Neuroblastoma is a cancer primarily affecting young children. This type of cancer develops from immature nerve cells called neuroblasts. While it often originates in the adrenal glands, located atop the kidneys, it can also develop in nerve tissue found in the chest, abdomen, or pelvis. Eye-related symptoms frequently serve as an early and noticeable indicator of neuroblastoma, often prompting medical evaluation.
How Neuroblastoma Manifests in the Eyes
One recognizable sign of neuroblastoma affecting the eyes is periorbital ecchymosis, or “raccoon eyes.” This involves dark circles or bruising around the eyes. This bruising often results from tumor metastasis to the bones surrounding the eyes, specifically the orbital bones. The deposition of blood in the eyelids can sometimes lead to confusion with traumatic injury.
Another symptom is proptosis, where one or both eyes bulge forward. This occurs when a tumor grows behind the eyeball, pushing the eye outwards.
Opsoclonus-Myoclonus Syndrome (OMS) presents as “dancing eyes,” characterized by rapid, involuntary eye movements. These erratic eye movements are frequently accompanied by myoclonus, which are brief, shock-like muscle jerks, and ataxia, an unsteady gait. OMS is a paraneoplastic syndrome, arising from the body’s immune system reacting to the tumor rather than direct tumor invasion.
Other signs of neuroblastoma involving the eyes include unequal pupil size (anisocoria) or a drooping eyelid (ptosis). These signs can indicate nerve involvement.
Understanding the Connection: Why Neuroblastoma Affects the Eyes
Neuroblastoma affects the eyes through distinct mechanisms, primarily direct tumor spread and an immune-mediated response. Direct tumor metastasis occurs when neuroblastoma cells travel from their original site, such as the abdomen, through the bloodstream or lymphatic system. These circulating cells can establish new tumors in the orbital bones surrounding the eye or directly behind the eyeball. This direct invasion explains “raccoon eyes” and proptosis.
In contrast, OMS is a paraneoplastic syndrome, an autoimmune response to the tumor. In this scenario, the body’s immune system mistakenly attacks healthy brain tissue, particularly parts of the cerebellum and brainstem. This misdirected attack happens because these healthy brain tissues share similarities with proteins produced by the neuroblastoma cells. The resulting immune reaction leads to neurological symptoms, including “dancing eyes.” With OMS, the tumor is not directly located in the brain affecting the eyes; rather, the immune system’s response to the tumor causes these symptoms.
Diagnosis and Management of Ocular Neuroblastoma
Diagnosing neuroblastoma with ocular involvement begins with a thorough clinical examination, where a doctor assesses any visible eye signs or neurological symptoms. Imaging studies, such as MRI and CT scans, are then used to visualize potential tumors, determine their size, and check for any spread to the eye orbits or other body areas.
A biopsy is often necessary to confirm the diagnosis of neuroblastoma, which may involve a bone marrow biopsy or a direct tumor biopsy. Urine tests are also frequently performed to detect elevated levels of catecholamine metabolites, such as vanillylmandelic acid (VMA) and homovanillic acid (HVA), which are often produced by neuroblastoma cells. A specialized nuclear medicine scan, a metaiodobenzylguanidine (MIBG) scan, can also detect neuroblastoma cells throughout the body.
The management of ocular neuroblastoma typically involves a multidisciplinary team of specialists. This team usually includes pediatric oncologists, ophthalmologists, and neurologists. Common treatment modalities include chemotherapy to shrink tumors, surgery to remove the primary tumor, and radiation therapy. The specific treatment approach is tailored to the tumor’s stage, its location, and other risk factors. For cases involving Opsoclonus-Myoclonus Syndrome, specific treatments like immunosuppressive therapy, such as corticosteroids or intravenous immunoglobulin (IVIG), are administered in addition to cancer treatment to manage the autoimmune response. The overall goal of treatment is not only to eradicate the cancer but also to preserve vision and maintain eye function.