Pituitary Gland Disorders

By Dr. Ravindra Patil

What is the pituitary gland and where is it located?

The pituitary gland is a tiny pea-sized organ located at the base of the brain. Barely a cubic centimetre in volume, it produces and stores so many hormones of our body that it is known as the ‘master gland’. These pituitary hormones control the activity of other hormones in the body.

The pituitary gland has 2 parts: the anterior (front) and the posterior (back) parts, each producing a different set of hormones. Each of these hormones acts on different parts of the body and controls their proper functioning. The pituitary hormones are:

• Prolactin
• Growth hormone
• Adrenocorticotrophic hormone [ACTH]
• Thyroid stimulating hormone [TSH]
• Luteinizing hormone
• Follicle stimulating hormone
• Melanocyte stimulating hormone
• Antidiuretic hormone [ADH]
• Oxytocin

Function of pituitary hormones are vital for human survival. The deficiency or overproduction of each and every of the above hormones results in major medical disorders. For example, a shortage of growth hormone during childhood leads to reduced growth. The child does not grow like a normal adult but remains a dwarf. Conversely, excess of growth hormone leads to gigantism, a condition where the person keeps on growing abnormally.

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Hormones and Hormone Diseases

Hormones are the body’s chemical messengers, sending signals into the bloodstream and tissues. Hormones work slowly, over time, and affect many different processes, including growth and development, blood sugar, sexual functions, reproduction, urine output, managing stress and mood. Hormone diseases occur when the level of any hormone is reduced or increased because of any reason. The Pituitary Gland produces many hormones and any pituitary gland problems lead to major illnesses.

What are common pituitary disorders?

Apart from a deficiency or excess production of the above hormones, disorders of pituitary gland are as follows:

• Tumours
• Pituitary damage because of Head injury
• Birth defects
• Inherited genetic defects
• Low blood supply to the pituitary gland
• Previous history of pituitary disorders
• Iron overload
• Medication
• Radiation therapy in the head and neck region

What are the different types of anterior pituitary disorders?

Anterior pituitary disorders occur as a result of overproduction or underproduction of hormones secreted by the anterior lobes.

     Disorders caused by over-production of anterior pituitary hormones

• Acromegaly & gigantism
• Prolactemia
• Cushing’s disease

     

      Disorders caused by under-secretion of anterior pituitary hormones

• Dwarfism
• Central adrenal insufficiency
• Gonadotropin deficiency
• Hypothyroidism

  

What are the different types of posterior pituitary disorders?

Posterior pituitary disorders are caused by either under-production or overproduction of the ADH hormone. ADH helps the kidneys to prevent excess water loss through urine. Imbalance in ADH production can lead to the following disorders:

• Disorders of ADH secretion
• Diabetes insipidus

Pituitary disorders symptoms: Hypopituitarism

Hypopituitarism is a condition that results in a partial or complete loss of the anterior pituitary gland functions. Panhypopituitarism is a condition, characterized by damage to the entire pituitary gland. In such cases, the production of all pituitary hormones stops. 

Causes of hypopituitarism

• Growth of a pituitary tumour
• Head injuries
• Brain surgery
• Medication
• Radiation therapy

Signs and symptoms of hypopituitarism

• Tumours may cause eyesight problems.
• The symptoms of hypopituitarism depend upon which hormones are no longer being produced.
• Symptoms vary depending upon the age of the patients.

Diagnosis

• Blood tests and stimulation or dynamic testing to identify low levels of pituitary hormones
• Brain imaging using an MRI or CT scan to detect tumour or other pituitary gland problems
• Vision tests to determine if the pituitary gland is affecting eyesight

Pituitary gland disorders treatment

• Hormone replacement therapy: Patients need to take life-long medications to control the symptoms. The doctor monitors and adjusts the medication dose periodically based on the patient condition
• Surgery or radiation treatment may be required in some patients suffering from pituitary tumours

What are pituitary tumours?

Pituitary tumours are abnormal growths in the pituitary glands. They may cause overproduction or low levels of pituitary hormones.  Most pituitary tumours are noncancerous growth and remain confined within the pituitary gland. These are known as an adenomas.

When the tumour size is less than one cm, it is called a Microadenoma. Most pituitary adenomas are microadenomas. When the tumour is greater than one cm in size, it is called a Macroadenoma.

Malignant Pituitary tumours (cancers) are rare and mostly affects old aged persons. Pituitary carcinomas can spread to the brain, spinal cord or the bone surrounding the pituitary glands. In some patients, the pituitary adenoma can turn cancerous and spread to other parts of the body.

 

What is the prevalence of pituitary tumours?

A pituitary adenoma is the third largest cause of brain tumours, accounting for 10% of all cases. The global prevalence of pituitary adenomas is approximately 17%. Studies have reported the risk of pituitary tumours to increase with age, with maximum cases being diagnosed between 30 and 60 years.

What causes pituitary tumours? Are there any risk factors?

The cause of pituitary adenoma remains unknown. Genetic alteration is thought to play an important role in adenoma development. Studies have shown that people with certain genetic factors such as multiple endocrine neoplasia, type 1 (MEN 1) are at increased risk of pituitary tumours.

What are the signs and symptoms of pituitary adenomas?

• Tumours can put pressure on the pituitary gland and the nearby structures. This can cause headaches and loss of side-visions
• As the tumour grows in size, it can damage the normal functioning of the gland and interfere with hormone production. Overproduction or hormonal deficiencies can cause specific signs and symptoms or sometimes a combination of them.
• For example, ACTH tumours exhibit signs and symptoms of Cushing’s syndrome.

Are pituitary tumours life-threatening?

If diagnosed early, pituitary tumours can be managed well. However, if left undiagnosed and untreated for a long period, such tumours can become large and affect the functioning of several organs of the body, causing blindness, hypertension, diabetes, osteoporosis, heart disease and death.

Evidence suggests the 5-year survival rate of pituitary gland tumours be about 82%. 

Survival rate also depends upon factors like:

• Type of tumour
• Person’s age
• How far the tumour has spread in the brain or to other parts of the body

Complications of pituitary tumours

• Blindness
• Permanent hormone deficiency
• Pituitary apoplexy is a rare and serious complication

How are pituitary tumours diagnosed?

• Blood and urine tests help to determine whether there is an overproduction of deficiency of hormones
• Biopsy: This involves removing a small number of cells and examining them under a microscope to check for abnormal growth
• Brain imaging: A CT scan or brain MRI scan can help the doctor to determine the size and location of the tumour
• Vision testing to understand if the tumour has caused eyesight problem
• Neurological exam: A set of questions and answers to check a person’s mental status and appropriate brain functioning controlling movement and coordination.

Pituitary gland diseases treatment

Not all pituitary tumours require treatment. Treatment depends upon the following:

• Type and size of the tumour
• If the tumour is making hormones
• If the tumour is obstructing vision or associated with other signs or symptoms
• If the tumour is localized or has spread to other parts of the body
• If the tumour has occurred for the first time or has recurred
• The patient’s overall healt

  The treatment is usually given by a brain surgeon (neurosurgeon), endocrine system specialist (endocrinologist) and a radiation oncologist. Doctors use a combination of surgery, radiation therapy and medications to normalize hormone levels.

Surgery for pituitary

Surgery is needed when the tumour presses on the optic nerve or leads to the overproduction of hormones. The Endoscopic transnasal transsphenoidal approach involves removing the tumour through the nose without making an incision. This is usually done when the tumour is small in size and no other part of the brain is affected by it. The Transcranial approach (craniotomy) is used for removing large tumours by making an incision in the scalp.

Radiation therapy

This technique uses high-energy radiation to destroy tumour cells. It can be used alone or in combination with surgery.

Medicines

They help to limit excess hormone production and shrink certain types of pituitary tumours.

Hormone replacement therapy is done in patients with reduced hormone production after surgery.

Watchful waiting: Many patients do not exhibit any symptoms and function normally without any treatment. In such cases, patients are advised only regular tests to keep a check on the tumour growth.

To summarise, a disease of pituitary gland can be very harmful. It must be diagnosed and treated as soon as possible. Such complex disease treatment is available in Samarth Neuro and Superspeciality Hospital in Miraj, Maharashtra. Dr. Ravindra Patil, the chief neurosurgeon there, is an expert in performing such operations.

Ventricles of the Human Brain

By Dr. Ravindra Patil

A ventricle is a hollow part or cavity in an organ. The word ventricle originates from Latin, the language which has given most of the words used in anatomy and medicine. Ventricles of brain are cavities within the brain. Ventricles of the brain have distinctive functions, which we will see in this article.

Two major organs of the major organs of the human body which have ventricles are the heart and the brain. The ventricles of the heart pump blood through our body, while the ventricles of the brain are cavities within the brain that produce and store a liquid called cerebrospinal fluid (CSF). This liquid surrounds our brain and spinal cord, cushions them and protects them from injury. The CSF is also responsible for removing waste and delivering nutrients to our brain.

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Where in the brain are the ventricles?

There are four ventricles in the brain. They are interconnected cavities. They extend throughout the brain. As has been mentioned, they produce, store and circulate the cerebrospinal fluid (CSF).

The two lateral ventricles of brain are C-shaped chambers found in the cerebral hemispheres, which is one in each hemisphere.

Lateral ventricles are connected to the third ventricle by an opening called the inter-ventricular foramen. The third ventricle is a very narrow cavity that runs along the midline of the diencephalon.

What structure connects the third and fourth ventricles? The third ventricle communicates with the fourth ventricle via the cerebral aqueduct. The fourth ventricle is wedged between the cerebellum on one side and the brainstem on the other; it extends to the central canal of the spinal cord. Which means in effect, the four ventricles extend from the brain to the end of the spinal cord. The CSF surrounds the brain and is also within the ventricles. The CSF is a liquid cushion in which the brain literally floats. The brain ventricles essentially supply, store and circulate the CSF around the brain.

The CSF is a thick viscous fluid which serves to cushion the brain, regulate its temperature and supply the brain with nutrients.

More about the brain ventricles

When looking at the interior of the brain, the four hollow ventricular cavities stand out in contrast to the rest of the organ, which is mostly composed of brain tissue, which in turn is made of grey matter and white matter. The main ventricle function is of course, producing CSF.

As the ventricles contained nothing except fluid, in ancient times it was thought that the ventricles contained ‘animal spirits’, a mysterious substance that allowed the immortal soul to exert control over the physical body. Later it was thought that the ventricles were credited with functions like the generation of imagination and memory. However, it was in 1764 that it was discovered that the ventricles were filled with CSF, fluid, and not animal spirits. And the CSF flowed around and inside the brain through the connections between ventricles. The ventricles gave the CSF a route to flow throughout the brain. Gradually it was discovered that it is the production, storage and circulation of CSF which is the main role of the ventricles.

How is CSF produced?

The production of CSF is done by a specialized membrane called the choroid plexus, which is made up of ependymal cells. This choroid plexus lines the ventricles in brain. Ependymal cells are glial cells tailored to produce CSF, and they secrete the fluid into the ventricles at a relatively constant rate; about a half a litre of CSF is produced by ependymal cells every day. CSF passes through the ventricular system and circulates around the brain and spinal cord in a small area between the meninges called the subarachnoid space.

Functions of the CSF

CSF is thought to play many important roles in the brain. The CSF and the brain ventricular system together keep the brain buoyant, reducing its weight and hence the physical stress it would otherwise experience from the forces of gravity and movement. The brain is a very delicate and soft organ. If the  brain would not have been suspended in the CSF, it would have been distorted with its own weight! While organs like the kidney and liver and heart are much sturdier, the brain is very soft. Without being suspended in a fluid the delicate tissue of the brain can tear.

There is about 125–150 mL of CSF at any one time. The actual mass of the human brain is about 1400–1500 grams; however, the net weight of the brain suspended in CSF is equivalent to a mass of 25-50 grams. The brain therefore exists in neutral buoyancy, which allows the brain to maintain its density without being impaired by its own weight. Had the brain been suspended in the skull without floating in the CSF, its blood supply would have been cut off and its neurons would be killed in the lower sections of the brain!

The layer of CSF surrounding the brain also acts as a buffer against potential injuries that can be caused by mechanical pressure or force (e.g. being hit hard in the head). Additionally, as the CSF circulates over the brain it carries away toxins and other waste matter and empties these into the bloodstream where they can eventually be removed by mechanisms like kidney filtration.

Ventricles and the CSF

The rate of CSF production in the ventricles is fairly constant regardless of changes in pressure within the ventricles (i.e. inter-ventricular pressure). This can be problematic if the passage of CSF is blocked somewhere within the ventricular system. In the ventricular system of brain, CSF will continue to be produced, but it will have no means of exiting the system. This will cause pressure within the ventricles to increase, and the rising pressure may eventually force the ventricles to expand. The expanding ventricles can then put pressure upon other brain structures, and cause a variety of complications depending on where exactly the blockage has occurred and which structures are most affected by the blockage.

When such a blockage of the brain ventricles occurs in children whose skull has not completely become bony [generally under age of 2 years], it results in the enlargement of the head. It is known as hydrocephalus. Hydrocephalus can be cause by blockage in the passage of CSF as well as by excess CSF production. In lay language, hydrocephalus is referred as ‘Water in the Brain’.

There can be a number of causes of a blockage that leads to hydrocephalus, such as a tumour, infection, or congenital malformation, which impedes the function of ventricles. Hydrocephalus can often be treated by surgically implanting a shunt that drains the ventricles of excess CSF and empties it into the abdominal cavity. This approach can be successful, but if the reason for the blockage isn’t resolved additional surgeries may be required in the future (e.g. to replace an outgrown shunt, treat an infected shunt, etc…).

How is blockage in ventricles diagnosed?

A contrast CT Scan can show the size and shape of the ventricles in brain. Either a radiopaque dye is injected in the patient’s veins or the CSF is replaced with air and then CT Scan of brain ventricles is done. In either case, a good contrast will be seen and the ventricles can be visualised. While the radio opaque dyes shows up as white colour, air shows up as black colour in CT scans and that helps doctors view the ventricular shape and size and reach a diagnosis about tumours, raised CSF pressure or blockage in the brain ventricular system.

Samarth Neuro and Superspeciality Hospital in Miraj has all the infrastructure and staff to treat hydrocephalus in children and other reasons of CSF blockage. The chief neurosurgeon Dr Ravindra Patil has operated upon many children suffering from hydrocephalus who needed shunts. These children are now grown up. Dr Ravindra Patil has also successfully operated on many adult patients with brain tumours.