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Dr.Chanchal Gadodiya, Dr.Anwesha Manna

ABSTRACT-

Synopsis:-

It is comparative observational study carried at tertiary care centre, 50 patients in age group of 8 to 60 years with abnormal head posture due to ocular conditions were included in the study with their informed consent. Each patient underwent head posture measurement in seating position with wall at back and reading from Snellens chart at 6m, using android apps Eye tilt (See Vision ,LLC) and Protractor (keuwsoft). Both applications are camera based, for measuring head tilt Eye tilt app was used , horizontal line was aligned with both eyes passing through pupil while vertical line was aligned with nose, it gives real time reading in degrees. For measuring  face turn and chin depression or elevation Protractor app was used.

Face turns i.e. rotation along longitudinal axis was estimated by  standing above the patients head and placing phone parallel to the floor, care was taken that nose could be visualized  in image, plumb lines i.e. green and purple line were aligned along 180 degree and 90 degree marking on protractor ,now one marker line was aligned along purple line while other marker line was aligned along the naso occipital line,  angle between these two marker lines gave face turn. Chin elevation and depression was measured by standing on side of face, green plumb line was aligned horizontally along 0-180 marking of protractor while purple line was aligned with 90 degree marking, now one of the marker line was aligned with green plub line while other marker line was aligned along orbitomeatal line, angle between two noted. Repeat reading was obtained after correcting head posture. Difference between two reading   gave us angle of chin elevation / depression. Each patient underwent head posture measurement twice once with android apps and once with CROM by two different examiners who were blinded to each others measurements.  All patients were examined by same examiners. Data collected by two methods was statistically analysed. Angles obtained with android applications were compared with angles obtained from CROM Device.

RESULTS

Analysis showed that measurements obtained by two methods were comparable. The mean variation obtainedwas 1.7 degrees for face turn, 1.5 degree for head tilt, 1.25 degree for chin elevation, It is  small from clinical and surgical point of view. Thus we conclude that this method of AHP measurement was successful by following simple instruction and can be used in day to day clinical practice by ophthalmologist.

KEYWORDS                                                                                                                                             Anomalous head posture, smartphone, CROM

INTRODUCTION-

Anomalous Head posture is not uncommon finding in Paediatric ophthalmology and strabismology practice and it may be primary reason for optical or surgical intervention. There are multiple aetiologies like neurologic, orthopaedic or ophthalmologic causing AHP.(1,2)Ophthalmologic are, some forms of strabismus, nerve palsies, nystagmus, ptosis, visual field defects and refractive errors(astigmatism).

Ophthalmic origin AHP serves as motor compensatory mechanism to improve vision (quality and quantity) or to avoid diplopia and maintain binocularity. (3)Detail evaluation and understanding the basic mechanism behind AHP will help in diagnosis of underlying pathology and planning management. It can be present since childhood like in patients with congenital ptosis, nystagmus, DRS or recently acquired like in nerve palsies. It can be constant, alternating(PAN) or present only when patient is engaged in visually demanding tasks(nystagmus). Ocular ‘‘torticollis’’  or AHP can be simple (head tilt, face turn, or chin up or down), or it can be combined.

Incomitant strabismus like 6th, 4rth nerve palsies , DRS, browns syndrome, TRO, orbital fracture are the most common cause of ocular AHP accounting for 63–70 % of ocular torticollis. For this the patient is assuming the head position to obtain alignment, fusion, and avoid diplopia(4,5,6)Nystagmus is the second common cause for ocular torticollis accounted for 17–20 % in different series . The patient acquires AHP to keep eyes in null zone while fixing where nystagmus is minimal.(7,8)In casesof early-onset homonymous hemianopia in children,torticollis, which is ipsilateral to the visual field defect,was observed. In cases of central visual field defect inchildren with fixation loss, elevation of the mentum hasbeen reported(1,2).Refractive error-related AHP appears because ofattempts to obtain the best visual acuity. Khawam et al.(9)observed astigmatism of 1-4D in most patients with refractive error-related AHP. High myopic individuals may lower the mentum or tilt the head in an attempt to createa pinhole effect with the nose or forehead.

Accurate measurement and documentation of AHP is important when intervention is planned. Multiple methods have been explained to measure AHP like CROM, Goniometer, photographic method. Aim of this study is to report a method of AHP measurement using smart phone applications and compare it with existing standard method of AHP measurementi.e. CROM device.

METHODS

It is comparative observational study carried at tertiary care centre, 50 patients in age group of 8 to 60 years with abnormal head posture due to ocular conditions were included in the study with their informed consent. Each patient underwent head posture measurement twice one with CROM and once with smart phone apps,in seating position with back support. Android apps Eye tilt (See Vision ,LLC) and Protractor (keuwsoft) are camera as well level based. For measuring head tilt Eye tilt app was used , horizontal line was aligned with both eyes passing through pupil while vertical line was aligned with nose, it gives real time reading in degrees.

For measuring face turn and chin depression or elevation Protractor app was used. Face turns i.e. rotation along longitudinal axis was estimated by standing and placing phone above the patients head parallel to the floor, care was taken that nose could be visualized in image, after aligning centre point of protractor with reference point ( bregma)plumb lines i.e. green and purple line were aligned along 180 degree and 90 degree marking on protractor ,now one marker line was aligned along purple line while other marker line was aligned along the naso occipital line,  angle between these two marker lines gave face turn. Chin elevation and depression was measured by standing on side of face,after aligning centre of protractor with reference point ( auditory meatus), green plumb line was aligned horizontally along 0-180 marking of protractor while purple line was aligned with 90 degree marking, now one of the marker line was aligned with green plumb line while other marker line was aligned along orbitomeatal line, angle between two noted. Repeat reading was obtained after correcting head posture. Difference between two reading   gave us angle of chin elevation / depression. Measurements with these two methods were taken by different examiners who were blinded to each others measurements.  All patients were examined by same examiners. Data collected by two methods was statistically analysed. Angles obtained with android applications were compared with angles obtained from CROM Device.

RESULTS

Out of 50 patients in age group of 8 to 60 yrs presenting with AHP, 70 % had some form of Incomitant strabismus, 24% had nystagmus, 6% had ptosis as shown in table 1.

Table 2 shows the types of AHP and mean variation in measurements between  measurements obtained from CROM and android apps.              We had 20 patients with isolated face turns,mean variation from CROM device for them was 1.7˚ with range from 5 to 2 degree. 12 patients had isolated head tilt, mean variation of measurement with android app from CROM device for isolated head tilt  was  1.5˚ with range from 3to 1 degree .For isolated chin up patients which were 8 in number it was 1.25 ˚ with range from 3 to 2 degree. We had only one patient with isolated chin depression for whom measurement with both methods was equal. As we can see very reliable and comparable AHP measurements have been obtained in case of isolated AHP from android app when placed against CROM device which is considered as gold standard for AHP measurement.

In cases where combination of AHP are present, mean variation for Face turn was 6.6˚, for head tilt was 1.6˚, for chin depression was 5˚.  As we can see except head tilt there was increase in variation from measurements obtained by using CROM.

Paired t-test/ Wilcoxon sign rank test was used to find out the significant difference in abnormal head posture between CROM and APP. P-value less than 0.05 considered as statistically significant. Table no 3 shows p-value (>0.05) indicating that there is no significant difference in AHPmeasurement  between CROM and APP.

DISCUSSION

Multiple methods and tools have been used to measure AHP inpast . With the advances in applications of smartphone, expensive tools are being replaced in clinical routine of doctors. But clinical studies are lacking on reliability of these applications for measuring AHP. Here we have used Android apps Eye tilt (See Vision ,LLC) and Protractor (keuwsoft) which are freely available on google play store for measuring AHP in 50 patients of varying  aetiologies and compared readings with that obtained by using CROM device.

Most important step in measuring AHP with these applications is proper positioning of smartphone which is guided by level sensitivity (plumb line) of apps to avoid vertical and horizontal tilting while measuring chin elevation/depression and face turn respectively. Second important step is alignment of reference point on skull and face to centre of protractor in case of protractor and cross in case of eye tilt app. As observed in results with correct method, measurements obtained with these apps in isolated head posture were comparable with CROM measurements, variation was 1-2 degree which in not significant clinically or surgically.While in patients with combination of head posture except head tilt other head posture had variation of 5-7 degrees from that obtained with CROM.

Variation in these measures might be due to failure to correctly align reference point and plumb lines. Specially in cases with chin depression, it was difficult to visualize nose from above.This  indicates the need to have a standardized reference point in order to make this method more precise. Adding artificial reference points that are either physical (lines or points onthe patient’s head) or digital could increase accuracy but would increase the complexity of the method. Advantage of smartphone method over CROM is no special instrument required, less tedious, cheap, easy, patient does not need to wear any head band like in CROM . But anatomical variations in reference point may alter measurements in this method.

CROM(cervical range of motion) device was developedby the orthopedists Garret, Youda, and Madson in 1993 to measure the range of motion ofcervical spine.CROM gold standard device composed of three inclinometers placed at three different positions: one near the left ear for flexion/extension (sagittal plan) and another for the lateral flexions on the forehead (frontal plane).Both are gravity dependent. The last positioning was the top of the head. For this one, the magnetic dependence was compensated by placing an adapted brace. In 2000, Kushner(10) used this device to evaluate the field of binocular vision at a fixed distance, quantify the magnitude of AHPs, and assess ductionlimitation.This approach has a high cost and low availability. There is currently no method that is practical, precise, and simple for measuring AHP in routine ophthalmologic examination.

Simplest and basic method of AHP assessment used in clinical practice is by using goniometer. The following methods are typical by the using of some tools or technology. In Young, J.D., 1988 (11) the main principal of this approach is based on using three mirrors and special patient ́s head markers (bands). The resulting images aretaken with the camera. After this a set of lines is drawn with respect to the reference points and adjacent knownvertical or horizontal line. The last step is measurement of the relevant angles with a protractor. Head tilt(inclination), head turn (rotation) and chin elevation or depression (flexion/extension) is evaluated. Onedrawback is the wide variation in cranial configuration found between patients and associated with age.

In Murphy, K.E. et al, 1991 (12) the main aim of this paper was to describe a system for measuring and recording cranial posture in a dynamic manner.Measurement of the declination and inclination was performed by inclinometers attached to the spectaclerims. Inclinometer is an instrument for measuring angles of tilt, elevation or inclination of an object with respect to gravity based on the accelerometers. Processing of the inclinometer voltages was performed by the adaptive data logger. The inclinometer was calibrated with a 30o plastic visor and a perpendicular spirit level.

In Ferrario, V.F. et al, 1994 (13) an integrated methodbased on the photographic technique, radiographic technique,cephalometric measurements and photographic measurements was desribed. The subjects were photographed and X-rayed in the same room. The set of standardized landmarks was traced on all the records. On all photographs, the soft tissue FandworkNasion and the soft tissue Pogonion were traced, and the angle between the above mentioned soft tissue marks and true vertical was calculated. The same angle was calculated on the cephalometric films, and the difference between the two measurements was used to compute the position of the soft and hard tissues. These new values were compared with the values previously observed in the standard cephalometric orientation. The main drawback is exposition of patients to X-ray and relatively time consuming procedures.

In Ferrario, V.F. et al, 1995 (14) the new methodbased on the television technology was developed as method faster than conventional photographic analysis.The subject’s body and face were identified by the 12points. All subjects were pictured using a standardized technique for frontal views of the total body and lateralviews of the neck and face. After 20 seconds ofstandings, two 2-second films were taken for eachsubject. Based on the image analysis program thespecified angles were calculated after the digitization of the recorded films.

Hald et al.(15) have shown that the patient’s head position could be accurately assessed using a motion sensor-based system (InterSense, Inc., Billerica, MA). The need for proper fixation of the sensor to the patient’s head and its high cost are limitations for its use.

Kim et al.(16) developed an infrared optical head motion sensor using two Nintendo Wii® controls (WiiMote;Nintendo Co., Ltd., Kyoto, Japan). This system showed strong agreement with CROM, had good reliability in the comparison between tests, and was less expensive than the system by Hald. Nevertheless, patients were required to wear the device on their heads, and the examiners needed to set a 3D-virtual space before taking measurements.

Oh et al.(17) developed a digital system for measuring head position by incorporating Microsoft Kinect®, and they found agreement with measurements taken with the help of the CROM device. This approach does not rely on the use of any apparatus on the patient’s head and requires good understanding of Microsoft Kinect®.However, the distance between the patient and the Microsoft Kinect Head Tracker® can influence head position measurements.

CONCLUSION

The present study has some limitations like more variation in AHP in presence of combination of AHP and effect of facial configuration on measurement, asymmetry of the reference points used in the study may be a confounding factor in head position measurements, indicating the need for a fixed reference point for evaluating AHP with better precision. Though some limitations are present but based on the findings of the present study,  our method used for measuring AHP is reliable and comparable to gold standard CROM device and has a mean variation of 1.7 degrees for face turn, 1.5 degree for head tilt, 1.25 degree for chin elevation AHPs. The variations obtained in AHP measurements were small from clinical and surgical point of view. Thus we conclude that this method of AHP measurement was successful by following simple instruction and can be used in day to day clinical practice by ophthalmologist.

Tables and Images

Diagnosis No of patients Percentage
LR palsy 10 20%
SO palsy 11 22%
DRS 5 10%
Browns syndrome 3 6%
MED 3 6%
CFEOM 1 2%
V pattern esotropia 1 2%
Nystagmus 12 24%
Ptosis 3 6%
Plagiocephaly 1 2%

Table 1- Aetiology of AHP

Type of AHP Percentage Mean variation in measurement from CROPM
Face turn 40% 1.7˚ (5˚- 2˚)
Head tilt 24% 1.5˚ (3˚- 1˚)
Chin elevation 16% 1.25˚ ( 3˚-2˚)
Chin depression 2% –
Combination 18%
                  Face turn 6.6 ˚(10˚- 5˚)
                  Head tilt 1.6˚ (3˚-1˚)
                  Chin elevation –
                  Chin depression 5 ˚(3˚ -10˚)

 

Table 2- Type of AHP with their mean variation between measurement obtained using android app and CROM 

AHP CROM

Mean (SD)

 APP

Mean (SD)

 Mean difference

(95% CI)

 P-value
Face turn 19.50(8.09) 19.50(6.6) 0(-1.19 to 1.19) >0.999
Head tilt 16.25(3.77) 16.58(3.60) -0.33(-1.49 to 0.83) 0.540
Chin elevation 18.89(4.86) 18.44(4.67) 0.44(-0.89 to 1.78) 0.466
Face turn,

Chin elevation

 20.00

13.33(2.89)

 10.00

8.33(2.89)

 10(10 to 10)

5(5 to 5)

 0.083

0.083
Face turn,

Head tilt

 15.00(3.54)

12.00(2.74)

 11.25(6.29)

11.20(2.77)

 3.75(-11.31 to 18.81)

0.80(-0.56 to 2.16)

 0.486

0.178
Face turn,

Head tilt,

Chin elevation

 20

10

20

 15

10

20

 – –

Table 3- CROM vs. APP

Paired t-test/ Wilcoxon sign rank test was used to find out the significant difference in abnormal head posture between CROM and APP. P-value less than 0.05 considered as statistically significant. In the above table, p-value (>0.05) shows that there is no significant difference in AHP between CROM and APP.

References

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