About subacute cerebellar degeneration

What is subacute cerebellar degeneration?

Subacute cerebellar degeneration (SCD) is characterized by the deterioration of the area of the brain concerned with muscle coordination and balance (the cerebellum). Less frequently, the area involved may include the area connecting the spinal cord to the brain (the medulla oblongata, the cerebral cortex, and the brain stem). There are two types of subacute cerebellar degeneration: paraneoplastic cerebellar degeneration, which sometimes precedes the diagnosis of cancer, and alcoholic or nutritional cerebellar degeneration, caused by a lack of the vitamin B-1 (thiamine). These two types share symptoms but not the same cause.

What are the symptoms for subacute cerebellar degeneration?

Common symptoms of SCD include:

1) Weakened muscle coordination (ataxia) of the limbs (especially of the arms in paraneoplastic cerebellar degeneration, and of the legs in alcoholic or nutritional cerebellar degeneration); (2) Problems in articulation of speech (dysarthria), which are especially noticeable in paraneoplastic cerebellar degeneration;  (3) Difficulty in swallowing (dysphagia); (4) Loss of reason (dementia); this occurs in approximately half the patients with paraneoplastic cerebellar degeneration; (5) Involuntary rapid movements of the eyeball in a horizontal or vertical direction (nystagmus); as well as double-vision (diplopia), vertigo (dizziness), and Paralysis of the eye muscles (ophthalmoplegia) if the patient has alcoholic/nutritional cerebellar degeneration; (6) Cell loss localized to the midline structures of the cerebellum contributes to poor motor coordination of the head, such as head bobbing and loss of limb movements (7) Tremors (shaking) related to complex motor tasks or purposeful movements due to abnormal Purkinje cells (a particular kind of nerve cell) throughout the cerebellum; (8) Repetitive behaviors in children (hand clapping, rhythmic rocking, twirling of objects) associated with cerebellar vermis damage; (9) Problems with cognitive and emotional regulation (autism, schizophrenia, attention deficit-hyperactivity disorder)

In addition, patients with SCD lose many Purkinje cells throughout the cerebellum. Computerized axial tomography (CAT) scans may show enlargement of the area of the brain between the spinal cord and the rest of the brain (fourth ventricle) as well as areas of the cerebellum. Examination of cerebrospinal fluid may show a high volume of lymph cells (white blood cells formed in lymphoid tissue) and an elevated protein level.

What are the causes for subacute cerebellar degeneration?

Paraneoplastic cerebellar degeneration may potentially be an autoimmune disorder. Autoimmune disorders are caused when the body’s natural defenses against invading organisms mistakenly attack healthy tissue for unknown reasons. It may also be an abnormal response to cancer. In cases where there is an underlying cancer, the individual’s immune system may react to the cancer by stimulating the body’s natural defense mechanisms. These natural defense mechanisms include producing antibodies, which are proteins that help the immune system detect harmful substances, and increase the number of T-cells, which are white blood cells that destroy infected cells and tumors. These antibodies and T-cells normally target only the cancerous tumors; however, in paraneoplastic cerebellar degeneration, these antibodies bind to and attack normal cells in the nervous systems, such as Purkinje cells in the cerebellum, leading to their death and loss of function. Purkinje cells are cells specifically found in the cerebellum that gather multiple signals throughout the brain to control motor movements.   Some antibodies and cancers appear to have a direct role in causing paraneoplastic cerebellar degeneration. Hodgkin’s disease, small-cell lung cancer (SCLC), breast, and gynecologic cancers are strongly linked to paraneoplastic cerebellar degeneration. In the absence of a detected tumor, some of these antibodies may still be produced in individuals with paraneoplastic cerebellar degeneration. These antibodies react with Purkinje cells, causing inflammation in the brain and cell death.   Alcoholic/nutritional cerebellar degeneration is associated with thiamine deficiency. The human body needs thiamine, also known as vitamin B1, to function properly. Humans need to consume thiamine in their diet because they are unable to produce it within the body. Once consumed, thiamine becomes absorbed in the small intestine and is stored in the liver. Thiamine is an essential vitamin for the brain and other tissues and is important for many cellular processes. This includes glucose metabolism and energy production, which are required for normal brain function. A reduction in thiamine will impair cellular energy production and, therefore, disrupt brain function. In addition, heavy alcohol use and thiamine deficiency will cause inflammation in the brain, leading to brain damage. Secondary thiamine deficiency results from impaired absorption or utilization or from increased requirements for thiamine. Individuals with a history of chronic alcohol abuse tend to eat poorly and may not get enough thiamine-containing foods. They also absorb or utilize the vitamin less efficiently, due to the effect of alcohol on the liver, and therefore, may require larger than normal amounts of thiamine.

What are the treatments for subacute cerebellar degeneration?

Standard therapeutic options for paraneoplastic cerebellar degeneration include diagnosing and treating the underlying cancer. Prompt tumor removal, chemotherapy and/or radiation may be beneficial and help reduce symptoms in patients. Adjuvant therapy with glucocorticoids such as methylprednisolone and immunotherapy with potent T cell inhibition, such as rituximab and tacrolimus may be elusive. However, small cases have shown both rituximab and tacrolimus may help to stabilize symptom progression in patients with paraneoplastic cerebellar degeneration only. For alcoholic/nutritional cerebellar degeneration, thiamine is given along with other B vitamins, usually relieving the condition if the patient stops drinking alcohol and resumes a normal diet. Physical therapy with focus areas on strengthening, balance and gait balance can help to restore function and prevent long term disability in patients with progressive symptoms. Occupational therapy may focus mainly on activities of daily living and dysphagia rehabilitation.

What are the risk factors for subacute cerebellar degeneration?

In paraneoplastic cerebellar degeneration, the average age of onset is 50 years, with females affected more often than males. This form of cerebellar degeneration may precede cancer, however <1% of patients with cancer have paraneoplastic cerebellar degeneration. Alcoholic or nutritional cerebellar degeneration affects alcoholics and people with thiamine deficiency. In alcoholic cerebellar degeneration, symptoms usually occur in middle aged individuals who have a history of chronic alcohol abuse. 

Is there a cure/medications for subacute cerebellar degeneration?

Subacute cerebellar degeneration (SCD) is characterized by the degradation of the brain region responsible for muscular coordination and balance (the cerebellum). Less frequently, the region linking the spinal cord to the brain may be implicated (the medulla oblongata, the cerebral cortex, and the brain stem). SCD is classified into two types: 1) paraneoplastic cerebellar degeneration, which sometimes accompanies a cancer diagnosis, and 2) alcoholic or nutritional cerebellar degeneration, which is caused by a shortage of vitamin B-1 (thiamine). These two categories have similar symptoms but not the same underlying cause.

1. Diagnosis and treatment of the underlying cancer are standard therapeutic treatments for paraneoplastic cerebellar degeneration. Prompt tumor excision, chemotherapy, and/or radiation may be effective and help patients lessen discomfort.
2. Adjuvant glucocorticoid therapy, such as methylprednisolone, and immunotherapy with effective T cell suppression, such as rituximab and tacrolimus, may be difficult to achieve. However, in isolated cases, both rituximab and tacrolimus have been reported to help stabilize symptom progression in individuals with paraneoplastic cerebellar degeneration.
3. Thiamine is given combined with other B vitamins to treat alcoholic/nutritional cerebellar degeneration, and usually relieves the disease if the patient quits consuming alcohol and resumes a normal diet.
4. Physical treatment with an emphasis on strength, balance, and gait balance can assist individuals with increasing symptoms to regain function and avoid long-term disability.
5. Occupational therapy can focus mostly on activities of daily life and dysphagia rehabilitation.

Weakened muscle coordination, Problems in the articulation of speech,Difficulty in swallowing,Diplopia,Dizziness,Tremors,Problems with cognitive and emotional regulation
Thiamine supplements

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