From the Guidelines
Yes, Neurodegeneration with Brain Iron Accumulation (NBIA) can cause visual loss. NBIA is a group of rare genetic disorders characterized by iron accumulation in the brain, particularly in the basal ganglia. Visual impairment in NBIA typically occurs due to retinal degeneration or optic nerve atrophy. The most common visual manifestation is retinitis pigmentosa, which causes progressive vision loss beginning with night blindness and peripheral vision loss, potentially advancing to severe visual impairment. Some NBIA subtypes, particularly Pantothenate Kinase-Associated Neurodegeneration (PKAN), are more strongly associated with visual problems. There is no specific treatment to reverse the visual loss in NBIA, but supportive care including regular ophthalmologic evaluations, visual aids, and low-vision rehabilitation can help manage symptoms. The visual symptoms occur because the same genetic mutations that cause iron accumulation in the brain can also affect the retina and optic nerve, disrupting normal visual processing pathways. Key diagnostic features of NBIA can be identified using MRI of the brain without IV contrast, including susceptibility-weighted sequences, as recommended by the American College of Radiology 1. This imaging modality is optimal for patients with suspected NBIA due to its soft-tissue characterization and sensitivity to iron deposition. Regular monitoring and supportive care can help improve the quality of life for patients with NBIA, despite the lack of a cure for the visual loss associated with this condition. In clinical practice, it is essential to prioritize the diagnosis and management of NBIA, considering the potential for visual loss and other systemic complications, to minimize morbidity and mortality, and optimize the patient's quality of life. The use of MRI and other diagnostic tools, as outlined in the acr appropriateness criteria® movement disorders and neurodegenerative diseases 1, can facilitate early detection and treatment of NBIA-related visual impairment. By prioritizing timely diagnosis and supportive care, clinicians can help mitigate the impact of visual loss on patients with NBIA, ultimately improving their overall quality of life.
From the Research
Neurodegeneration with Brain Iron Accumulation (NBIA) and Visual Loss
- NBIA is a heterogeneous group of progressive neurodegenerative diseases characterized by iron deposition in the brain, and it can present with a wide spectrum of clinical symptoms, including ocular abnormalities 2, 3.
- The clinical spectrum of NBIA includes visual disorders, and patients with atypical form of NBIA type I have been found to have functional retinal changes associated with marked instability of ocular fixation 4.
- Visual and ocular motor function can be affected in patients with NBIA, with symptoms such as unstable ocular fixation, low gain pursuit, hypermetric saccades, and caloric and rotatory responses 4.
- NBIA disorders can also present with visual dysfunction, in addition to hypo- and/or hyperkinetic movement disorders and other neurological symptoms 5.
- While the exact mechanisms of visual loss in NBIA are not fully understood, it is thought to be related to the accumulation of iron in the brain and the resulting damage to brain tissue 6.