Paraneoplastic cerebellar degeneration
- Characterized by subacute, progressive ataxia, dysarthria, and nystagmus.
- Myoclonus, opsoclonus (irregular jerking of the eyes in all directions), diplopia, vertigo, and hearing loss may also occur.
- Most common associated tumor types: small cell carcinoma of the lung, ovarian/breast carcinoma, and lymphoma.
- Anti-Purkinje cell antibodies (anti-Yo antibodies) may be present in 50%.
- May precede symptoms of the underlying tumor itself.
Hypercalcemia
- May result from parathyroid-related peptide secreted by the tumor (usually lung cancer) or bone destruction by metastatic disease.
- Elevated serum calcium decreases membrane excitability, leading to clinical syndrome of fatigability, lethargy, generalized weakness, and areflexia progressing to coma and convulsions.
- Symptoms usually occur when levels reach 14 mg/dL (3 mmol/l) or higher.
Lambert-Eaton myasthenic syndrome (LEMS)
- Shows subacute proximal muscle weakness and spares the bulbar musculature.
- Due to presynaptic blockade of voltage-gated calcium channels by autoantibodies.
- Characteristic feature: brief increase in strength after repeated muscle activation.
- Most cases associated with small cell lung cancer or other autoimmune diseases.
Paraproteinemic neuropathy
- Polyneuropathy may occur in up to 15% of patients with multiple myeloma.
- Presents as chronic distal symmetrical sensory or sensorimotor neuropathy.
- CSF protein may be elevated, resembling chronic inflammatory demyelinating polyneuropathy.
- Up to 20% of patients referred for evaluation of polyneuropathy may have monoclonal gammopathy of undetermined significance, which may later declare itself as a hematologic malignancy.
Made with Bullet