Effect of forward head posture on sensorimotor integration

there will be no intervention Procedures: 1-Assessment of forward head posture: The base of the camera was set at the height of the subjects’ shoulder. The tragus of the ear was marked, and a plastic pointer was taped to the skin overlying the spinous process of the C7 vertebra. We measured the craniovertebral angle, which is defined as the angle between a horizontal line passing through C7 and a line extending from the tragus of the ear to C7. (Mi-Young Lee et.al, 2014). The subject is seated and we take a lateral view picture. (Sjan-Mari van Niekerk et.al, 2008). 2-somatosensory evoked potential (SSEPs): Position of the patient: Because the very small size of the cortical potentials, frontal, spinal,and erbs point very good relaxation of the subject is vital Therefore ,the subject was lay supine on a softly padded table with pillows under the head and knees. Skin preparation under the stimulating electrode: Skin overlying the dermatome, was carefully washed using methylated alcohol, and then dried by rubbing the skin with dry clean cotton wool. This procedure was repeated until the skin become red aiming to reduce skin resistance .Great care was taken not to break or abrade the skin under the stimulating electrode, as they may the stimulus painful. Skin preparation under the recording electrode: Careful attention was paid to cleaning and scarifying the skin before the attachment of the recording electrodes in the scalp. The hair was separated and the skin in between was thoroughly cleaned by methylated alcohol and sand paper was used to gently abrade the skin sites by removing several superficial layers of the skin and skin oils. It is generally accepted that abrasion is considered sufficient when the impedance measured across two such electrode preparation sites is between 1,000 and 5,000O. When the impedance is less than 1000 ohm, care must be taken to avoid a situation in which amplifier is short –circuited through aberrant conduction pathway such as excess perspiration or electrolyte paste between two electrodes. As in this instance, the impedance through the abnormal conducting pathway is less than through the electrodes and the biological signal would rather the path of least impedance, thereby by passing the instrument (Dumitru, 1995). Stimulation procedure Stimuli consisted of electrical square pulses, 1ms in duration delivered at rates of 2.47Hz and 4.98Hz through Ag/AgCl ECG conductive adhesive electrodes (’MEDITRACE’ 130 by Ludlow Technical Products Canada Ltd., Mansfield, MA) (impedance <5 kO) placed over the median nerve and ulnar nerve separately and both nerve at the same time at the wrist of the right hand, with anode proximal. SEPs were recorded at the two rates since the slow rate 2.47Hz does not lead to SEP peak attenuation and the fast rate 4.98Hz attenuates the N30 SEP peak resulting in the N24 SEP peak being accurately measurable . The stimulus intensity was increased until motor threshold was achieved for each individual participant. Motor threshold was defined as the lowest stimulation intensity that evoked a visible muscle contraction of the abductor pollicisbrevis muscle theses procedures will be done for median nerve and ulnar nerve and both of them. SEP recording parameters SEP recording electrodes (1.8288m Traditional Lead, 10mm disc, 2mm hole gold cup EEG electrodes, Grass Technologies, An Astro-Med, Inc. Subsidiary, Rockland, MA) (impedance <5 kO) were placed according to the International Federation of Clinical Neurophysiologists (IFCN) recommendations. Recording electrodes were placed on the ipsilateral Erb’s point, over C5 spinous process (Cv5), the anterior neck (tracheal cartilage), 2cm posterior to contralateral central C3/4, which will be referred to as Cc’, and a frontal cite (6cm anterior and 2cm contralateral to Cz), which will be referred to as the Rossi site .. The C5 spinous process was referenced to the trachea while all other electrodes were referenced to the ipsilateral earlobe. A 1.8288m Traditional Lead, 10mm disc, 2mm hole gold cup EEG electrode was also used as a ground, placed in the mouth of participants. All stimulating and recording procedure will be performed before and after the motor typing task for 20 minutes for both Group A and Group B . Typing task involves typing out a paragraph of a text as quickly and accurately as possible for 20 minutes. 'We will compare between the amplitude and latency of somatosensory evoked potential on subjects with forward head and normal subject before and after performing typing task'