the behavior can be used to diagnose the disease. In LND, the behavior is such a good indicator of the gene that behavioral observation can be just as reliable as a biochemical test in diagnosing the disease. A well trained observer and a well conducted lab test will come to the same conclusion. (This is, of course, an academic argument and the formal and final diagnoses must include an analysis of enzyme function.)
This unique convergence of behavior and genetic disease makes LND an important "experiment of nature". Understanding how the behavior results from the enzyme deficiency will be an important advance in understanding brain-behavior relationships. But for now, even though a great deal is known about the genetics, physiology and chemistry of LND, it remains a mystery as to why the genetic flaw results in a behavior change.
Variants of LND. Not every one with LND has the pure form of the disease. If the position on the gene where the lesion occurs does not exactly correspond to the "classic" location, the behavior and biochemistry of the patient will vary from the classic pattern. Some patients have a "variant" of LND where the behavioral and physical characteristics are less predictable. These patients tend to have better motor control and are less likely to engage in LND behaviors. In the "classic" case the activity of the missing enzyme is close to (or is) zero. In general, the more enzyme activity, the more the variation in behavior and physical symptoms. There is thus a "gray area" in diagnosing LND. At some point the variation become too great and the diagnosis of LND is no longer appropriate.
Lesch-Nyhan Behavior
The hallmark of LND is a compulsive drive to self-injure. Patients as young as two years of age will bite their fingers and lips, they will bang their heads and arms, and toss themselves about in attempts to injure themselves. While finger and lip biting are common avenues of self-injury, the number of ways self-injury can occur is limited only by the creativity of the patient and the available of opportunities.
The LND behavioral phenotype is not limited to self-injury. It can be externally directed in attempts to harm others and it can be psychologically directed at themselves and at others. Patients act in ways that brings harm to their self-esteem, their relationships with others and in ways that are counter productive to their own best self-interests. For example, it is common for a patient with LND to try and alienate the people they most care for, to deny themselves pleasure perhaps by saying he does not want to go on an outing he is clearly looking forward to, or he may deliberately give the wrong answer on a test for which he has been studying hard
Of course self-injury and anti-social acts are not unique to LND. Self-injury is common among a variety of psychiatric conditions and antisocial behavior is hardly remarkable. But what makes these behaviors special in LND is the overall context in which they occur. From our mutual reference point of normal behavior, Lesch-Nyhan behavior is inexplicable and counterintuitive in that they clearly do not want to harm themselves or others.
The patients experience pain in the same way as anyone else. When they injure themselves, they cry out in pain. They beg to be restrained in such a way that there is no possibility that they can injure themselves. They are only at ease when all possible avenues of self-injury have been removed. He is full of remorse for the interpersonal insult he has caused, he is distraught at not getting to go on the outing and is dejected after doing poorly on the test.
Making the behavior all the more inexplicable is that the patients are often highly social, have a good sense of humor, are keen observers of their surroundings and care deeply for the well being of others.
Thus while self-injury is the hallmark of LND it may not be the best way to categorize the behavior of Lesch-Nyhan patients. It may be more accurate to think of the patients as doing the opposite of what they actually intend. They do not want to bite themselves yet they do, they are appreciative of the help they receive from a caretaker yet they strike out at them, they want to go on the outing yet they succeed in getting left behind, they want to be successful yet they deliberately fail.
Treatment implications
LND patients can not be adequately cared for unless everyone who interacts with the patient understands the nature of the disorder.
On first encounter, parents, caretakers, teachers and health professionals will be unprepared for dealing with it
An understanding of the behavioral characteristics described above lead logically to effective interventions
Stress reduction. Lesch-Nyhan behaviors occur most often while under stress. The behaviors can be thought of as a stress induced reflex. The most likely stress is the opportunity to self-injure. Behavior problems will occur when the patient is not feeling well, when physically uncomfortable, when he is unable to communicate needs and desires, from inappropriate educational demands or during situations that create poor self-esteem and embarrassment. Keeping stress at a minimum keeps Lesch-Nyhan behaviors at a minimum.
Be sympathetic. Sympathy and understanding is the first line of defense. As described above the behavior is a genetic reflex triggered by stress. Therefore, The initial response of the caretaker must be to look for a reason for the stress. The caretaker may need to readjust a sitting position, listen closely to what the patient is trying to say, give Tylenol or Valium, reassess educational demands or devise better and more clever restraints.
Do not blame the patient. To the uninitiated, the behavior seems to be "on purpose". If one responds to a person with LND like you would to a normal unruly child and attempt to "modify" the behavior by using sanctions and contingencies the problem will intensify. Discipline and punishment, Time out and admonishment make the problem worse.
The caretaker. The caretaker needs to be an exceptional person. The caretaker will be subject to endless physical and emotional abuse. Having just spent a great deal of time and energy to solve a problem, the caretaker is greeted with a head butt, spit at or cursed at. Rather than react with anger the caretaker should notice that the patient feels bad about what just happened, that this was really the opposite of what the patient wanted to do, and the caretaker should ignore the behavior and continue the effort to help and understand the patient. The job is also physically demanding. The patients are "dead weight" and when being lifted, thrash about in all directions at once. Several helpers are needed for bathing, toileting, dressing, and seating.
Continuity of care. It is most important to have a continuity of care. The patient's speech is difficult to understand and each patient's personality is unique. It takes time for caretakers to learn to appreciate the unique nature of the disease, it takes time to train the ear to understand the speech and it takes time to learn the particular needs and aspirations of each patient. Suppose, for example, that the school cafeteria is serving rice pudding for dessert. The caretaker asks "would you like some?" The patient answers "No". The caretaker who is familiar with the patient and knows this is a favorite food will disregard the answer and offer a spoonful. The ideal caretaker will correctly guess that this was a "Lesch-Nyhan" answer designed to inflict self-harm by doing the opposite of what was really intended. Helping the patient cope with "Lesch-Nyhan" behaviors reduces stress. If the caretaker is familiar with the patient and the patient is familiar with his caretaker, the patient is less stressed and his behavior is less problematic.
Activities. The patient needs to be kept interested and active in his surroundings. Activities and outings, social interaction, access to TV, movies, radio, music, communication devices, and computers are important ways to keep the patients daily life interesting and enjoyable. To keep these enrichment activities stress free, the caretaker needs to be aware that each activity can be a potential source of self-injury.
Use of restraints. One of the most important management topics is the design and use of restraints. The perfect restraint keeps the patient both free of self-injury and comfortable. Commercially available devices are usually not as successful as home crafted ones. A cleaver handyman is a Lesch-Nyhan's boys best friend. Different restraints are required for different activities, times of day and mood of the patient.
Most patients are able to participate in the use of restraints. They can request a particular device for a particular activity and they can choose to be free of all restraints for periods of time. Patients can often predict when self-injury will or will not be a problem and alert caretakers in time to reattach the restraints.
Teeth extraction. Teeth extraction is a common way to manage self-injurious biting of the fingers, lips and cheeks. The parent survey by Anderson and Ernst (1994) found that 60% of the patients had teeth extracted in order to prevent self-injury. Parents overwhelmingly endorsed teeth extraction as a way of managing self-biting. The only remorse was that they did not do it quickly enough to prevent tissue loss, particularly to the lips. All of the patients expressed relief at having their teeth removed. If the decision to remove teeth is made, it is best to remove all the teeth, not just the ones currently involved in biting. It is our experience that the patients quickly discover ways to bite themselves using the remaining teeth. Biting is less a problem in the older boys and it may be possible to save the secondary molars.
Teeth extraction is a difficult decision. The most difficult factor in making the decision is that not all patients become finger and lip bitters. Some patients with LND have relatively mild forms of self-injury. In still others, self-injury is completely absent. One does not want to remove the teeth unnecessarily. But, given that the patient is showing signs of finger and lip biting, there are several arguments in favor of the decision:
The physical appearance of the child is largely unchanged. Others tend not to notice that the teeth are missing. The sunken-in appearance of the elderly who have lost their teeth is a result of loss of gums, not the loss of teeth. Whatever the physical affect of teeth extraction might be, it needs to be contrasted to the physical appearance of a child who has bitten away portions of his lips.
Problems associated with meal times and chewing food are largely unaffected. Food must be cut into small pieces and soft food must be prepared in any case. Gums become quite hard and capable of managing french fries and Big Macs.
Diction is unaffected. Clarity of speech is terrible at best, and teeth extraction is unlikely to make it any worse.
Removing the worry of self-biting makes everyone more relaxed.
Ignore the behavior. Ignoring the "Lesch-Nyhan" behavior is often a useful strategy. Some self-injury can be safely ignored because it is "low level" causing little or no physical damage. Cursing, spitting, pinching, head butting etc. are other examples of behaviors that are best ignored. When the behavior can not be completely ignored because of the potential harm to the patient or others, react with the minimum which is necessary to provide protection. Block the behavior but do not overreact. Don't lecture, criticize or admonish the patient.
Distinguishing "LND" behavior from "normal" bad behavior. LND patients can misbehave for the same reasons normal children misbehave. Deciding if the misbehavior is "LND" behavior or normal misbehavior is a constant challenge for parents and caretakers. The best defense is to know the patient well. Parents and long time caretakers develop a fairly accurate sense of this. Experienced parents believe that "normal" misbehavior represents a minority of the occurrences of misbehavior. The preponderance of bad behavior is a result of the disease.
Comparing LND treatment strategies with treatment guidelines for other populations who self-injure. Treatment guidelines and policies regarding the use of restrain that have been developed for other diagnostic groups, in general, are not appropriate for people with LND. In LND freedom from restraints should not be a goal in and of itself. The philosophy surrounding the use of restraints in LND is different than that guiding its use in other populations that self-injure. In managing the more common forms of self-injury (i.e. other than LND) the over reliance on restraints can be problematical. Sometimes the use of restraints is done for the convenience of staff and reflects the inability to understand the source of self-injury. In non LND populations the most common explanation of self-injury is that it is a reinforced operant. Understanding how the behavior is shaped by its consequences and adjusting those consequences so that restraints become unnecessary is an important policy that has the full support of thoughtful observers. However, in LND, effective use of restraints is the avenue by which the LND patient can achieve a maximum of freedom and control.
LND behavior treatment does not rely upon reinforcement and extinction procedures. The reason ignoring behavior is a useful strategy in LND is different from the reason it is effective in standard behavior modification programs. In the non LND case of SIB, the behavior is most commonly under the control of its consequences, i.e. attention paid to the behavior is often a potent source of reinforcement. Ignoring the behavior removes the reinforcer and the behavior "extinguishes". It works differently in LND. When the behavior of a Lesch-Nyhan patient is ignored the incident in smoothed over and the stress associated with performing the behavior (which is most likely the opposite of what the patient intended) is reduced making a repetition less likely. Being sympathetic, discovering what the LND patient needs, talking about the source of distress , etc. reduces the likelihood of unwanted behavior, while the same response in non SIB populations may accidentally reinforce the behavior thus making it worse.