Answer: Gerstmann's syndrome is a specific cognitive impairment resulting in difficulty with writing, math, and spatial skills.
Gerstmann's syndrome is a constellation of symptoms that result in various intellectual challenges.
Typically, Gerstmann’s syndrome is only diagnosed if all four of the following deficits are observed:
Finger Agnosia. A patient may have a difficult time identifying and distinguishing differences between their fingers. To perform this test, the patient will close their eyes and extend their fingers towards the experimenter. The experimenter will gently tap one of their fingers. A healthy patient is expected to be able to identify the finger touched by name (thumb, index, middle, ring, or pinky). A patient who demonstrates finger agnosia will not be able to accurately name the touched finger.
Dyscalculia, or a more severe symptom called acalculia. Patients with these symptoms have a difficult time understanding or applying the rules of mathematics. For example, they may also have difficulty with performing mental math tasks (addition, subtraction, multiplication, and division) without writing the numbers down, even if they take their time. Relatedly, they may not be able to successfully rearrange the numbers 5, 8, and 2 in ascending order.
Dysgraphia or agraphia. These patients have difficulty using writing as a means of communicating ideas. There is not a definitive test for dysgraphia, which makes it challenging to diagnose and identify. However, some clues that dysgraphia is present include difficulty with producing illegible handwritten text, challenges with spelling or other grammatical elements, or highly irregular spacing between letters.
Left-right disorientation. This symptom is observed when the patient is unable to clearly and accurately use or interpret the words left and right. For example, they may be asked to touch their right leg with their left hand. While they could repeat these instructions accurately, they may not be able to perform the action properly - they might touch their right leg with their right hand, for example.
It is important to note that the list of four symptoms above are required for a diagnosis of Gerstmann's Syndrome. The syndrome can appear even in people with a standard range of IQ.
In younger patients, it may present as a developmental disability.
In addition to these cognitive behavioral tests, a suspected case of Gerstmann's syndrome may also be followed up by some type of brain imaging method, such as a CAT scan or an MRI. These tools can help identify if an injury in the angular gyrus is present and if urgent medical interventions are necessary.
Causes of Gerstmann’s Syndrome
In adults, the most common cause of Gerstmann’s syndrome is an injury to the brain. Specifically, injury to the left angular gyrus, the region of cortex near where the parietal, temporal, and occipital lobes meet. Sometimes, it appears after injury to the right angular gyrus as well.
The nature of the brain damage may vary. Sometimes, a cardiovascular event such as an aneurysm, or ischemic or hemorrhagic stroke of the middle cerebral artery might damage the cells of the angular gyrus. These causes may require surgical intervention.
Other cases of Gerstmann's syndrome may result from toxin exposure or a tumor.
Sometimes, symptoms appear temporarily during parietal lobe epileptic seizure.
Repairing the damaged tissue or treating the cause (removal of toxin exposure, tumor) may be able to reverse the cognitive deficits.
Prognosis
Adults diagnosed with Gerstmann’s Syndrome following a stroke may eventually recover their full capabilities. Over time with support, the patient's brain may be able to compensate for the damaged areas, possibly through plasticity mechanisms as rewiring can take place.
In children, it is unclear what causes it. Many children learn subtle workarounds to avoid using the cognitive functions that are impaired.