The somatosensory cortex processes sensory input from the body. It lies next to the primary motor cortex, which helps control movement. When the somatosensory cortex sustains damage, it can result in sensory deficits and, due to its location, even affect movement and balance.

In this article, you will learn more about somatosensory cortex damage, what effects it can cause, and how these effects are rehabilitated.

What Is the Somatosensory Cortex?

The somatosensory cortex is responsible for processing all bodily sensations. These sensations come from receptors found throughout the body that detect temperature, pain, touch, weight, and proprioception (your awareness of the location, movement, and action of your body).

Each section of the somatosensory cortex is arranged so that a particular area receives sensory information from a certain part of the body. Areas of the body that are more sensitive, such as the hands and lips, take up more space in the cortex than others.

This is illustrated in the cortical sensory homunculus, which represents the proportions of the brain dedicated to sensory function for different body parts:

As you can see, large amounts of the cortex are dedicate to the face and hands, which means that these areas are more vulnerable to impairment after somatosensory cortex damage.

The somatosensory cortex lies within the parietal lobe on a ridge of the cerebral cortex called the postcentral gyrus. This region of the brain contributes to proprioception. Therefore, an individual with somatosensory cortex damage may not only develop sensory issues but may also develop motor issues linked to poor proprioception, such as loss of balance and coordination.

Secondary Effects of Somatosensory Damage

Damage to the sensory cortex can cause a variety of effects, depending on where the damage occurred. Every brain injury is different, and every person’s brain is wired a bit differently. Therefore, every person with somatosensory cortex damage will experience the effects differently too. Some survivors may sustain a number of effects while others may only sustain one or two.

Common secondary effects of somatosensory cortex damage include:

Numbness or Paraesthesia

Somatosensory cortex damage can result in numbness or tingling/prickling sensations (paraesthesia) in certain parts of the body depending on where the damage occurred. Since the face and hands have the most receptors and take up the largest area of the cortex, they are vulnerable to numbness and/or tingling.

Each hemisphere of the brain generally controls movement and sensation on the opposite side of the body. Therefore, when sensory issues occur after somatosensory cortex damage, it usually occurs on the opposite side of the body to the damage.

Injury to the sensory cortex can also cause problems with the ability to detect heat or cold. This poses a safety risk because the survivor may not be able to recognize when a surface may be dangerously hot, such as an electric stove burner.

Defective Localization

Lesions on the sensory cortex can cause problems with identifying where on the body a sensation occurs. The person might be able to recognize that a feeling is coming from their hand or arm. But they would not be able to point to a specific place on their hand. In severe cases, the survivor may not even be able to locate where the sensation is coming from at all.

Loss of Proprioception

Proprioception refers to the ability to recognize where the body is in space. It’s what allows people to walk without constantly watching their feet, for example. Proprioception also makes you aware that your arms are moving when you walk.

This sense is controlled by receptors located in the muscles, joints, and tendons. These receptors detect various input like movement speed and stretched muscles and send this information to the brain.

After damage to the somatosensory cortex, however, this skill can become diminished. As a result, actions such as balancing, walking, and even reaching can be more difficult.

People with proprioceptive problems are also more vulnerable to muscle sprains or tears because they cannot sense when their muscles are being over-stretched.

Agraphesthesia and Tactile Agnosia

Similarly, somatosensory cortex damage can cause difficulties with recognizing things traced on the skin. For example, a person with this problem would not be able to tell whether an X or an O was written on the palm of their hand.

People with this disorder often also have trouble identifying an object by touch alone. If their eyes are closed, they cannot tell if they are holding a fork, a pen, or a book. It all feels the same. This is known as tactile agnosia.

Treating Somatosensory Cortex Damage

Many of the effects of somatosensory cortex damage involve sensory changes or motor difficulties. Fortunately, the brain is capable of healing and rewiring itself through neuroplasticity. As survivors work towards recovery, the brain can make adaptive changes and potentially improve its ability to process sensory input and/or effectively move the affected muscles.

Here’s an overview of the two major types of therapy that can help survivors after somatosensory cortex damage:

Sensory Reeducation

Sensory reeducation, also known as sensory retraining, is a form of therapy that helps retrain the brain to process sensation again. It works by exposing the individual to repetitive sensory stimuli to spark neuroplasticity and encourage adaptive changes in the brain.

For example, if you struggle with numbness after somatosensory cortex damage, you can try doing a temperature differentiation exercise. With the help of a caregiver or therapist, soak one washcloth in cold water and one in hot (but not too hot) water. Then, alternate placing the cloths on the affected areas and try to determine the temperature.

Even if you cannot feel anything yet, sensory reeducation exercises like these help stimulate the brain and encourage adaptive changes. It can take many weeks or months of consistent practice to feel results. Try to practice for about 15 minutes a day to encourage improvements in sensory effects such as numbness or paraesthesia. Your occupational therapist is an excellent resource for sensory stimulation activities, too.

Proprioceptive Training

When survivors experience a loss of proprioception after somatosensory cortex damage, it can create difficulty with activities that involve balance such as walking. It can also increase the risk of falling. Therefore it’s essential to work with a physical and/or occupational therapist to address this problem.

Your therapist will take you through a series of proprioceptive training exercises that will target your proprioceptive skills. For example, your therapist may ask you to stand on one foot while holding onto something for safety. This exercise will likely be challenging if you have a loss of proprioception, and it will send positive stimulation to the brain.

Your therapist can also help you incorporate other beneficial therapies to improve proprioception such as passive or active exercise, electrical stimulation, and vibration therapy. These extra therapies provide more stimulation to the brain, and a combination of techniques appears to be most effective.

Overcoming Somatosensory Cortex Damage

After somatosensory cortex damage, some survivors experience sensory- or movement-related effects like numbness, tingling, or poor balance. Fortunately, through rehabilitative therapies like sensory retraining and proprioceptive training, it is possible to recover at least some of your sensory and/or motor function.

Improvements in the effects of somatosensory cortex damage are thanks to neuroplasticity: the brain’s ability to heal and rewire itself after injury. Your therapist is an excellent resource for exercises that help target your unique effects and stimulate positive changes in the brain.

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