Introduction

What is Gerstmann syndrome?

Gerstmann syndrome is a rare neurological condition comprising four distinct symptoms.

First, acalculia refers to the patient's struggle with performing calculations, whether orally or in writing. This can significantly impact a person's everyday activities, particularly in managing finances. Next, finger agnosia occurs when an individual has trouble accurately recognising their fingers. Third, agraphia refers to difficulties with writing. Lastly, left-right disorientation occurs when a patient has difficulty distinguishing between the left and right sides.

Certain cases might show signs of aphasia, which is characterised by challenges in verbal expression or comprehension of spoken language, as well as difficulties with reading or spelling. Developmental Gerstmann syndrome can be seen in both damaged and undamaged brains in children, with symptoms typically emerging once they begin their education. These children often struggle with handwriting and math abilities. They may find it hard to comprehend or read words and to replicate simple shapes or objects. The condition affects both boys and girls equally.^1,2

Causes

Gerstmann’s syndrome is caused by brain lesions in the posterior parietal lobe, typically in the left hemisphere, affecting areas like the angular gyrus. The parietal lobe has a role in sensation, perception and understanding sensory input. It may also involve the left middle frontal lobe. Lesions in this region are not the only cause, as involvement of this section in the dominant hemisphere of the brain may also lead to this syndrome. Some of these causes include:¹

• Stroke (impaired blood flow)
• Traumatic brain injury
• Brain tumour
• Chronic subdural haematoma
• Multiple sclerosis
• Cortical atrophy
• Alcoholism
• Lead poisoning
• Carbon monoxide exposure

Differential diagnosis

Gerstmann syndrome can be confused with disorders exhibiting similar symptoms. Examples of some of these disorders include:

• Alzheimer’s disease
• Posterior cortical atrophy (PCA)

Diagnosis

Physical examination and medical history

The patient goes through a thorough physical examination, and a comprehensive medical history, especially regarding any strokes or brain injuries, should be collected to assess the symptoms and how they have progressed. This information is vital for the physician to establish an accurate diagnosis and identify the underlying cause.¹

Neuropsychological tests

Neurological tests are necessary to identify the four aspects of Gerstmann's syndrome.^1,2,3

Finger agnosia

Several tests are conducted to confirm that the individual might have finger agnosia. 

• Patients are asked to close their eyes and reach their fingers out towards the examiner. Then, the examiner taps one of the fingers. A healthy individual will be able to identify the finger by name (index, middle, ring, pinky, or thumb), while a person with finger agnosia will not be able to name the finger that was touched. To eliminate issues with alertness or comprehension, the test is first conducted with the patient's eyes open. For a diagnosis of finger agnosia, the patient must demonstrate at least 20% incorrect recognition
• A two-finger test consists of the examiner making contact with the patient's fingers at two different spots, either on the same finger or on different fingers
• In the homologous finger test, the examiner touches one finger on the patient's hand, and the patient is required to move the matching finger on the opposite hand
• The finger strip test requires the patient to organise five strips of paper, each labelled with the name of one of the five fingers, in the correct order as they are positioned on the hand

Acalculia

A patient should receive a card featuring the straightforward equation "85-27" and be instructed to write it down and solve it. Afterwards, the patient should be asked to perform a multiplication problem mentally, without writing it down or looking at it.

Agraphia

A doctor should present a clock to the patient, who will then write down its name without initially verbalising it. Next, the doctor should display the word “SEVEN” to the patient, who, after reading it and stating it aloud, will be asked to write it down. Following this, the patient should repeat the phrase “He shouted the warning” and then provide an explanation and write it out.³

Left-right orientation

The physician should provide the patient with a card that contains instructions like “bring your left hand to your right ear.” The patient should be encouraged to read it out loud. If the patient misreads the instruction, the physician should engage with the patient verbally, after which the patient should be asked to follow a similar directive.³

Brain scan

A computed tomography (CT) scan or magnetic resonance imaging (MRI) can determine whether a brain lesion situated in the angular gyrus of the left parietal lobe affects adjacent regions. The irregularities detected in the scans will vary depending on the cause of the syndrome. 

Identifying Gerstmann syndrome in children at an early stage can be difficult because of the gradual development of the parietal lobe's functions. Further evaluations might be performed to rule out other disorders, such as dementia in adults or overall learning disabilities in children.¹

Complications

As the symptoms of Gerstmann's syndrome become more pronounced, the related lesions typically grow in size, resulting in more significant neurological deficits. Patients exhibiting all four components of this syndrome are more likely to experience significant brain function decline, and the lesions often threaten the patient's survival and quality of life.¹

Treatment and management

There is no cure for Gerstmann syndrome. The treatment centres around managing symptoms using rehabilitation therapies to improve the quality of life. The effectiveness of the therapies varies from one person to another, depending on the type and severity of the underlying conditions.

Some causes of Gerstmann's syndrome may be reversible and can be treated, including the removal of a tumour, managing haemorrhages, or reducing lesions caused by epilepsy. Additionally, treating underlying causes like carbon monoxide exposure can also be beneficial.¹

Occupational therapy

Occupational therapy helps with daily tasks, such as eating, dressing or writing. Occupational therapists concentrate on enhancing fine motor skills and assist in modifying the environment to support the execution of everyday activities.³

Technological support

The challenges associated with communication and writing can be overcome by providing technological assistance, such as word processors or calculators that help them perform activities independently.³

Prognosis

Underlying conditions accompanying Gerstmann syndrome can interfere with daily activities due to significant right-left disorientation. When developmental Gerstmann syndrome is diagnosed early and paired with intensive speech therapy, children may experience improvements.¹

Summary

Gerstmann syndrome is a rare neurological condition characterised by four main symptoms: acalculia (difficulty with calculations), finger agnosia (trouble recognising fingers), agraphia (difficulties in writing), and left-right disorientation (difficulty distinguishing left from right). Some cases may also show signs of aphasia, which involves challenges in speaking and understanding language. In children, symptoms often appear as they start education, affecting their handwriting, math skills, and overall comprehension. The syndrome affects both AMAB and AFAB equally.

The syndrome is caused by lesions in the posterior parietal lobe of the brain, mainly in the left hemisphere. Conditions leading to these lesions include stroke, traumatic brain injury, brain tumours, chronic subdural hematoma, multiple sclerosis, alcoholism, and exposure to toxins. Gerstmann syndrome can sometimes be confused with other disorders like Alzheimer’s disease. Diagnosis involves a thorough physical examination and history taking, along with neuropsychological tests to assess the specific symptoms. Tests for finger agnosia require patients to identify their fingers or engage in other finger-related tasks. Acalculia is assessed through simple arithmetic problems, while agraphia is examined by having the patient write certain words. Left-right orientation is tested with verbal instructions. Imaging scans like CT or MRI can help identify brain lesions related to the condition. There is no cure for Gerstmann syndrome.

Treatment focuses on managing symptoms through rehabilitation therapies and support. Occupational therapy aims to assist patients with daily tasks and improve fine motor skills. Technology, such as word processors and calculators, can help individuals overcome communication and other challenges. The prognosis for those with developmental Gerstmann syndrome can improve with early diagnosis and speech therapy. However, significant complications can arise from the condition, potentially impacting brain function and overall quality of life.