What is Prosencephalon Disease in Cats?

prosencephalon
prosencephalon

The prosencephalon in cats is another term for the forebrain which is the anterior part of the brain. To help you better understand the prosencephalon, we will review some basic information about the cat brain.

The physical structure of the cat brain is very similar to our brains. The brain is part of the neurological system and located within the skull. It is a soft mass of pinkish gray nerve tissue. The other major portion of the nervous system is the spinal cord which attaches to the base of the brain. Together the brain and spinal cord make up the central nervous system. Nerves found throughout the rest of the body make up the peripheral nervous system.

The brain is divided into three compartments: the brain stem, cerebrum and cerebellum.

  • Brainstem – is the area at the base of the brain that controls basic life functions. The brainstem is connected to the cerebellum and the spinal cord.
  • Cerebrum – is the area that forms the bulk of the brain that controls conscious decision-making. It is divided into two parts – the right and left cerebral hemispheres.
  • Cerebellum – is the back part of the brain that controls movement and posture.

The brain, spinal cord, and nerves transmit signals throughout the body that allow cats (and us) to learn, think, walk, run, and even breathe. Nerve impulses transmit signals to our organs that control function. The brain also controls sensory impulses such as taste, smell, hearing, vision and pain.

What Does the Cat Prosencephalon Do?

The prosencephalon, also known as the forebrain, is the part of the brain in the front of the skull that consists of the cerebrum, thalamus and the hypothalamus. A normally functioning prosencephalon allows your cat to behave normally, recognize you, walk, react, and respond to stimuli in the environment.

Signs of Prosencephalon Disease or Abnormalities in Cats

Symptoms of prosencephalon disease in cats may include any or all of the following depending on the exact part of the brain affected.

  • Head pressing can be an important symptom of prosencephalon disease of cats. Learn more about other possible causes of Head Pressing in Cats.
  • Abnormal behavior or mentation including:
  • Demented (abnormal behavior such as perceived memory impairment, changes in vocalization, changes in behavior, inappropriate behavior)
  • Obtunded mentation – which is a decreased sensitivity or dullness
  • Coma – non-responsive to normal stimuli
  • Stupor – decreased responsiveness to normal environmental stimuli
  • Gait – cats with abnormalities of the prosencephalon generally have a normal gait unless there is concurrent disease with other parts of the brain. Some cats will have diminished postural reactions.
  • Reflexes – reflexes can be normal or increased
  • Eye or vision changes
  • Blindness – cats with prosencephalon disease may be blind due to impact to cranial nerve II that is responsible for vision. This can occur in one or both eyes.
  • Abnormal pupil sizes – cats with forebrain disease may have decreased pupillary light reflexes which can causes either large pupils or a difference in pupil sizes from one eye to the other depending on the part of the prosencephalon involved.
  • Circling or head tilt
  • Circling or head turns can occur with prosencephalon disease. Generally the cat may circle or turn toward the side of the brain lesion.

Diagnostic Tests to Determine Prosencephalon Disease in Cats

Basic diagnostic tests to evaluate abnormalities of the prosencephalon may include:

  • A complete physical exam including a thorough neurological examination. This exam includes testing of reflexes, will provide valuable information on the function of the brain and spinal cord.
  • Basic blood work and urinalysis are recommended to evaluate for systemic disease. The complete blood count (CBC) may be within normal limits, but an elevated white blood cell count may be present if there is also secondary infection. A biochemical profile and urinalysis may be unremarkable depending on concurrent medical problems.
  • Radiographs of the chest and abdomen are an important part of any baseline work-up. Abdominal radiographs (X-rays) may be within normal limits or can reveal signs of cancer or concurrent disease.
  • Abdominal ultrasound is recommended to evaluate for signs of cancer or concurrent disease. This is a noninvasive procedure that often necessitates the expertise of a specialist in a referral hospital.
  • Skull radiographs may provide information about the bony skull around the brain, and the vertebrae that surround the spinal cord. This is most commonly recommended when there has been a history of trauma.

Advanced diagnostic tests are important methods to evaluate abnormalities of the prosencephalon. The most important are computed tomography (CT) and magnetic resonance imaging (MRI). Tests may include:

  • Computed tomography (CT scan or CAT scan) is a special X-ray technique that provides serial images of the brain using enhanced computer processing. CT is a good way to assess fractures of the skull or tumors involving the bone.
  • Magnetic resonance imaging (MRI) is a diagnostic test in which powerful magnetic fields generate detailed images of body organs. MRI is a very useful tool in evaluating the soft tissue of the brain.
  • Brain stem auditory evoked response (BAER) is an electrodiagnostic test to detect hearing abnormalities (deafness).
  • Electroencephalogram (EEG) is an electrodiagnostic test used to detect peripheral nerve function and abnormalities in brain activity such as with seizure disorders.
  • Cerebrospinal Fluid (CSF) Tap in Cats is a test that involves collecting cerebrospinal fluid that is found in the space surrounding the brain and spinal cord. The analysis often provides valuable information as to the presence of infection, inflammation, and other abnormalities.

Possible Diseases of the Prosencephalon in Cats

There are various diseases that affect the forebrain of cats. They include:

  • Arachnoid cysts – can form and squeeze the prosencephalon in cats. They can be removed surgically.
  • Bartonella henselae – is a bacteria responsible for cat-scratch fever that can also infect humans. Infection can cause meningoencephalitis in cats. Antibiotics are the treatment of choice.
  • Choroid Plexus Tumors – are uncommon tumors but can occur in cats. They can be difficult to remove surgically and can metastasize.
  • Coccidioides immitis – is a fungal infection most common in the Southwest United States. It is found in the soil and can infect the lungs, bone, eye, skin and nervous systems of cats. Antifungal drugs are the mainstay of treatment.
  • Cryptococcus neoformans – is a fungal infection that can infect the central nervous system of cats. Cats are exposed to the organism from access to the bark or soil that can spread to the lungs and brain.
  • Antifungal drugs are the mainstay of treatment.
  • Cuterebra – can lay eggs near the burrows of animals, attach to the skin, and the larvae migrate into the skin. These larvae can eventually migrate to the brains of cats. There are various treatment options that include steroids therapy, antibiotics, antihistamines and ivermectin therapy.
  • Feline Immunodeficiency Virus (FIV) – is a disease caused by a retrovirus and most commonly spread from bite wounds in outdoor male cats. FIV can cause inflammation in the brain. No effective treatment has been defined.
  • Feline Infectious Peritonitis Virus (FIP) – is a disease resulting from coronavirus that can occur most commonly in young cats but can also occur in older cats. Inflammation develops in the brain that can cause mild to severe clinical signs. In addition to neurological signs, there are often additional signs of illness that may include fever, weight loss, and/or decreased appetite. No successful treatment has been documented when FIP spreads to the brain.
  • Feline Leukemia Virus (FeLV) – is a disease resulting from a retrovirus that can directly affect the nervous system of cats. Treatment involves minimizing the chance of secondary infections and immunomodulation therapy.
  • Glioma – is another type of brain tumor that can affect the prosencephalon of cats. They are often aggressive tumors and can be challenging to treat with surgery, radiotherapy, or chemotherapy.
  • Granulomatous Meningoencephalomyelitis (GME) – is an inflammatory disease that occurs in the brain tissue. The underlying cause is unclear, theories that may include immune-medicated, viral, and cancer as possibilities. Treatment often focuses on steroids for immunosuppression and immunomodulator drug therapy.
  • Hydrocephalus – is an abnormal accumulation of CSF within the cranium. It can occur from obstruction of CSF or from loss of brain tissue. It is most common in toy-breed dogs and is considered rare in cats.
  • Lymphoma – is a type of cancer that can develop in the brain or metastasize to the brain from another location. Some tumors respond to radiotherapy or chemotherapy but the prognosis is generally considered to be poor.
  • Meningioma – is brain tumor that can affects senior pets. Treatment may include surgery depending on the location of the tumor. Radiation therapy or medical therapy such as with steroids can help decrease swelling around the tumor.
  • Metastatic tumors – are tumors that develop in some primary location in the body and metastasize to the brain. Sources may include hemangiosarcoma, lymphoma, prostatic cancer, and melanoma.
  • Pituitary tumors – such as or macroadenomas can occur but are more common in older dogs than cats. These are generally slow growing tumors that can respond well to radiotherapy.
  • Toxoplasma gondii – can infect the lung, nervous system, liver and muscle of cats. Antibiotics are the treatment of choice.

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