BRAIN INJURY , 2001, VOL. 15, NO. 4, 363± 370 Case study Altitudinal neglect in a patient with occipital infarction A L I C E E R G U N - M A R T E R E R y, E R D E M E R G U N z, M U S T A F A M E N T E S } a n d WALTER ODERy y Rehabilitation Centre for Head Injury Patients, Meidling, AUVA, Vienna, Austria z Department of Ophthalmology, University of Vienna, Vienna, Austria } Department of Radiodiagnostics, University of Vienna, Vienna, Austria (Received 26 October 1999; revised 4 July 2000; accepted 28 July 2000 ) Visual neglect has been frequently described in a horizontal direction. Altitudinal neglect, however, has rarely been described and has been associated with bilateral lesions in the parieto-occipital or temporo-occipital region. The following case report presents a patient with marked altitudinal neglect of the inferior space which was elicited using a line bisection test. The previously healthy patient had well-defined lesions solely in the occipital cortex following an embolic infarction. The present case report underlines the possibility that bioccipital lesions themselves can be responsible for altitudinal neglect. Case report A 27-year-old, hitherto healthy female suffered a bioccipital infarction of embolic origin following an arthroscopic procedure. Arthroscopy of the left knee was performed due to a ruptured anterior crucial ligament following a skiing accident. Cranial magnetic resonance imaging (MRI) 4 days post-infarction showed hyperintensity. This was primarily in the right occipital lobe (in part the forceps major, lingual gyrus, rostral portion of the cuneus and occipital white matter) and the rostral part of the right cingulate gyrus and isthmus. It was also, to a lesser extent, in the left occipital lobe (rostral portion of the cuneus and lingual gyrus) and rostral part of the left cingulate gyrus. Two small hyperintense lesions were seen in the right pulvinar thalami. On presentation to the rehabilitation centre 11 months post-infarction, the patient claimed to have repeatedly `overlooked’ objects in her lower visual field. She had frequently fallen over her 5-year-old son (105 cm) when he stood in front of her, and was hitting the bedpost in her home regularly while walking by. Computer perimetry (threshold testing with 30/2 program, Humphrey Field Analyser, Allergan Humphrey, San Leandro, CA) revealed isolated scotomas of the left upper quadrant and, to a far lesser degree, of both lower quadrants. The central visual field and the area between 5± 7 o’clock was free (figure 1). Although there was Correspondence to: Professor Walter Oder, MD, Rehabilitation Centre for Head Injury Patients, Meidling, AUVA, Koeglergasse 2a, A-1120 Vienna, Austria. e-mail: walter.oder@auva.sozvers.at Brain Injury ISSN 0269± 9052 print/ISSN 1362± 301X online # 2001 Taylor & Francis Ltd http://www.tandf.co.uk/journals DOI: 10.1080/02699050010004644 364 A. Ergun-Marterer et al. Figure 1. Computer perimetry left eye, right eye (threshold testing with 30/2 program, Humphrey Field Analyser, Allergan Humphrey, San Leandro, CA), revealing isolated scotomas of the left upper and both lower quadrants. Figure 2. Line bisection stimuli ((a) horizontal plane, (b) vertical plane); in relation to the subject’s head/eyes. some visual field defect, it seemed not marked enough to explain the patient’s comlex complaints, especially because the central visual field and the median part of the lower visual field were not affected. Therefore, a line bisection test for neglect, following the method of Schenkenberg et al. [1], was done on a DIN A4-paper with 20 parallel lines of varying length (94± 192 mm). The midpoint of each line had to be marked with a pencil four times each in the horizontal and vertical plane. As the patient was sitting at a table, keeping her head bent over the test, the horizontal line bisection test investigated horizontal dimension, and the vertical line bisection test altitudinal dimension (figure 2). Thereafter, the patient determined the midpoint of four sticks of balsa-wood (diameter 0.5 cm, length between 22± 56 cm), which were put 30 cm in front of her on a table, approximately centred to the body axis [2]. The sticks were presented one-by-one, randomly, first five times horizontally (testing the horizontal dimension), then vertically (testing the radial dimension) and in an upright position (testing the altitudinal dimension) (figure 3). In this test, the patient was asked to show the midline with a thin marker; the exact measurement was taken immediately after each performed task, but without letting the patient know her result. Altitudinal neglect Figure 3. 365 Stick bisection stimuli ((a) horizontal plane; (b) vertical plane; (c) upright position) in relation to the subject’s head/eyes. Table 1. Line bisection applied to the patient and six controls in the horizontal plane and vertical plane, testing the horizontal and altitudinal dimension; the percentage of lines bisected left to, right to, above, below or exactly at midpoint is listed as well as the mean, maximum and SD (%) to each side. n ˆ total number of lines bisected Left-to-midpoint max deviation mean deviation SD Right-to-midpoint max deviation mean deviation SD At midpoint Horizontal plane …n ˆ 80† (horizontal dimension) Vertical plane …n ˆ 80† (altitudinal dimension) Patient Controls Patient Controls 36.3% 17.4% 4.8% 2.4 41.3% 15.8% 5.7% 2.2 22.4% 44.4% 17.7% 3.6% 2.5 31.3% 14.6% 3.5% 2.3 24.3% 90.0% 18.6% 8.6% 3.9 5.0% 8.3% 3.6% 3.3 5.0% 49.4% 13.8% 4.4% 3.2 26.5% 12.3% 3.4% 2.6 24.1% Above midpoint max deviation mean deviation SD Below midpoint max deviation mean deviation SD At midpoint In the line bisection and stick bisection test, each line and stick bisected was measured with a millimetre ruler. The total amount of all instances of lines and sticks, respectively, which were misbisected to the left or to the right of the exact midpoint, or which were bisected exactly at the midpoint was calculated (in percentage; tables 1 and 2). The percentage of deviation to the left or to the right of the exact midpoint was also calculated for each line and stick individually (`max deviation’, `mean deviation’ and `SD’ in tables 1 and 2). Test results were compared with those of six age-matched healthy controls (four females, two males, mean age 33:5 § 2:2 years). When bisecting vertical lines, the patient placed the marks clearly above the true midpoint in 90% of instances. Comparable results were found in bisecting the upright sticks. Remarkably, the patient bisected nearly two thirds of the sticks placed horizontally too far to the right when compared to the controls. Other tests for visual inattention (cancellation tasks, free-hand drawing, copying of complex figures, visual scanning, picture description) [3] revealed no impairment. The patient also underwent a full neuro-ophthalmological work-up. This revealed an acquired blue-yellow (tritanopic) colour vision deficiency, which was tested using the Farnsworth Munsell D15 desaturated test (Luneau Ophthalmologique, Paris, France). Furthermore, a reduced contrast sensitivity Left-to-midpoint max deviation mean deviation SD Right-to-midpoint max deviation mean deviation SD At midpoint 20.0% 7.7% 5.0% 1.9 65.0% 8.6% 4.4% 2.1 15.0% 40.0% 4.5% 1.5% 1.2 44.2% 3.2% 1.7% 0.9 15.8% Beyond midpoint max deviation mean deviation SD Below midpoint max deviation mean deviation SD At midpoint 50.0% 9.2% 3.8% 2.2 35.0% 9.3% 4.9% 3.0 15.0% 56.7% 13.2% 3.4% 2.6 32.5% 8.4% 1.8% 1.8 10.8% Controls Patient Patient Controls Vertical plane …n ˆ 20† (radial dimension) Horizontal plane …n ˆ 20† (horizontal dimension) Above midpoint max deviation mean deviation SD Below midpoint max deviation mean deviation SD At midpoint 85.0% 15.4% 7.2% 4.2 5.0% 5.4% 5.4% 0.0 10.0% Patient 64.2% 11.5% 3.6% 2.7 29.2% 5.7% 1.7% 1.4 6.7% Controls Upright position …n ˆ 20† (altitudinal dimension) Table 2. Stick bisection applied to the patient and six controls with sticks in the horizontal plane, testing horizontal dimension, lying vertically, testing radial dimension, and standing upright, thereby testing altitudinal dimension; the percentage of sticks bisected left to, right to, beyond, above, below or exactly at midpoint is listed as well as the mean, maximum and SD (%) to each side. n ˆ total number of sticks bisected 366 A. Ergun-Marterer et al. Altitudinal neglect Figure 4. 367 Cranial MRI at the time of testing, demonstrating residual hyperintensity of the right occipital cortex. was found (Vision Contrast Test System, Vistech Consulting Inc., Dayton, OH). Additionally, a discrete impairment of the patient’s stereopsis was elicited using the Titmus stereotest. The patient achieved a stereopsis angle of 200 sec at 45 cm testing distance (norm 40 sec). Gross stereo vision was unimpaired. The neurological, neuropsychological and cardiological work-up, as well as laboratory tests for coagulation anomalies, were unremarkable. A cranial MRI done at the time of testing showed residual hyperintensity of the right occipital cortex including the cingulate gyrus and cuneus partially. All other affected areas had resolved (figure 4). Conclusion Perception of space is based on sensory information which helps in the building of spatial maps. In the body-centred frame, the centre of the spatial coordinate system is the viewer himself [4]. Spatial location is defined relative to the viewer, as being above or below (i.e. altitudinal direction, if the person’s head is in an upright position), right or left (horizontal direction), and near or far (radial direction). 368 A. Ergun-Marterer et al. Patients who manifest neglect fail to report, respond to or orient to stimuli in specific locations of space. Spatial neglect refers to a patient’ s unawareness of and/or failure to act on certain aspects of the environment. Visual neglect in the horizontal plane has been frequently described; neglect of the left hemisphere is commonly associated with right-sided lesions, whereas right neglect after left hemisphere damage occurs occasionally [2, 4± 9]. The patient’ s complaints of not being aware of objects in her lower visual field, together with the bisection test results presented suggest the existence of an altitudinal neglect of the inferior space. Although the patient had a profound visual field defect, the visual field between 5± 7 o’clock showed no scotoma and, therefore, cannot account for the patient’ s complaints and the pathological test results in the bisection tests. If the lower visual field defects were responsible for a shift in line and stick bisection, deviations towards the defects (hence downwards) would be the rule [10]. However, in this patient, the deviations in the vertical line bisection test and in upright sticks were away from the lower hemifield, indicating a neglect of the lower hemispace. Patients suffering from neglect show a deviation of their `egocentric’ visual midline towards the unimpaired side, while patients with hemianopia show a shift of the visual midline towards the scotoma, which is just the opposite bisection error [10]. The controls also misbisected vertical lines slightly above, and radial lines slightly beyond the centre, a finding consistent with other reports in literature [4]. Altitudinal neglect has rarely been described. Rapcsak et al. [2] reported a patient with bilateral parieto-occipital infarctions, who misbisected vertical rods above their true midpoint, indicating altitudinal neglect of the lower visual field. Shelton et al. [9] investigated a patient with bilateral temporo-occipital lesions who misbisected vertical lines significantly below their true midpoint, which was ascribed to altitudinal neglect of the upper visual field. Bilateral lesions of the parieto-occipital region were, thus, suggested to be responsible for neglect of inferior vertical and near radial (peripersonal) space, defined as the space within arm’s reach, while bilateral temporo-occipital injury has been associated with neglect of superior and far (extrapersonal) space, which was defined as the space beyond arm’s reach [4, 7± 9]. Contrary to these authors, one did not see any radial neglect according to vertical stick bisection. Horizontal stick bisection in the patient, however, indicates a discrete left horizontal neglect. Mesulam [12] suggested the existence of an integrated network for the modulation of directed attention within extrapersonal space. Experiments in macaque monkeys showed that the area in the dorsal portion of the inferior parietal lobule (PG) has sensory, limbic, reticular and motor connections. The cingulate cortex and the frontal eye fields are two cortical areas that provide pivotal connections for the dorsolateral PG. They are reciprocally connected with each other as well as with the PG. The frontal eye fields and surrounding regions seem to provide a stage of efferent integration for the initiation and inhibition of motor mechanisms involved in exploratory or attentive behaviour. The cingulate cortex, directing limbic projections predominantly to PG, is thought to participate in directed attention by regulating the spatial distribution of expectation and by assigning impact value to motivationally relevant events. While the basic forebrain may be concerned with a limited set of basic reinforcements such as food or drink, the cingulate cortex may subserve the more complex aspects of reinforcement and their modification by learning. The limbic connections and their convergence with Altitudinal neglect 369 extensively processed sensory afferents may play a fundamental role in assigning motivational valence to complex events that occur within extrapersonal space. The reticular formation provides the level of vigilance. In humans, a cerebral network with similar organization as in the macaque monkey may be responsible for the coordination of directed attention within extrapersonal space [12]. The area PG corresponds to the human right inferior parietal lobe. The intimate connection among parietal, frontal, cingulate and reticular regions, which hold a pivotal role in directed attention, raises the possibility that lesions not only in the parietal lobe, but also in the cingulate cortex, in the frontal eye fields and in reticular structures may disrupt the process of directed attention. Cingulate neglect would, therefore, impair the distribution of expectancy for potential events and also the attribution of motivational relevance to actual stimuli. This holds true for the patient presented who hit the bedpost of her bed regularly while walking by, although she had been living in her home for years before the onset of neglect. She fell over her son repeatedly, although she knew he was around her. The expectancy for the bedpost and her son seems to be impaired. The cuneus and the cingulate gyrus were affected on both sides, which gives further evidence for visual function and for directed attention of these regions [13]. These lesions seem to play an important role in producing altitudinal neglect. The unremarkable results in the other tests for visual attention, which were partially target cancellation tests, exclude an impairment of motor exploration, which is a frontal function. Lateral shift on the line bisection test, on the other hand, has been interpreted as a representational deficit. Binder et al. [14] differentiated between patients with posterior lesions, who performed abnormally in line bisection and normally on cancellation tasks, as opposed to patients with frontal lesions. The MRI performed 4 days post-infarction revealed lesions in both occipital hemispheres. At the time of investigation, 11 months later, the MRI performed showed a residual hyperintensity of the right occipital cortex, while all other affected areas had resolved. This explains the scotoma of the left upper and left lower quadrant of the visual field. However, as there is an additional visual field defect of the right lower quadrant, a functional deficit of the left occipital lobe has to be assumed. In the acute phase, two small hyperintense lesions were seen in the right pulvinar thalami, which were not seen in the MRI 11 months later. According to Robinson and Petersen [11], the pulvinar has a role in attention. It contributes to the determination of salient visual stimuli while acting as a filter of irrelevant and distracting information; it is also of importance in saccadic eye movements. However, humans with thalamic damage have no visual neglect or visual field defects, but show deficits in their ability to use attention to improve visual processing in the contralateral visual field [11]. These data are in contrast to the deficits of the patient presented. The saccadic eye movements were normal and psychologically no impairment in reaction times was seen. The acquired blue± yellow colour deficiency correlates well with the posterior lesions of both cerebral hemispheres. A striking incidence of acquired colour vision defects in patients with bilateral upper quadrant visual field defects has been pointed out by Meadows [15]. The contrast sensitivity reduction can also be interpreted as due to the occipital lesion [16]. Concerning the reduction of stereoscopic vision, a 370 Altitudinal neglect lesion in the right occipital cortex is known to reduce stereopsis more than a lesion of the left side [17]. In conclusion, the present case report of a young, previously healthy patient who had a well-defined bilateral lesion in the occipital region in the acute state of cerebral infarction, and a well defined small lesion in the right occipital region and signs of a functional deficit in the left occipital lobe at the time of investigation shows that bioccipital lesions for themselves can be responsible for altitudinal neglect. 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