The senses are used to gather information about the environment and the internal body, and most people are aware of the five main senses: visual (sight), olfactory (smell), gustatory (taste), auditory (hearing), and tactile (touch). There are also three more senses that are not generally known: vestibular, proprioception, and interoception. All eight of these senses are very important, and disruption can cause many issues for the person involved. When all of the senses are working together at an optimal level, an individual has a reliable picture of the environment and their internal status. Patients for whom any one of these systems is not processing stimuli accurately have a different experience than those around them.

The gustatory sense provides information about the taste of foods and liquids. A disrupted gustatory system may cause severe feeding issues. Many patients with sensory processing dysfunction are "picky" eaters for a number of reasons, one of which might be a gustatory system disruption. When gustatory issues are worked on, feeding issues often improve.

Hyperacusis occurs when a patient's auditory system is too sensitive, causing pain when a louder noise is noted (e.g., a fire truck goes by on the street). In the clinic, louder medical instruments may bother a person with a sensitive auditory system. It can be helpful to discuss the device before it is used and/or to provide a quieter area or noise-canceling headphones to address these issues during health care.

The second subsystem is the discriminatory system, which helps people determine the quality of the object they are touching. This system helps categorize things as hard or soft or smooth or rough. Dysfunction in this area can cause difficulties with such daily fine motor activities as buttoning a coat and handwriting. These persons might avoid certain textures of food, clothing, and surfaces [10]. Poor tactile discrimination is often a focus for sensory therapy.

The vestibular system senses the position of the head in space (i.e., spatial orientation), including direction and speed of head movement. This system involves the structures of the inner ear in conjunction with vision and the auditory system. Difficulty in the vestibular system results in low muscle tone, poor balance, poor coordination, and improper reactions to movements [3,10]. There is an anatomical association between the vestibular and auditory systems, and it is often found that a specific type of vestibular stimulation combined with auditory input results in an improved ability to communicate [9].

Neural systems around the internal organs form the interoceptive system. These nerves detect and transmit information about internal regulation responses, such as thirst, waste elimination, and fullness. In a very young child, difficulty with interoception can lead to delayed toilet training success. Issues with interoception may result in a person reporting headache, stomachache, or other pain in confusion with other sensations, which could result in confused diagnosis [9].

SMD is characterized by a difficulty regulating sensory stimuli. Patients may be over-responsive, meaning they have the tendency to respond too much, too soon, or for too long to sensory stimuli most people find tolerable [14]. They often have a "fight-or-flight" response to sensation (e.g., being touched unexpectedly), which is sometimes called "sensory defensiveness" [14]. These patients are bothered by usually tolerable stimuli (e.g., the seams in a shirt).

Individuals with SBMD can regulate sensory input but have difficulty with balance, motor coordination, and the performance of skilled, not-habitual, and/or habitual motor tasks. SBMD is sometimes co-exhibited with SMD [16]. There are two subtypes of SBMD: postural disorder and dyspraxia [14,16].

Distraction is also an important tool. If a young patient will receive a reward at the end of the visit, he or she can be asked to pick it out first. Deep pressure often calms a patient with sensory issues, and a patient in the dental office might prefer to keep the weighted X-ray shield apron on during the visit to help calm the sensory system. Of course, it is important to consult with the patient and/or parent to determine if this would help [29].

There are also a few key things that clinicians should avoid when dealing with patients with sensory processing issues. If the patient is a child, it is important not to exclude the parent. The parent can serve as a translator and filter for the child, and in some cases, patient report can come from the parent. Some medical offices prefer to take patients back without the parent, but this is not helpful for patients with sensory processing challenges unless the visit is for occupational or physical therapy. Instead, parents should be considered part of the healthcare team. Older patients should be acknowledged as being their own expert, with the knowledge of necessary steps to take to be more comfortable.

Sudden movements should also be avoided whenever possible. Patients with sensory processing dysfunction function better with an announced or visual schedule from which they can work. Discussing procedures beforehand and allowing patients to see and, if safe, handle equipment can be beneficial. Keeping patients advised on the next two or three steps that will occur in the visit will help decrease anxiety. Letting them know when the visit will be over is also good practice.

Some clinicians will downplay patients' fears and dismiss them as unnecessary, but this can add to anxiety. It is best to listen to the patient and validate his or her fears and pain while also explaining the purpose of the procedure at the appropriate cognitive level. Talk through motor activities using directional and spatial terms [10].