Dr. Cheung’s Blog 11/9/2013

Dr. Cheung’s Blog 11/9/2013

November 9, 2013

Only time will tell

The twins continue to thrive since my last blog entry.  They stayed at the Swedish neonatal intensive care unit for a little over two weeks , mostly for feeding and growing.  Except for their small sizes, they appeared otherwise healthy to us and to their doctors.  They have roughly tripled in size in three months – they literally jumped on the growth curves.  Elise was less than one percentile at birth and is now running at 14%.  Theo is a tank in comparison, approaching 69% tile.  Babies like my twins who were premature and growth restricted in utero are at risks of a host of medical problems including cerebral palsy, attention deficit disorder, autism, asthma, reflux … all sound very scary as a father.  While the logical and medical side of my brain tells me that there is no evidence of any of these conditions, there is still an underlying tinge of fear.  Only time will tell.

That’s the thing about physicians prognosticating.  It is an educated guess based on statistics but there is no way we can tell whether YOUR child, YOUR spouse, or MY child will be free of a particular aliment.  In pediatrics, we develop milestones to help us gauge the development of a baby, make better predictions and to intervene when necessary if the baby falls significantly off the trajectory.

For example, misalignment of the eyes is very common in early infancy.  Approximately, 75% of neonates have wandering eyes, 25% have straight eyes and a very small percentage have crossed eyes.  Look at Elise and Theo in these pictures.

Their left eyes appear crossed but their daddy is not freaking out – yet.  This is still within the norm, particularly if it is intermittent.  By three months of age (corrected for prematurity), most normal infants will have straight eyes.  If their eyes remain crossed by then, I would be calling my associate, Dr. Barrall. For now, patience is the best course of action.  In fact, the congenital esotropia observational study confirmed in 2002 that small degree of crossed eye (less than 40 prism diopter) identified at less than 20 weeks of age frequently resolves without any treatment.

Parents often wanted to know how much their baby is seeing.  Is it 20/40?  What is normal?  That is actually not a good milestone to gauge visual development in an infant.  It is neither accurate nor practical.  How much a baby “sees” depends on how we measure it.When measured using sophisticated electrodes attached to the scalp (Visual Evoked Potential) while the baby observes a reversing pattern on a monitor, the acuity of a full term newborn is estimated to be 20/100 to 20/200.    The acuity typically increases rapidly between one to three months and approaches 20/80 by 4 months.  VEP tends to overestimate acuity in infants and some babies can measure close to 20/20 by 6 months with this method.  However, this is a very time consuming way to measure acuity and it is subject to many variables such as the alertness and attention span of the baby.  In clinical practice, this is rarely done unless other alarming signs such as nystagmus (jiggling eye movements), extreme light sensitivity and poor visual attention are also present.

Another common myth is that newborns can only focus up to about 10 inches from their faces.  Most infants are born far-sighted (hyperopic), which means that it is easier for them to see things far away than at up close.  Optically speaking, in a relaxed, unaccomodated hyperopic eye, there is no clear focal point from infinity to the cornea.  Accommodation –the contraction of the focusing muscles in the eye, is generally believed to be poor or absent until three to four months of age. Therefore, the neonates will have a defocused image at all distances but they tend to look at things at about 10 inches because that is where their objects of interest are located – the parent’s faces or the approaching mothers breasts or bottles.

The physical characteristics of the structure of the eyes are good milestones and reference points for eye doctors.  At birth, the average corneal diameter of a full term infant is 9.8 mm just 2.0 mm shy of the adult value of 11.7mm.  A large cornea and loss of clarity of the cornea will raise concerns for congenital glaucoma, a rare but potentially devastating eye disease.  The front to back diameter of the newborn eye (axial length) is about 16mm, compared to the adult value of 23mm.  The most rapid growth phase occurs in the first 18 months of life when the white wall of the eye (the sclera) drastically expands.  The color part of the eye, the iris, becomes darker after birth as pigments accumulate in the cells and the meshwork of this lacy structure.  In Caucasians, the eye color is typically set by six months of age.

What about at the other spectrum of life?  We don’t typically look at developmental milestones in seniors as they are done growing.  However, we can look for markers to monitor degeneration and predict the time course of a disease.  Ultimately, however, only time will tell.

In the eye, for example, genetic testing is now commercially available for age related macular degeneration (AMD).  Using the DNA from a mouth swab, the Retna Gene test can evaluate the risk of a patient with the dry form of the disease progressing to the advanced, wet form of the disease.  While it does not change what we can do for those patients identified as high risks, the test can educate and impart on the patients the importance of periodic follow up.  This test is now available at our offices for those patients who fit the criteria.

The most dreaded neuro-degenerative disease in the senior population is, of course, Alzheimer’s.  My mother was diagnosed with early-onset Alzheimer’s five years ago.  She now lives in Hong Kong and it has been difficult to watch her slowly decline from a distance.  I am not sure if she would understand who the twins are when she finally meets them.  I also know that it will be a matter of time when she would no longer recognize my voice when I call.  A glimmer of hope now exists for early detection and possibly treatment for Alzheimer’s.  The hallmark of Alzheimer’s disease is the deposition of an amyloid protein in the brain causing the neurons to tangle.   This same amyloid protein also accumulates in the retina and if we can measure the level of amyloid in the eye, we might be able to correlate with the disease in the brain.  Researchers recently identify a compound, Curcumin, a derivative of turmeric or curry, which binds to the amyloid protein.  This Curcumin molecule also naturally fluoresces and by measuring the amount of fluorescent light coming from the retina using a specialized camera, scientists can deduce the amount of amyloid protein in the eye and by extension, in the brain, after the patient ingests a dose of Curcumin.  Since there is still no effective cure for Alzheimer’s disease at this time, it is our hope that early detection can allow for a more effective treatment before the neurons turn into plaques and tangles with the amyloid protein deposition.

As physicians, we are often frustrated by the limited effective options we can offer our patients with chronic diseases such as Alzheimer’s or Cerebral palsy.  We tried our best to educate and reassure our patients, but we all know that the outcome is unknown and only time will tell.  Reflecting on my experience as a father and as a son, I think that a little bit of hand-holding from a caring physician can go a long way even in the face of a terminal condition.  I like to think of chronic disease as a long journey and as your doctor, my role in these situations is to travel the distance with you, offer guidance when appropriate and take a little burden off you when needed.  While only time can tell the ultimate destination of this journey, it goes a heck a lot faster when we walk hand-in-hand.