Snowdrop

What is Absence of the Septum Pellucidum?

Absence of the septum pellucidum (ASP) is a rare disorder, (occuring in an estimated 2 to 3 individuals per 1 00,000 people in the general population). It is characterised by abnormal development of a thin membrane located at the midline of the brain. It runs down from the corpus callosum, the structure which connects the two cerebral hemispheres of the brain and effectively acts as a separator for the two hemispheres. The disorder usually occurs with other neurological abnormalities such as agenesis / dysgenesis of the corpus callosum.

Individuals with ASP may experience vision impairment or blindness. They may also have coordination problems and hormone deficiencies that result in short stature. Intelligence is usually affected and learning disabilities are common. The disorder usually manifests early in life, often as a consequence of discovering the other neurological abnormalities, such as corpus callosum abnormalities or septo – optic dysplasia. Symptoms include involuntary eye movements, a wasting of a part or parts of the body, and short stature. Seizures and inappropriate behaviour, such as displays of 'sham rage' may also occur. The cause of ASP is currently unknown.

What is the prognosis?

The prognosis of ASP varies depending on the severity of co-occurring abnormalities. Many cranial abnormalities are life threatening, but alone ASP is not a life-threatening disorder.

Can ASP be treated?

When a part of the brain is actually missing, - having not developed at all, then obviously no amount of treatment is going to be able to restore that missing neurology. What we can strive to do is to enable the neurology which is present to function at maximum efficiency and therefore give the child the opportunity to achieve his / her maximum potential. We believe that that at Snowdrop, we teach parents how to provide an appropriately stimulating developmental environment for this to happen

The Pons is located in the lower brainstem, directly above the Medulla Oblongata. The word 'pons' means 'bridge' and this is an apt description as it acts as a bridge which connects the cerebellum to higher brain structures. It's involvement with the cerebellum makes it an important player in the coordination of movement and posture.

The Pons is also involved in sensory analysis... for example, information from the ear first enters the brain in the pons at the level of the Eighth cranial nerve. It is therefore easy to imagine how many of the distortions of sensory processing experienced by our children can be produced by injury here!  It has parts that are important for regulating our level of consciousness and for sleep, which fits in nicely with the fact that the raphe nuclei are serotonin producing neurons. Injury to the Pons can cause coma. The pons contains the raphe nuclei which contain serotonin, a type neurotransmitter which is instrumental in mediating mood and sleep. The pons is also involved in our ability to perceive pain. Regulation of specific direction of gaze is also controlled at the pons and so a good indicator of injury to this structure is the absence of a pupillary light reflex.

Another important set of nuclei in the pons is the Locus Coereleus. This area of the brain is intimately involved in REM (dream) sleep. It is these nuclei which are responsible for many stress reactions, including 'post traumatic stress disorder.' The locus ceruleus is activated by stress, and will respond by producing a neurotransmitter called 'norepinephrine,' - a form of adrenaline. Injury here is why some of our children are hyper-anxious and oversensitive in sensory terms. Norepinephrine also increases cognitive function and motivation.

So injury to the Pons is capable of producing coma, causing sleep disturbances, sensory disturbances, lack of pupillary response, dysfunction in levels of arousal and attention and increases in levels of stress and anxiety. How many of our children who suffer conditions such as cerebral palsy and autism have injuries to this structure? I would suggest it is more than one would imagine.

Can an injury to the Pons be treated?

Yes! We know that the brain has a high degree of plasticity, - the ability to reorganise it's structure and functioning according to the demands of the environment in which the individual finds himself. We also know that if we can gain an improvement in functioning in one part of the brain, then we can expect 'knock - on' effects, - improvements in other parts of the brain due to the rich connectivity between all areas of the brain. What we do at Snowdrop is to provide children (and adults) with an envionment which is designed to stimulate their development by encouraging this plasticity and improved functioning.

The Medulla Oblongata lies right at the bottom of the brainstem. It's functions are to control respiration, heart rate, swallowing, vomiting, blood pressure and coughing. It also acts as a relay station for nerve fibres, which are descending from the cortex, which cross over at the level of the medulla. This ensures that the right cortical hemisphere controls the left hand limbs of the body and vice versa.

Because of the functions which are the responsibility of the medulla, injury to this part of the brain often proves fatal. Because several cranial nerves carrying sensory information from the environment enter the brain at the level of the medulla, injury can cause many sensory complications. For instance, injury here can cause numbness and paralysis of the palate and throat, difficulty swallowing, leading to excessive drooling and disturbances of taste. It can also cause 'acid reflux,' gagging and inability to rotate the head. There are obvious implications amongst these problems for the development of language and communication.

Despite the high fatality rates for injuries to this part of the brain, I do occasionally see children who are displaying obvious signs of the involvement of the medulla in their injuries. They include children with both cerebral palsy and autism.

Can an Injury to the Medulla be successfully treated?

The brain is highly plastic and any part of our neurological structure is capable of making new connections if we can create the right environment for it to do so. What is the 'right environment?' Well that depends upon to particular pattern of injury experienced by the individual, but an environment which comprises the appropriate level of stimulation can improve the functioning of all areas of the brain. This is what a Snowdrop programme is tailored to acheive.