Suppression of spontaneous nystagmus during different visual fixation conditions

Analysis of spontaneous nystagmus is important in the evaluation of dizzy patients. The aim was to measure how different visual conditions affect the properties of nystagmus using three-dimensional video-oculography (VOG). We compared prevalence, frequency and slow phase velocity (SPV) of the spontaneous nystagmus with gaze fixation allowed, with Frenzel’s glasses, and in total darkness. Twenty-five patients (35 measurements) with the peripheral vestibular pathologies were included. The prevalence of nystagmus with the gaze fixation was 40%, and it increased significantly to 66% with Frenzel’s glasses and regular room lights on (p?<?0.01). The prevalence increased significantly to 83% when the regular room lights were switched off (p?=?0.014), and further to 100% in total darkness (p?=?0.025). The mean SPV of nystagmus with visual fixation allowed was 1.0°/s. It increased to 2.4°/s with Frenzel’s glasses and room lights on, and additionally to 3.1°/s, when the regular room lights were switched off. The mean SPV in total darkness was 6.9°/s. The difference was highly significant between all test conditions (p?<?0.01). The frequency of nystagmus was 0.7 beats/s with gaze fixation, 0.8?beats/s in both the test conditions with Frenzel’s glasses on, and 1.2?beats/s in total darkness. The frequency in total darkness was significantly higher (p?<?0.05) than with Frenzel’s glasses, and more so than with visual fixation (p?=?0.003). The VOG in total darkness is superior in detecting nystagmus, since Frenzel’s glasses allow visual suppression to happen, and this effect is reinforced with gaze fixation allowed. Strict control of visual surroundings is essential in interpreting peripheral nystagmus.     

Spontaneous and positional nystagmus in healthy persons demonstrated only by electronystagmography: physiological spontaneous nystagmus or "functional scar"?

We wanted to ascertain whether a physiological horizontal vestibular spontaneous nystagmus is existent, or whether the spontaneous and positional nystagmus seen in clinically healthy persons in the electronystagmogram -- when fixation had been excluded completely -- was always the result of earlier damages to the vestibular system (Jatho). For this purpose we tried to detect a spontaneous and positional nystagmus in 102 healthy persons from 6 age groups (17 each) between 11 and 70 years of age. When the ENG was registered with open eyes in darkness, 63 out of the 102 test persons had a horizontal spontaneous or positional nystagmus, however, under the Frenzel glasses there was a nystagmus in only 2 out of these test persons. With open eyes in darkness, the frequency and intensity was the same in all age groups. With this, we believe to have proved that a physiological horizontal vestibular nystagmus does exist. We share Kornhuber's opinion that the examination with the Frenzel glasses in a dark room, together with the head shaking test and positional test, at the present time represents the best method for differentiating between physiological and pathological spontaneous nystagmus.     

Assessment of head shaking test in neuro-otological practice

The head shaking test (HST) is an important test in neuro-otological diagnosis. In our study of 277 patients complaining of dizziness we verified this importance. The results thus obtained were compared with the results recorded in 73 normal subjects. Head shaking nystagmus was observed in 73 patients. Of these 73 cases, 42 involved central diseases and 31 cases involved peripheral diseases. Head shaking nystagmus was observed in 7 subjects of the control group. A highly significant correlation was noted between head shaking nystagmus and positional nystagmus, between head shaking nystagmus and the caloric test and between head shaking nystagmus and all the other spontaneous types of nystagmus that were investigated (eyes open in light/gaze straight ahead; eyes open behind Frenzel's glasses; eyes closed; eyes open in darkness). No correlation was found between head shaking nystagmus and cervical nystagmus and positioning nystagmus. The sensitivity of head shaking nystagmus, in comparison with other types of spontaneous nystagmus, was found to be slightly higher in cases with peripheral lesions than in those with central lesions. These data confirm the diagnostic importance of this simple test. It is also important to keep in mind that the HST has no importance for topodiagnostic purposes.     

冷热刺激先后顺序对眼震最大慢相角速度的影响

目的 :　了解变温实验检查中冷热刺激顺序同眼震反应强度的关系。方法 :应用眼震电图仪和冷热空气刺激仪进行冷热刺激检查。将 12 0例眩晕患者分成两组 ,第 1组先热后冷刺激 ,第 2组先冷后热刺激 ,观察不同冷热顺序刺激下眼震最大慢相角速度的变化。结果 :冷热反应强度差同冷热刺激顺序明显相关 ,第 2组比第1组大 (P <0 .0 1)。另外第 2组眼震最大慢相角速度半规管轻瘫差相对值和优势偏向差相对值比第 1组大 (P <0 .0 1)。结论 :变温实验中变温的顺序影响前庭对冷热刺激的敏感性和半规管轻瘫差值以及优势偏向差值。     

Spontaneous and positional nystagmus in healthy persons demonstrated only by electronystagmography: Physiological spontaneous nystagmus or “functional scar”?

Summary We wanted to ascertain whether a physiological horizontal vestibular spontaneous nystagmus is existent, or whether the spontaneous and positional nystagmus seen in clinically healthy persons in the electronystagmogram — when fixation had been excluded completely — was always the result of earlier damages to the vestibular system (Jatho). For this purpose we tried to detect a spontaneous and positional nystagmus in 102 healthy persons from 6 age groups (17 each) between 11 and 70 years of age. When the ENG was registered with open eyes in darkness, 63 out of the 102 test persons had a horizontal spontaneous or positional nystagmus, however, under the Frenzel glasses there was a nystagmus in only 2 out of these test persons. With open eyes in darkness, the frequency and intensity was the same in all age groups. With this, we believe to have proved that a physiological horizontal vestibular nystagmus does exist. We share Kornhuber's opinion that the examination with the Frenzel glasses in a dark room, together with the head shaking test and positional test, at the present time represents the best method for differentiating between physiological and pathological spontaneous nystagmus.This study is dedicated to Prof. Dr. D. Zühlke commemorating his 50th Birthday     

Near infrared stimulation of the equilibrium organ--first clinical experiences

BACKGROUND: A new method for the stimulation of the organ of equilibrium by means of a broad-scale and monochromatic near infrared emission was developed. This method should be examined within the framework of a pilot study, evaluated and its clinical possible applications examined. PATIENTS AND METHODS: Healthy probands (n = 15), patients with a radical cave of the ear (n = 5), patients with a defect of the tympanic membrane (n = 5) and spontaneous nystagmus (n = 5) were examined. In healthy probands an irritation with broad-scale as well as monochromatic near infrared (NIR) was performed and compared with a water irrigation (44 degrees, 50 ml in 30 seconds). The subjective, local feelings during the application and the appearance of giddiness according to irritation were recorded and the nystagmus was registered by means of videonystagmography. In patients with radical cave of the ear and tympanic membrane defects, a broad-scale NIR-irritation before a comparative irritation with warm air (44 degrees) was performed exclusively. RESULTS: In all healthy probands, a nystagmus reaction could be seen with broad-scale and monochromatic NIR. Compared to the hot water irritation slow phase velocity (SPV) was decreased however registrable by means of Frenzel glasses and electronystagmography during the culmination stage. In patients with radical cave (n = 4) and tympanic membrane defects (n = 3) showing paradoxical nystagmus reaction during hot air irritation, a nystagmus to the site of stimulation resulted by means of light calorisation. In patients with a spontaneous nystagmus an attenuation (n = 1) or inversion (n = 2) could be achieved by NIR-radiation. CONCLUSIONS: The method of the NIR-radiation is suitable in clinical practice for the caloric test proofing warm reaction. Vaporization cold does not occur. The application of heat charm is better proportionable and steerable than during air irritation. The procedure is sterile, noiseless and non-contact. Difficulties in interpretation of results of vestibular tests because of evaporation coldness do not occur.     

Walk-rotate-walk test identifies patients responding to Lempert’s maneuver, with benign paroxysmal positional vertigo of the horizontal canal

Two hundred and fifteen patients were diagnosed and treated for benign paroxysmal positional vertigo of the horizontal canal (BPPV-HC). All patients were tested with conventional positional nystagmus tests lying supine and rotating head for geotropic nystagmus, registered with Frenzels glasses, and in 109 cases with ENG. The walk-rotate-walk (WRW) test, developed by one of us (T.R.) and described in the text, was applied to all patients. The immediate good treatment results with Lempert’s maneuver verify the correct diagnosis of BPPV-HC. The WRW test is a more sensitive test for BPPV-HC than earlier positional tests. The unhabituated acute phase of vestibular neuritis shows positive test results and must be eliminated with caloric tests. The WRW test identifies as a dynamic test patients with symptoms of even lesser magnitude, where the compensatory capacity of the equilibrium system suppresses the diagnostic findings with earlier positional horizontal canal tests. Received: 14 December 2000 / Accepted: 5 February 2001     

前庭自旋转试验在前庭功能评定中的价值

目的：分析前庭自旋转试验（VAT）在前庭功能评定中的价值。方法：对48例前庭周围性眩晕患者行VAT和冷热试验（CT）。在VAT水平和垂直眼动增益、相位，水平非对称5项指标以及CT中，出现1项或1项以上异常指标即评定为该试验结果异常。结果：VAT异常者36例（75．0％），异常指标中的相位多于增益，非对称最少，相位和增益病理数据在各频率的分布一致。其中水平测试异常32例（66．7％），包括增益降低21例次，相位延迟24例次，非对称6例次，与前庭损伤侧别相符，且均出现在6．0～11．0Hz；垂直测试异常15例（31．2％），包括增益降低或升高7例次，相位延迟14例次。CT管麻痹和优势偏向单项或双项异常者33例（68．8％）。VAT和CT单独异常分别为11例和8例，均异常25例；完全性前庭损伤者的2项结果均异常，且VAT异常数据呈全频带性。结论：VAT作为高频、宽带的前庭功能检测技术，既能提供前庭高频区的功能信息，又可检测垂直半规管功能，弥补了CT的缺陷，减少了漏诊。     

Visual suppression test

The visual suppression test is one of the methods measuring the function of visual fixation. It is carried out by recording the caloric nystagmus by electronystagmography and comparing the maximum slow phase velocity of caloric nystagmus in the darkness and the slow phase velocity in the light with eyes opened. In 50 normal adults aged 16 to 31 years, the score of the visual suppression of the slow phase velocity of caloric nystagmus was 69.9 +/- 18.5%. Visual suppression was also studied in 125 cases with various kinds of vestibular diseases. The results showed that: 1. In cases with peripheral vestibular diseases, the visual suppression was normal (visual suppression over 50%). 2. In cases with cerebellar diseases, the visual suppression might be reduced (visual suppression 40%-10%) or abolished (visual suppression under 10%). It means that the flocculus or nodulus had been directly or indirectly impaired. 3. In brain stem lesions, the visual suppression might be reduced, abolished or the caloric nystagmus might even show augmentation in light (visual suppression negative). It means that the paramedian pontine reticular formation had been impaired. 4. In case of CP angle tumor, owing to compression to the vestibulo-cerebellum or brain stem, the visual suppression might be abnormal. 5. In case of congenital nystagmus, visual suppression varied from normal to abolished. Thus, the visual suppression test is useful in differential diagnosis of the central and peripheral vestibular diseases.     

A visual suppression test using post-rotatory nystagmus.

The visual suppression test is one method for examining the function of visual fixation and visual influence on vestibular nystagmus. In this study the visual suppression test using post-rotatory nystagmus was investigated in 65 normal subjects and 142 clinical cases with cerebellar lesions. In 65 normal subjects the mean +/- standard deviation of visual suppression of the slow phase velocity on post-rotatory nystagmus was 69 +/- 11%. As to the stimulation for visual suppression test, the post-rotatory method using rotatory stimulation is milder than caloric stimulation. This method is far simpler to analyze than the visual suppression test using pendular rotatory nystagmus and other vestibulo-ocular reflex tests. In the 142 patients with cerebellar lesions, reduced or abolished visual suppression on post-rotatory nystagmus was seen in 89 patients with radiologically confirmed disturbances in the vestibulo-cerebellum. And this method could identify the lesion side in the cerebellum. These results showed a correlation between the visual suppression test using post-rotatory nystagmus and one using caloric nystagmus in 65 normal subjects and 142 clinical cases with cerebellar lesions.     

Caloric vestibular test in the weightless phase of parabolic flight

Twenty-four caloric vestibular tests were conducted in 20 test subjects during parabolic flight, in which weightless periods of about 10 seconds were elicited. The caloric nystagmus disappeared completely in all experiments in weightlessness, whereas in the higher G-periods the speed of the nystagmus increased. With regard to the modes of response during the periods with increased G-values prior to and following the weightlessness, four different types could be distinguished. In mode I the speed of the slow nystagmus phase increased in the higher G-periods, the nystagmus showed a prolonged duration, while in weightlessness it faded out completely. A reversed nystagmus appeared when the primary caloric nystagmus had disappeared. In modes II, III and IV the direction of the nystagmus reversed during weightlessness. In modes II and III this reversed nystagmus appeared even when the primary caloric nystagmus had disappeared. In mode III the nystagmus resembled the type of mode II, with the difference that it faded away much earlier than could be expected. In mode IV the primary nystagmus lasted rather briefly, while the reversed nystagmus during weightlessness was also much shorter. The experiments produced two remarkable facts: the appearance of a nystagmus reversal, a 'secondary nystagmus', in all experiments in weightlessness, and furthermore great differences in findings between the individuals as well as between experiments in the same person. The only explanation for the inconsistency in the findings is the assumption that effects on other canals, otoliths and vestibular nuclei are continuously changing and therefore interfere with the only endproduct measured, the horizontal nystagmus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hennebert's sign in Menière's disease

The fistula sign without middle-ear lesion, also known as the Hennebert's sign, was observed in 7 (14%) subjects among 50 patients with unilateral Ménière's disease. The Hennebert's sign was obtained in 4 cases (57%) by negative pressure in the external auditory canal, by positive pressure in 2 cases and by both positive and negative pressures in 1 case. The Hennebert's sign is characterized by a few beats of horizontal nystagmus seen under Frenzel glasses. Caracteristically this nystagmus is of low frequency and amplitude. Most patients indicate simultaneous sensation of dizziness. The presence of Hennebert's sign seems to indicate in most cases the existence of an endolymphatic hydrops with contact of the saccular wall up to the internal face of the footplate (internal sacculostapedopexy). The test was also performed on the controlateral healthy ear used as a control. No Hennebert's sign was obtained on the healthy side. None of the patients showed any complication following the provocation of Hennebert's sign.     

Effects of ocular fixation on perrotatory nystagmus in damped pendular rotation test

Summary Effects of ocular fixation on pendular rotation nystagmus were investigated in 65 patients. There were 25 with peripheral vestibular or vestibulo-cochlear disorders, 17 with central vestibular disorders, five with congenital nystagmus, 16 patients over 60 years old with vertigo in whom peripheral vestibular disorders were ruled out, however, the causes were unknown.Damped pendular rotation test (DPRT) was performed both under darkness and employing mental arithmetic and under ocular fixation. These findings were related to those of caloric vestibular suppression test (VST) by Takemori and those of optokinetic pattern test (OKP), eye tracking test (ETT), and spontaneous nystagmus.Thirteen of 17 patients with central vestibular disorders and five with congenital nystagmus showed loss of visual suppression during ocular fixation in DPRT, whereas in cases of peripheral lesions, visual suppression was observed. Loss of visual suppression during ocular fixation in DPRT was often seen in cases of brainstem and cerebellar lesions. In brainstem lesions, perrotatory nystagmus was evoked during ocular fixation, whereas no nystagmus was seen in darkness with eyes open. In cerebellar lesions, perrotatory nystagmus was partly suppressed or decreased during ocular fixation. Relationships between the direction of the visual suppression during ocular fixation in DPRT and the side of the lesion were not apparent.Ocular fixation test in DPRT has a diagnostic value not only for central lesions, but for differentiating brainstem lesion from cerebellar lesion with the findings in DPRT under darkness. The findings under ocular fixation in DPRT are closely related to those of VST in cases of caloric nystagmus.     

Caloric eye-tracking pattern test: visual suppression and the possibility of simplified differential diagnosis between peripheral and central vertigo

During the examination of patients who complain of vertigo or who have equilibrium disorders, often identifying the etiology of the disorders is difficult (i.e., determining whether it is dependent on a peripheral or a central vestibular disorder). To attempt to determine the etiology in these cases, we devised a new method: the caloric eye-tracking pattern test. In normal subjects and in patients with peripheral disorders, as is well-known, caloric nystagmus has little influence on the eye-tracking pattern. In contrast, in patients with central vestibular disorders, caloric nystagmus evoked abnormalities in the eye-tracking pattern, either superimposed or as saccades, despite the fact that the eye-tracking pattern before caloric stimulation was normal. These findings result from the visual suppression mechanism to vestibular nystagmus. We can conclude that the visual suppression to vestibular nystagmus is evoked more strongly by pursuing a moving visual stimulus than by gazing at a stationary target. These results are interesting, not only from the physiological viewpoint but from the clinical viewpoint. The differential diagnosis should include both peripheral and central vertigo.     

Visual suppression test

The visual suppression test is one of the visual fixation tests. It is performed by recording caloric nystagmus by ENG, and the maximum slow phase velocity of caloric nystagmus in darkness is compared with the slow phase velocity in light with eyes open. Visual suppression of slow phase velocity of caloric nystagmus is 54 +/- 12% in 52 normal adults ageing from 21 to 40. Visual suppression in normal subjects is not influenced by water temperature used for the caloric test and not changed by background illumination in light. Visual suppression is stronger when the target is closer to the eyes of the subjects. The following abnormalities have been diagnosed by this test: flocculus and nodulus lesions on the side of the lesion; inferior olive lesions; parietal lobe lesions; compensation after unilateral sudden loss of inner ear function.     

Isolated directional preponderance of caloric nystagmus: II. A neural network model

HYPOTHESIS: The purpose of this study was to simulate an isolated directional preponderance (DP) on bithermal caloric testing by constructing a realistic neural network model. The simulation was designed to capture not only the characteristics of the nystagmus response to caloric stimulation but also the response to rotational stimulation in patients with an isolated caloric DP. BACKGROUND: The nature of an isolated DP--that is, a DP in the absence of a significant spontaneous nystagmus or canal paresis--is outlined in the preceding article. In this article, the authors investigate the possible neural basis for an isolated caloric DP using the mathematic modeling technique of neural network simulation. Neural network models are typically abstract in nature; however, in this case the network was based on the known structure and function of the central vestibular system. METHODS: The neural network model was based on the known neuroanatomy and neurophysiology of the horizontal vestibuloocular reflex pathway. A leftward-rightward asymmetric modification of the dynamic responses of simulated medial vestibular nucleus type IA neurons on one side, or of type 2 neurons on the other side, to peripheral input would generate an isolated caloric DP. RESULTS: The values of DP and associated canal paresis produced by the network were within the same range as in the patient group. The network also predicted that the rotational DP would be lower than the caloric DP: between 2.5% and 56.9% of the caloric DP value. The actual rotational DP value was between 3% and 57% (average 41%) of the corresponding caloric DP value. CONCLUSIONS: An isolated caloric DP can be simulated by a neural network model by modifying the activity of model units that represent medial vestibular nucleus neurons. An asymmetric dynamic response by a gain-enhancement function of either type 1A neurons on one side or of type 2 neurons on the other was sufficient to produce an isolated caloric DP. Excitatory gain enhancement of type 2 neurons produced a smaller rotational DP than a similar modification of type 1 neurons. This result indicates a potential neural locus for the generation of an isolated DP in patients with vestibular disorders.     

Visual suppression test*

The visual suppression test is one of the visual fixation tests. It is performed by recording caloric nystagmus by ENG, and the maximum slow phase velocity of caloric nystagmus in darkness is compared with the slow phase velocity in light with eyes open. Visual suppression of slow phase velocity of caloric nystagmus is 54 ± 12% in 52 normal adults ageing from 21 to 40. Visual suppression in normal subjects is not influenced by water temperature used for the caloric test and not changed by background illumination in light. Visual suppression is stronger when the target is closer to the eyes of the subjects. The following abnormalities have been diagnosed by this test: flocculus and nodulus lesions on the side of the lesion; inferior olive lesions; parietal lobe lesions; compensation after unilateral sudden loss of inner ear function.     

Nystagmus and vibration test research of mechanisms, theoretical methods: on 52 cases of unilateral vestibular lesions

OBJECTIVE: The aim of the present study was to examine the characteristics of the Vibratory Nystagmus (VN) optimise the topography and the frequency of the stimulus, determine the origin of the VN and analyse its clinical implications. MATERIAL AND METHOD: 52 severe unilateral vestibular lesions (SUVL) (post-surgical vestibular areflexy) were studied. The vibratory nystagmus was measured by 2D and 3D videonystagmography (Synapsis, France). The stimulus was applied with a 3S vibrator at the vertex, both masto?ds, and posterior cervical muscles at frequencies ranging from 20 to 150 Hz. For topographic optimisation, stimulation was given with S vibrator (Synapsis, France) at 100 Hz. The interferences between the vibratory test (VT) and the caloric test (CT) were studied on the normal ear (in 11 subjects). The same study was carried with the optokinetic test. RESULTS: The VT revealed a defective nystagmus at all frequencies of stimulation. Optimal response was obtained in a band frequency of 80-120 Hz. Stimulations at 100 Hz showed optimal responses for masto?d topography (responses in 96% of the cases). Stimulation at the posterior cervical muscles and at the vertex indicated respectively a response in 90% and 60% of the cases. The efficiency of the masto?d stimulation is not correlated with the side of stimulation (p = 0.9). The interference between the VT and caloric test (CT) at cold water (30 degrees et 20 degrees C) exhibited the inversion of the caloric nystagmus during the vibrator stimulation. The resulting nystagmus is respectively an algebric subtraction or addition between the pre-existing caloric nystagmus and the value of the vibratory nystagmus obtained before caloric test. Adaptation of the VN is moderate. The interference between the VT and the optokinetic test resulted in a subtraction or addition effect, according to the side of the lesion and the direction of the optokinetic stimulus. CONCLUSION: The VT is an efficient stimulation in masto?d topography. The vestibular contribution is bilateral by bony conduction of the vibration, it explores frequencies ranging from 30 to 120 Hz, with a maximum of response at 100 Hz. The VT interacts with the caloric test and the optokinetic test. The stimulation is very strong, and is able to inverse the caloric nystagmus at cold water stimulation (20 degrees C). In labyrinthine-defective subjects, the VN is always defective at all frequencies, whatever is the topographic location of the stimulus, and the position of the head.     

Monocular electronystagmographic analysis of caloric nystagmus

We compared the horizontal component of nystagmus of the right and left eyes using monocular recording of electronystagmography. We examined the eye movements of 135 patients during bithermal caloric testing and those of 50 patients during the rotation test. We measured the number of nystagmic beats, the slow-phase velocities, and the amplitudes during 10 seconds of the culmination phase of caloric response. We also measured the number of nystagmic beats during the first 30 seconds in postrotatory nystagmus. The eye on the cold-irrigated side moved significantly more strongly than did the eye on the nonirrigated side, whereas a warm irrigation did not induce a significant difference between the irrigated and nonirrigated eyes. The summated activities of each eye during the four different stimulations under bithermal caloric testing did not show any significant differences. The activities of postrotatory nystagmus were almost equal in both eyes in 50 patients. We concluded that the inhibitory effect of cold caloric stimulation is probably transmitted more intensively to the eye on the irrigated side.     

头晕眩晕与眼震强度的关系研究

目的 通过冷热试验诱发头晕和/或眩晕时的眼震强度,探讨头晕眩晕与眼震强度的关系。 方法 对399例前庭周围性疾病患者进行常规冷热试验检查,以双耳冷热气刺激诱发出头晕和/或眩晕感时的眼震强度为指标,比较分析头晕及眩晕感与眼震强度的关系。 结果 冷热刺激诱发头晕眩晕及关联眼震总体分析,出现眩晕时的眼震强度总是大于头晕。左右耳冷热气刺激诱发头晕、眩晕的眼震阈值分别为:左耳冷4.2°/s、5.9°/s,左耳热4.2°/s、8°/s,右耳冷4.6°/s、6.2°/s,右耳热5.3°/s、 6.5°/s。399例患者进行双耳冷热交替刺激,共计1 596次试验,诱发出头晕513次(32.14%),其中312次仅有头晕、201次在头晕后10 s左右还出现眩晕;诱发出眩晕906次(56.77%),其中705次直接出现眩晕,无从头晕向眩晕进行过渡,另201次眩晕出现在头晕10 s左右之后;未引出头晕眩晕378次(23.68%)。 结论 眩晕对应的眼震强度阈高于头晕,眼震较弱时患者表现为头晕,较强时则呈现眩晕。冷热气刺激诱发眼震强度由弱到强及同时存在的由头晕到眩晕现象,提示头晕眩晕症状与两侧前庭张力差的大小相关。