About Paraneoplastic Neurological Disorders (PND) > Central Nervous System (Brain and Spinal Cord) > Paraneoplastic Cerebellar Degeneration (PCD)

Paraneoplastic Cerebellar Degeneration (PCD)

Patients with this PND develop severe problems in performing fine and smooth movements of the arms, legs, and muscles that control the eyes, speech and swallowing. The movements appear to be fragmented and sometimes made worse by tremor.

For example, when the patient tries to reach for an object with one hand, the movement “overshoots” the location of the object, having to correct it in order to finally reach it. If the patient can walk, the gait is unsteady, like a person who is drunk. In most cases the unsteadiness makes it impossible to walk.

Due to problems controlling the movement of the eyes, patients develop double vision or a sensation of “jumpiness” of the vision so that tasks such as reading or watching TV can be difficult or impossible. Simple chores like writing, feeding oneself, or dressing can become impossible to perform.

Although the spinal fluid of these patients is usually abnormal, the brain MRI is often normal at the time the symptoms present. Several weeks or months after the neurological symptoms appear the MRI shows atrophy of the cerebellum (Figure 1). There are a number of antibodies and tumors that are associated with paraneoplastic cerebellar degeneration (see Table and Figure 2).

Paraneoplastic cerebellar degeneration is one of the PND that is most difficult to treat. Although some patients may notice mild improvement after treatment of the tumor and immunotherapy (see below in section General Comments on Treatment), most patients do not improve. At best, treatment may result in stabilizing symptoms. In very rare instances, dramatic improvement occurs.

Table: Antibodies associated with paraneoplastic cerebellar degeneration (PCD)

Antibodies that predominantly associate with PCD


Predominant Syndrome

Associated Cancers



Ovary, breast



Hodgkin’s lymphoma



Hodgkin’s lymphoma




Antibodies that may associate with PCD



SCLC, lymphoma

Anti-Hu (ANNA-1)

Encephalomyelitis, PCD, sensory neuronopathy

SCLC, other

Anti-Ri (ANNA-2)

PCD, brainstem encephalitis, opsoclonus-myoclonus

Breast, gynecological, SCLC


Encephalomyelitis, PCD, chorea, peripheral neuropathy

SCLC, thymoma, other

Anti-Ma proteins***

Limbic, hypothalamic, brainstem encephalitis (infrequently PCD).

Testis, lung cancer, other


Stiff-person syndrome, encephalomyelitis, PCD

Breast, SCLC

mGluR1: metabotropic glutamate receptor 1; Zic 4: zinc-finger of the cerebellum 4; VGCC: voltage-gated calcium channel

*Anti-mGluR1 antibodies have been identified in only two patients.

**Anti-Zic4 antibodies predominantly associate with PCD only when no other paraneoplastic antibodies are detectable.

***Ma proteins include Ma2 and Ma1. Patients with brainstem and cerebellar dysfunction usually harbor antibodies against both, Ma1 and Ma2.

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