Balint Syndrome

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Disease Entity

Balint syndrome.

Disease

Balint syndrome is a triad of symptoms characterizing a bilateral parieto-occipital lesion:

1. Simultanagnosia – the inability to perceive multiple objects simultaneously.

2. Optic ataxia – the inability to move the hand to objects using visual cues.

3. Oculomotor apraxia – difficulty in fixating gaze and following objects with the eyes.

Historical perspective

Balint syndrome was first described in 1909 by Reszo Balint.[1] The original findings he described included an inability to perceive different items in a visual scene at the same time, an inability to voluntarily shift gaze to a fixation target, and the inability to reach for an object with the right hand but maintained ability to do so with the left hand.[1] Balint originally postulated that the constellation of findings was due to discordance between sensory and motor output.[1] Holmes and Horrax[2] described similar findings in a patient in 1919 but suggested that these deficits were due to visuospatial disturbances alone because the patient had no motor or sensory disturbances. The term “Balint’s syndrome” was not coined until 1954.[3] Today, many studies focus on the neural mechanisms of the individual components that comprise Balint syndrome their rather than the syndrome itself.[4]

Etiology

Balint syndrome most often occurs from bilateral symmetric lesions in the parietal and occipital areas.[5] These lesions are typically due to watershed infarction from cerebral hypoperfusion.[5] Other reported causes include Alzheimer's disease, Creutzfeldt-Jakob disease (CJD), posterior reversible encephalopathy syndrome (PRES), subacute HIV encephalitis, progressive multifocal leukoencephalopathy (PML), primary central nervous system angiitis, cerebral adrenoleukodystrophy, and reversible cerebral vasoconstriction syndrome.[6][7][8][9][10][11][12][13]

Pathophysiology

The mechanisms that underly the features of Balint syndrome are poorly understood. Simultanagnosia may be due to a visual attention deficit due to damage to the visuospatial attention system in the parietal lobe and is associated with lesions in Brodmann’s areas 7, 10, and 39.[5][14] It has also been postulated to be related to defects in visual processing speed.[15]

Despite the term “ataxia”, optic ataxia is not related to cerebellar dysfunction or motor weakness. Isolated optic ataxia is associated with lesions in Brodmann’s areas 5, 7, 19, 39, 37.[16][17] Optic ataxia in Balint syndrome may be associated with disconnection of the occipital lobe from the frontal lobe where the anterior motor centers are located and upper extremity movements are initiated.[17][18] Other explanations include defects in integrating panoramic visual information with upper extremity proprioception and impairments in visuomotor control without impairment of perception.[5][17]Oculomotor apraxia may be due to a disconnection of the occipital lobe from the frontal eye fields or uncertainty about a fixation target’s location.[5] 

Diagnosis

The diagnosis of Balint syndrome is made clinically and is defined by the presence of three key features: (1) simultanagnosia (2) optic ataxia, and (3) oculomotor apraxia. Certain tools can assist in the evaluation of a patient’s symptoms and neuroimaging can identify the underlying etiology.

History

Balint syndrome can be disabling and when severe, patients act as though they are blind due to limited visual and spatial awareness. Patients may describe frequently bumping into objects due to a combination of poor depth and distance perception as well as inability to synthesize their surroundings.[14] Patients may also have difficulty eating and drinking due to the inability to reach for and grasp objects (optic ataxia). Reading may also be a challenge, as some patients perceive letters individually and have difficulties grouping them into words (simultanagnosia).[19]

Physical examination

Simultanagnosia is the inability to visually recognize more than one object at a time. The patient can identify individual items in a complex visual display but cannot grasp multiple items and their relation to the broader display. A classic example is a patient’s inability to recognize a picture of a forest despite recognizing the trees within it (literally missing the forest for the trees).

Optic ataxia is the inability to accurately point to or reach for objects under visual guidance with intact ability when directed by sound or touch despite normal strength. Therefore, a patient who can see an object may be unable to reach for it accurately until they physically contact it. 

Oculomotor apraxia is the inability to shift gaze voluntarily without any evidence of extraocular muscle paralysis. Patients with oculomotor apraxia are unable to produce voluntary saccades, but involuntary reflexive saccades are intact. Balint first described this finding as “psychic paralysis of gaze” and was later described as “spasm of fixation” by Holmes.[1][2] While optic ataxia and simultanagnosia are often reported independently, oculomotor apraxia is typically associated with either optic ataxia or simultanagnosia.[14] Patients with Balint syndrome may also have an absent blink to threat response and bilateral inferior altitudinal visual field defects.[2][20] 

Diagnostic procedures

While no specific diagnostic criteria exist for Balint syndrome, certain tools can be used to elucidate symptoms. Asking patients to interpret complex scenes such as the “Boston Cookie Theft” and the “Telegraph Boy” can reveal symptoms of simultanagnosia.[21][22]Patients will identify individual items in the picture but cannot correctly interpret what is happening in the scene. Patients will also have difficulty interpreting Ishihara color plates, which require combining colored dots into a larger number.[23] However, this is not due to color vision abnormalities, as patients will be able to correctly identify the individual colors on the plate.[23] If the three cardinal features of Balint syndrome are identified together or in isolation, this may warrant further neurologic evaluation with neuroimaging, and the ophthalmologist should consider referral to neurology for a more complete workup. There are no defined diagnostic criteria for imaging studies in Balint syndrome, but findings will be consistent with the underlying etiology. Non-contrast computed tomography (CT) of the head is usually the best initial test to rule out intracranial hemorrhage. Magnetic resonance imaging (MRI) may reveal bilateral damage to the parietal and occipital lobes due to ischemia, hemorrhage, neoplasm, or cortical atrophy. Single-photon emission computed tomography (SPECT) may show decreased cerebral perfusion.

Differential diagnosis

Hemispatial neglect, a condition affecting awareness of one side of the body or environment, may present similarly to Balint syndrome and the two may be present simultaneously.[16] Patients with hemispatial neglect may have defects in visual search mimicking ocular apraxia and defects in hand movement with visual guidance similar to optic ataxia. Patients may also experience “extinction” of objects in the neglected hemifield when objects are present in both fields resembling simultanagnosia.[16] The lesions in Balint syndrome, however, are bilateral and affect the parieto-occipital junction, whereas the lesions in hemispatial neglect typically affect the temporo-parietal junction on the right side. An extensive lesion in the parietal lobes may lead to both Balint syndrome and hemispatial neglect.[1][16]

Management

The management of Balint syndrome begins with addressing the underlying etiology and employing secondary preventive measures. Beyond this, treatment is centered on rehabilitation and adaptive strategies to reduce disability. Neuropsychological rehabilitation strategies include restoration which works by training the impaired function and therefore the damaged part of the brain, and compensation, which refers to improving an intact function to compensate for the loss of another.[24] Most rehabilitation regimens in Balint syndrome are multifaceted, but compensatory strategies have appeared to be the most beneficial.[24] Some studies, however, have employed the restorative approach by using eye movement or convergence exercises which is sometimes successful.[24]

Prognosis

The prognosis of patients with Balint syndrome is variable and depends on the underlying etiology. Acute causes such as infectious or cerebrovascular etiologies may carry a good prognosis if managed appropriately. However, progressive neurodegenerative etiologies such as Alzheimer’s or posterior cortical atrophy typically have a poor prognosis. Rehabilitation, however, is possible in most patients with Balint syndrome and many regain some functional capabilities and an improved quality of life.[24]

References

  1. 1.0 1.1 1.2 1.3 1.4 Bálint, Dr. R. Seelenlähmung des “Schauens”, optische Ataxie, räumliche Störung der Aufmerksamkeit. pp. 51–66. Eur Neurol. 1909;25(1):51-66. doi:10.1159/000210464
  2. 2.0 2.1 2.2 HOLMES G. DISTURBANCES OF SPATIAL ORIENTATION AND VISUAL ATTENTION, WITH LOSS OF STEREOSCOPIC VISION. Arch Neurol Psychiatry. 1919;1(4):385. doi:10.1001/archneurpsyc.1919.02180040002001
  3. HÉCAEN H, de AJURIAGUERRA J. BALINT’S SYNDROME (PSYCHIC PARALYSIS OF VISUAL FIXATION) AND ITS MINOR FORMS. Brain. 1954;77(3):373-400. doi:10.1093/brain/77.3.373
  4. Moreaud O. Balint Syndrome. Arch Neurol. 2003;60(9):37-39. doi:10.1001/archneur.60.9.1329
  5. 5.0 5.1 5.2 5.3 5.4 Pelak VS. Disorders of Higher Cortical Visual Function. Third Edit. Elsevier Inc.; 2019. doi:10.1016/b978-0-323-34044-1.00009-2
  6. Hof PR, Bouras C, Constantinidis J, Morrison JH. Balint’s syndrome in Alzheimer’s disease: specific disruption of the occipito-parietal visual pathway. Brain Res. 1989;493(2):368-375. doi:10.1016/0006-8993(89)91173-6
  7. Ances BM, Ellenbogen JM, Herman ST, et al. Balint syndrome due to Creutzfeldt-Jakob disease. Neurology. 2004;63(2):395-395. doi:10.1212/01.WNL.0000130339.37477.54
  8. Kumar S, Abhayambika A, Sundaram ANE, Sharpe JA. Posterior reversible encephalopathy syndrome presenting as balint syndrome. J Neuro-Ophthalmology. 2011;31(3):224-227. doi:10.1097/WNO.0b013e31821b5f92
  9. Berger JR, Whigham TE. Balint’s syndrome in subacute HIV encephalitis. J Neurol Neurosurg Psychiatry. 1993;56(1):115-115. doi:10.1136/jnnp.56.1.115
  10. Ayuso-Peralta L, Jiménez-Jiménez FJ, Tejeiro J, et al. Progressive multifocal leukoencephalopathy in HIV infection presenting as Balint’s syndrome. Neurology. 1994;44(7):1339-1340. doi:10.1212/wnl.44.7.1339
  11. Jacobs DA, Liu GT, Nelson PT, Galetta SL. Primary central nervous system angiitis, amyloid angiopathy, and Alzheimer’s pathology presenting with Balint’s syndrome. Surv Ophthalmol. 49(4):454-459. doi:10.1016/j.survophthal.2004.04.002
  12. Uyama E, Iwagoe H, Maeda J, Nakamura M, Terasaki T, Ando M. Presenile-onset cerebral adrenoleukodystrophy presenting as Balint’s syndrome and dementia. Neurology. 1993;43(6):1249-1249. doi:10.1212/WNL.43.6.1249
  13. Walsh RD, Floyd JP, Eidelman BH, Barrett KM. Bálint syndrome and visual allochiria in a patient with reversible cerebral vasoconstriction syndrome. J Neuroophthalmol. 2012;32(4):302-306. doi:10.1097/WNO.0b013e3182359f4a
  14. 14.0 14.1 14.2 Chechlacz M. Bilateral Parietal Dysfunctions and Disconnections in Simultanagnosia and Bálint Syndrome. Vol 151. 1st ed. Elsevier B.V.; 2018. doi:10.1016/B978-0-444-63622-5.00012-7
  15. Neitzel J, Ortner M, Haupt M, et al. Neuro-cognitive mechanisms of simultanagnosia in patients with posterior cortical atrophy. Brain. 2016;139(12):3267-3280. doi:10.1093/brain/aww235
  16. 16.0 16.1 16.2 16.3 Rizzo M, Vecera SP. Psychoanatomical substrates of Bálint’s syndrome. J Neurol Neurosurg Psychiatry. 2002;72(2):162-178. doi:10.1136/jnnp.72.2.162
  17. 17.0 17.1 17.2 Damasio AR, Benton AL. Impairment of hand movements under visual guidance. Neurology. 1979;29(2):170-178. doi:10.1212/wnl.29.2.170
  18. Nagaratnam N, Grice D, Kalouche H. Optic ataxia following unilateral stroke. J Neurol Sci. 1998;155(2):204-207. doi:10.1016/S0022-510X(97)00301-8
  19. Baylis GC, Driver J, Baylis LL, Rafal RD. Reading of letters and words in a patient with Balint’s syndrome. Neuropsychologia. 1994;32(10):1273-1286. doi:10.1016/0028-3932(94)90109-0
  20. Liu GT, Ronthal M. Reflex blink to visual threat. J Clin Neuroophthalmol. 1992;12(1):47-56. http://www.ncbi.nlm.nih.gov/pubmed/1532602.
  21. KINSBOURNE M, WARRINGTON EK. A DISORDER OF SIMULTANEOUS FORM PERCEPTION. Brain. 1962;85(3):461-486. doi:10.1093/brain/85.3.461
  22. Jackson GM, Shepherd T, Mueller SC, Husain M, Jackson SR. Dorsal Simultanagnosia: an Impairment of Visual Processing or Visual Awareness? Cortex. 2006;42(5):740-749. doi:10.1016/S0010-9452(08)70412-X
  23. 23.0 23.1 Brazis PW, Graff-Radford NR, Newman NJ, Lee AG. Ishihara color plates as a test for simultanagnosia. Am J Ophthalmol. 1998;126(6):850-851. doi:10.1016/S0002-9394(98)00187-1
  24. 24.0 24.1 24.2 24.3 Heutink J, Indorf DL, Cordes C. The neuropsychological rehabilitation of visual agnosia and Balint’s syndrome. Neuropsychol Rehabil. 2019;29(10):1489-1508. doi:10.1080/09602011.2017.1422272