Introduction

Definition of gerstmann syndrome

There was a scientist called Joseph Gerstmann who discovered a syndrome and named it after himself, and now it's called Gerstmann syndrome.¹

This syndrome is characterised by four main signs: if a person has all four of them, it is called a pure Gerstmann syndrome.

Overview of clinical features (finger agnosia, left-right disorientation, agraphia, acalculia)

These four signs are:

1. Finger agnosia: being unable to recognise, name or distinguish one's own fingers 
2. Acalculia: being unable to perform arithmetic operations  and use numbers
3. Agraphia: being unable to write properly 
4. Right-left disorientation: being unable to differentiate right from left¹

This syndrome is usually accompanied by lesions in a certain area of the brain.

It is also very rare, and that causes controversy around it, as usually these four signs are not all found in the same patients and sometimes associated with other disorders.¹

Anatomical basis

Localisation of lesions

Hemispheric specificity (left hemisphere dominance)

The lesions associated with Gerstmann syndrome are located in the left hemisphere of the brain( the left half of the brain). Some studies have proved that the lesions associated with this syndrome are located exactly in the left posterior part of the parietal lobe.¹

Parietal lobe involvement

The parietal lobe of the brain is responsible for our understanding of what is surrounding us and is responsible for the sense of touch and all the inputs from other senses

This explains why a patient with this syndrome has some difficulties in distinguishing their own fingers and from left to right.

In some other cases of this syndrome, the lesions were found elsewhere in the brain, such as in the middle of the frontal lobe.¹

Pathophysiological mechanisms

Studies proved that there are some diseases that can lead to having Gerstmann syndrome like cerebrovascular diseases( diseases that affect the blood flow reaching the brain), traumatic brain injuries ( injuries to the brain that result from being hit on the head or being exposed to a violent blow), neurodivergent diseases( diseases that result from abnormalities in the brain) and degenerative diseases like ALzheimer's.² 

Vascular etiology

Stroke and ischemia

Some vascular issues can affect the brain, leading to the signs and symptoms of Gerstmann syndrome, such as suffering from ischemia or a stroke.²

Ischemia is a condition that happens to a part of the body, in this case, we are talking about the brain, due to decreased blood flow to this part, causing the tissue to die.

Ischemia in the brain can lead to some changes in the brain functions and can be one of the reasons leading to Gerstmann syndrome.²

A cerebrovascular accident or a cerebrovascular stroke ( it occurs when there is no blood flow reaching the brain, depriving it of oxygen and nutrients), if not treated, can lead to loss of some functions of the brain, depending on which part of the brain was cut off from blood supply and also can lead to a person suffering from Gerstmann syndrome.²

Being a hypertension patient can increase the risk of suffering from some neurological complications, including Gerstmann syndrome.²

Traumatic brain injury

Mechanisms of injury leading to parietal lobe damage

Some injuries the brain is subjected to can lead to damage in the parietal lobe. This damage is in the form of disconnection in the networks made of some nerves in the brain.

Cortical damages in the parietal lobe occur as well in degenerative diseases like Alzheimer's, dementia and Progressive supranuclear palsy ( a rare disease that affects balance, swallowing and eye movement). This explains why degenerative diseases can cause Gerstmann syndrome.⁴

Other neurological disorders

Inability to perform certain functions that the parietal lobe is responsible for is not only due to damage in the parietal lobe.

These functions are carried on through nodes made of nerves connecting either a cortical part of the brain with another cortical part or a cortical part with a subcortical part, so any disturbance in these networks or nodes will lead to dysfunction.⁴

Epilepsy and seizures

Both epilepsy and seizures are neurological disorders affecting these networks in the brain, which lead to Gerstmann syndrome.

Tumours and mass effects

One of the things responsible for this dysfunction is the presence of a lesion causing breakage or disconnection in these networks, leading to Gerstmann syndrome.⁴

Some other neurological disorders (diseases affecting the nervous system) can cause these disconnections, leading to signs and symptoms related to Gerstmann syndrome.

Developmental and pediatric considerations

Can children and adolescents have gerstmann syndrome?

Case reports in children

Studies have shown cases where a child can have significant reading skills but still suffer from right-left disorientation, Acalculia( being unable to perform arithmetic operations and use numbers), and Agraphia(being unable to write properly)

These signs and symptoms in children and adolescents were considered developmental.³

Researchers found that almost all children who had developmental Gerstmann syndrome also had dyslexia (inability to read properly) and dysgraphia (inability to write correctly).³

Differential diagnosis

Conditions with overlapping symptoms

Gerstmann syndrome is called pure when the four signs and symptoms are all found in the patient without any other symptoms. These four symptoms are Finger agnosia, Acalculia, Agraphia and Right-left disorientation.

If there is a patient who doesn't have the full tetrad or has them and other symptoms as well, in that case, it is not diagnosed as Gerstmann syndrome and is diagnosed as something else according to the symptoms this patient has.

These other symptoms may include dyslexia, apraxia (inability to say certain words or make certain movements) and dyspraxia( a disorder that causes difficulties in some movements).

This makes pure Gerstmann syndrome very rare to find, as there will always be an overlap with other diseases or one or two symptoms only are found and can be treated.

Prognosis 

The prognosis of patients with Gerstmann syndrome is favourable, although the lesions are usually located on the left side of the brain, which is the dominant side, and it can be treated.

Symptoms like Agraphia and Acalculia can be treated with different kinds and types of therapies, such as speech therapies and occupational therapies ( therapies that help perform everyday activities in the correct way).

Summary 

Gerstmann syndrome is a syndrome affecting the parietal lobe in the brain, specifically the left parietal lobe. Patients having Gerstmann syndrome often suffer from Finger agnosia, Acalculia, Agraphia and Right-left disorientation. 

They also suffer from lesions in the brain, causing damage and disconnection, leading to an inability to do certain things and perform certain functions.

Gerstmann syndrome is caused by different reasons like ischemia, stroke and cerebrovascular diseases. Some degenerative diseases like Alzahimar’s can lead to this syndrome, and some neurological disorders like seizures and epilepsy are also considered causes. 

Some children can have what is called developmental Gerstmann syndrome, which is a condition characterised by Acalculia, Agraphia, and Right-left disorientation in addition to dyslexia.

When a patient only has the four symptoms of Gerstmann syndrome and nothing else, it is called a pure Gerstmann syndrome. But that is not what usually happens because usually the signs and symptoms of Gerstmann syndrome overlap with other symptoms like dyslexia and apraxia.

The prognosis of this syndrome is favourable, and its symptoms can be treated by different kinds of therapy.

FAQs

What is the cause of gerstmann's syndrome?

Gerstmann syndrome can be caused by cerebrovascular accidents, Ischemia, epilepsy, neurological disorders and degenerative disorders.

What artery is affected by gerstmann syndrome?

The middle cerebral artery is affected in the case of Gerstmann syndrome.

Is gerstmann's syndrome left or right?

The left side of the brain is affected by Gerstmann syndrome.

What is gerstmann syndrome of the inferior parietal lobule?

Usually, the posterior or inferior part of the left parietal lobe of the brain is the part affected in Gerstmann syndrome.

What causes finger agnosia?

Finger agnosia is related to brain damage, especially in the posterior part of the parietal lobe in the dominant half of the brain, which is usually the left half.

What are the neurological disorders of the parietal lobe?

Finger agnosia: being unable to recognise, name or distinguish one's own fingers 

Acalculia: being unable to perform arithmetic operations  and use numbers

Agraphia: being unable to write properly 

Right-left disorientation: being unable to differentiate right from left