Paraneoplastic Cerebellar Degeneration (PCD)

What is Paraneoplastic Cerebellar Degeneration?

Paraneoplastic cerebellar degeneration (PCD) is an immune-mediated injury to the cerebellum, specifically its Purkinje cells, that occurs in people who have or will develop a cancer. The damage is not caused by the tumor spreading to the brain.^[1] It is rare but is one of the more common paraneoplastic neurological syndromes, and it can develop over a few weeks and cause severe disability.^{[1, 2]}

Common symptoms

The typical picture is a rapidly progressive cerebellar syndrome with unsteady walking, poor coordination of the arms and legs, and trouble with speech.^{[2, 3]} Dizziness and abnormal eye movements are also common cerebellar signs.^[4]

• Gait unsteadiness and poor balance
• Clumsy, shaky hand movements
• Slurred speech and sometimes difficulty swallowing
• Dizziness or abnormal eye movements

Symptoms can appear before the cancer is found, sometimes years earlier, which is why continued surveillance is advised.^[2]

Causes and risk factors

PCD occurs when the immune response against a tumor also attacks proteins normally found in cerebellar neurons.^[5] Anti-Yo antibodies are the best-known marker and are usually seen in women with breast or ovarian tumors.^{[3, 4]} Anti-Tr (DNER) antibodies occur in Hodgkin lymphoma, and anti-Hu, anti-Ri and anti-Ma2 antibodies can also be linked to cerebellar or brainstem syndromes.^{[4, 5]} The StatPearls chapter lists breast cancer, pelvic cancers, small cell lung cancer, lymphoma and others as associated tumors.^[1]

The precise mechanisms are still unclear, and the risk of this complication may rise as cancer immunotherapy such as immune checkpoint blockade becomes more common.^{[4, 5]}

How it is diagnosed and treated conventionally

Neurologists diagnose PCD from the clinical syndrome, antibody tests in blood and spinal fluid, and imaging. The 2021 diagnostic criteria help guide the search for the underlying cancer.^{[2, 5]} MRI is often normal early on and shows cerebellar shrinkage later.^[3]

Treatment has two parts. The first is finding and removing or treating the tumor, and the second is immune treatment such as steroids, immunoglobulin, plasma exchange or other immunosuppressants.^[6] Earlier treatment, when there is less cerebellar damage, is linked to a better outlook.^[6] Results are often limited, particularly with anti-Yo antibodies, and many people are left with major disability.^[3] Physical and occupational therapy are part of care for ataxia.^[7]

Why Paraneoplastic Cerebellar Degeneration calls for a whole-person approach

PCD sits at the meeting point of cancer, the immune system and the nervous system, so care normally involves neurology, oncology and rehabilitation teams.^{[2, 5]} Beyond the medical treatment, people deal with falls risk, fatigue, poor sleep and the demands of cancer treatment.

Supportive care is a reasonable addition only once these teams are in charge. The factors below are the areas where it may add comfort.

Balance, movement and rehabilitation

A meta-analysis of therapeutic exercise in cerebellar ataxia found low to moderate certainty evidence of improvements in ataxia severity and balance.^[8] A second review of physiotherapy in degenerative ataxia found low-certainty evidence and called for better trials.^[9] These studies mostly did not involve PCD, so exercise should be planned with your therapist.

The immune response

PCD is driven by the immune system, which is why immune treatments are central.^{[5, 6]} Complementary care does not change this process.

Cancer treatment effects

Pain, nausea, fatigue and insomnia are common during cancer care, and these have been the focus of most supportive-care research.^[10]

Stress and sleep

Cancer-related insomnia is frequent in people with cancer and may add to fatigue and mood problems.^[11]

Acupuncture as supportive care in Paraneoplastic Cerebellar Degeneration

What the research shows

No clinical trials of acupuncture for PCD, or for cerebellar ataxia from any cause, were found in PubMed, so there is no evidence that acupuncture improves balance, coordination or the course of the disease. Acupuncture should never delay or replace cancer treatment, immune treatment or rehabilitation.

For symptoms common in people with cancer, studies in other patients exist. A meta-analysis of 14 trials found acupuncture and acupressure associated with less cancer pain, with moderate-certainty evidence and substantial differences between trials.^[12] A meta-analysis of acupuncture added to usual care for chemotherapy-related nausea and vomiting suggested more complete control of vomiting, but the certainty was low or very low.^[13] A review of cancer-related insomnia found benefit for sleep in several studies, but the trials varied widely and larger ones are needed.^[11] An overview of 51 systematic reviews found acupuncture appeared helpful for cancer fatigue, with most reviews rated low in quality.^[10] These studies were not in PCD.

How acupuncture may work

No study has examined how acupuncture might act on the cerebellum or on an autoimmune attack on it, so we cannot offer a mechanism for PCD. Nothing in the research cited here shows that acupuncture changes the disease process.

What treatment involves

Treatment uses fine, sterile, single-use needles, usually left in place about 20 to 40 minutes. A short course of visits is followed by reassessment. We would begin only with your oncologist's and neurologist's knowledge, and treatment is adjusted around unsteadiness and fall risk.

In prospective studies, about 9 in 100 patients had a minor reaction such as bleeding, pain or redness at a needle site, and serious events occurred in about 1 in 10,000 patients.^[14] Tell the practitioner first if you have low blood counts or a bleeding disorder, take blood thinners, are on chemotherapy or immune-suppressing drugs, or have a pacemaker (relevant to electroacupuncture).

Ayurvedic medicine as supportive care in Paraneoplastic Cerebellar Degeneration

The Ayurvedic view

Ayurveda has no classical name for PCD. Practitioners usually describe loss of balance, tremor and unsteady movement as disturbances of Vata, the principle said to govern movement and the nervous system. These are traditional categories for choosing care, not biomedical diagnoses.

Therapies that may be used

Ayurvedic support is individualized and may include:

• Warm, regular meals and steady sleep hours intended to calm Vata and ease fatigue
• Gentle warm oil massage, avoiding any area affected by cancer treatment such as radiation skin changes
• Relaxation practices such as breathing exercises and gentle seated yoga
• Herbs chosen individually, only after review of your cancer treatment and medicines

Panchakarma, the traditional cleansing program, is not appropriate for people with PCD. They may be acutely ill, frail, receiving chemotherapy or immunosuppressants, or at risk of falls, and it is not appropriate during pregnancy.

What the research shows

No clinical trials of Ayurvedic treatment for PCD were found, and there is no evidence that it changes the disease.

Ashwagandha has been studied for stress and sleep in other adults. A meta-analysis of 12 trials found lower anxiety and stress scores than with placebo, though with low certainty and large differences between trials.^[15] A meta-analysis of 5 trials found a small improvement in sleep, with limited long-term safety data.^[16] Its effect during cancer or immune treatment has not been established, and it should be cleared with your oncologist.

Herbal medicine as supportive care in Paraneoplastic Cerebellar Degeneration

Herbs and formulas that have been studied

No herb or formula has been studied in clinical trials of PCD or cerebellar ataxia from other causes, in what we found. Chinese medicine traditionally uses formulas aimed at balance, tremor and strengthening. We have not found trials that test them for this condition.

What the research shows

There is no research on herbs in PCD, and we do not use herbs aimed at the cancer or the immune attack. Any herbal care would be limited to symptoms such as sleep and stress, and only if your oncology and neurology teams agree.

Safety and herb-drug interactions

Herbal safety is a serious issue in cancer care and in treatment with immune-suppressing drugs. A literature review documents clinically significant interactions between herbs and prescribed drugs, mostly from case reports, including drugs given after transplant.^[17] Case reports describe bleeding when warfarin was combined with herbs including dang gui, dan shen, ginger, ginseng and Boswellia.^[18]

Herbal and dietary supplements account for about 20% of drug-induced liver injury in the United States, which matters if you take treatments that also affect the liver.^[19] About one fifth of Ayurvedic medicines bought online contained detectable lead, mercury or arsenic.^[20] Herbs should come from tested sources and be prescribed individually. Tell us if you are pregnant or breastfeeding or have liver or kidney disease.

Translating traditional medicine into modern biological language

This is interpretation, not equivalence. Chinese medicine might describe unsteadiness and tremor as internal wind or deficiency, and Ayurveda as aggravated Vata. Researchers describe PCD as an immune attack on cerebellar Purkinje neurons, triggered by proteins that tumors share with the brain.^{[1, 5]}

Traditional language about restoring balance has no tested counterpart in PCD, and no study suggests that acupuncture or herbs act on the cerebellum or the autoimmune process.

How this care fits with your medical care

Complementary care is a supplement to your neurologist's and oncologist's treatment, never a substitute. Do not stop or change cancer treatment, steroids, immunoglobulin or any other prescribed medicine without your prescriber. For a condition like this, we ask that you are under a physician's care for it and that your treating team knows you are receiving complementary care.

We do not diagnose or monitor PCD or cancer. Please bring your diagnosis, your cancer type and treatment plan, a list of all medicines and supplements, recent blood counts, and your doctors' contact details.

When to seek urgent medical care

PCD can progress quickly and early treatment matters, so new or worsening neurological symptoms need prompt assessment.^{[1, 6]}

• New or rapidly worsening unsteadiness, falls, or trouble walking
• New slurred speech, double vision, or trouble swallowing or choking
• Sudden severe headache, confusion, or weakness on one side
• Fever, especially while on chemotherapy or immune-suppressing medicine
• Unexplained weight loss, a new lump, or coughing blood
• Thoughts of harming yourself: call or text 988 (Suicide and Crisis Lifeline)

If any of these occur, call 911 or go to the nearest emergency department.