Coll. Antropol. 31 (2007) 3: 823–827 Original scientific paper Impairment of Proprioception After Whiplash Injury Melita Uremovi}1, Selma Cvijeti}2, Marija Bo{njak Pa{i}3, Vesna [eri}3, Branka Vidrih4 and Vida Demarin3 1 Zagreb Insurance Company, Zagreb, Croatia 2 Institute for Medical Research and Occupational Health, Zagreb, Croatia 3 Department of Neurology, University Hospital »Sestre milosrdnice«, Zagreb, Croatia 4 Department of Psychiatry, University Hospital »Sestre milosrdnice«, Zagreb, Croatia A B S T R A C T Whiplash injury usually occurs in traffic accidents. Persons experienced this injury might have an impairment of proprioception clinically expressed as inability to determine the exact position of their heads. The aim of this study was to examine the loss of proprioception in people who had a whiplash injury. The study included 60 subjects with cervical spine injury, aged 20 to 50 years and 60 healthy volunteers matched by sex and age. The instrument used for cervical spine mobility assessment was the Cervical Measurement System (CMS), which determines the ability of subjects to re- turn their head in the exact position as it was before they turned it 30 degrees left or right. Patients with cervical spine in- jury showed significant impairment of proprioception in comparison with healthy subjects (P<0.001). The results support the hypothesis that subject with recent cervical spine injury have incorrect perception of their head position. Therefore, their rehabilitation should include the correction of proprioception and head coordination. Key words: whiplash injury, proprioception, standard measurements of cervical spine mobility (CMS), rehabilita- tion of cervical spine injury Introduction Cervical spine is frequently exposed to injury due to great mobility and head mass which is approximately 4.5 kg1. Cervical spine injuries often result from car acci- dents (3) and are usually complex in origin2. The distance between the driver’s or passenger’s head and the head restraint is between five and 25 cm. In a car accident, the head and the neck are abruptly thrust backwards, which can result in spinal injury3. Initial symptoms such as neck pain, headache and vertigo, are of low intensity. Later symptoms include pain spreading through the arms, vision disturbance and limited mobility of cervical spi- ne4–8. Symptoms can last for months, even for years after the injury. The duration of rehabilitation depends on the patient’s age, severity of injury and type of medical treatment9. The initial treatment includes neck immobi- lization, analgesy and physical therapy10,11. Standard re- habilitation includes cervical spine mobility and cervical muscle exercises12. Cervical spine injuries can result in the damage of sense receptors which surround and innervate cervical structures. These sensors are muscle spindles, situated in inter-vertebral and dorsal muscles, which transmit in- formation about changes in muscle length to the central nervous system (CNS)13,14. There is evidence of inhibi- tion of gamma motor neurons, due to the pain after in- jury, which results in incorrect information from muscle spindles to the CNS and in incorrect proprioceptive sen- se15. This is important in everyday activities, because moving to any object requires precise sense of the head and neck position16. Most published articles on whiplash injury have ad- dressed its pathogenesis, mechanism and epidemiology. On the other side, only a few authors have investigated the damage of proprioceptive sense as a frequent cause of imbalance in patients with pull injuries17,18. 823 Received for publication October 4, 2005 The aims of this study were: 1. to determine the damage of proprioception in patients who had a whiplash injury. Proprioception is here de- fined as ability to repeatedly return the head in the ex- act position as it was before turning the neck 30 de- grees left or right. 2. to show that Cervical Measurement System (CMS), which is used to determine head movement to a defined posi- tion, is a reliable method for this purpose. Subjects and Methods The study included 60 subjects of both sexes (30 women and 30 men), aged 20 to 50 years, who were treated for whiplash injury at the Physical Medicine Unit and Neurology Unit of Clinical Hospital »Sestre Milosrd- nice« in 2002. All patients experienced the whiplash in- jury in a traffic accident. They were examined by surgeon after injury (mean time after injury: 16.7 hours; range: 1–48 hours). Whiplash injury was diagnosed to all pa- tients after clinical and x-ray examination, according to the criteria which are used in every-day clinical practice: radiologically cervical hyper- or hypolordosis, or even no radiological signs with limited neck mobility and spasm of paravertebral muscles. Classification was performed also by the surgeon, according to QTF protocol, which classifies patients into four grades according to their clin- ical symptoms and associated syndromes: Grade 0 – no pathological or clinical signs of injury; Grade 1 – Patho- logical signs: microscopic or multiple small lesions of soft tissue. Clinical signs: no muscular spasm; Grade 2 – Pathological signs: bleeding in soft tissue, including liga- ments, tends and joint capsule. Clinical signs: neck stiff- ness, PVM (paravertebral muscles) spasm, Grade 3 – Pathological signs: grade 2 + neurological damages as a primary consequence of injury or secondary due to bleed- ing or inflammation. Clinical signs: neck stiffness + neu- rological signs, Grade 4 – serious neck injury with radio- logical signs of cervical spine instability or fracture19. Patients who were classified to be in the second or third degree of QTF Protocol were included in this investiga- tion. The injuries were treated equally in all patients: resting and neck immobilization in mean duration of 10 days and analgesia. Functional X-rays of cervical spine were performed at the end of immobilization. Physical therapy lasted 15 days in average and consisted of strengthening neck muscles and application of low-en- ergy, high-frequency pulsed electromagnetic therapy on pain sites. The control group consisted of 60 subjects (30 women and 30 men), matched by sex and age, who were treated in the same hospital units in 2002, but never experienced a whiplash injury and had no abnormality found by cervi- cal X-ray. All subjects were taken medical history. Detailed data were collected about the accident, crash sites and pa- tients’ seat in the car. Measurement of head motion to the defined position was performed three months after physical therapy us- ing a CMS. It is a plastic device, which is positioned on the patient’s head. Head movements in the frontal and sagital planes were measured with gravitation goniome- ter, while compass goniometer was used for movements in the transversal plane. Coefficient of variation for CMS was obtained by ten measurements of head movement in one healthy volunteer. The coefficient was 1.36%. A va- lidity, and sensitivity of CMS in measuring neck motility has already been proved in several studies20,21. During the measurement, subjects were seated in a chair, with the head in the neutral position (0° of rota- tion). They fixed their eyes on a point on the wall, which was in the level of their eyes. The CMS was placed on the patient’s head. At the beginning of the examination, the patients closed their eyes and let the investigator rotate their head for 30° to the right and then return it to the neutral position (0°). After that, the patient was asked to repeat the movements three times in 60 seconds. The whole procedure was repeated for the left turn. The CMS served to determine whether the head returned to the neutral position (0°). Statistical analysis was performed using Statistica for Windows version 5. Data were presented as mean
stan- dard deviation. Comparison between measurements was performed by Mann-Whitney U-test. The P value of less than 0.05 was considered statistically significant. Results Most patients were injured in a rear-end collision, and then in head-on and sideswipe collisions (Table 1). There were no differences between the sexes by the type of colli- sion. Most men were drivers, while most women were front and back-seat passengers (Table 2). CMS measurements of the head movement back to the neutral position after a 30° rotation to the right and M. Uremovi} et al.: Loss of Proprioception After Whiplash Injury, Coll. Antropol. 31 (2007) 3: 823–827 824 TABLE 2 POSITION OF PATIENTS IN THE CAR DURING THE ACCIDENT Position of patient Men (N = 30) Women (N = 30) Driver 19 (63.3 %) 10 (33.3 %) Front-seat passenger 5 (16.7 %) 11 (36.7 %) Back-seat passenger 6 (20.0 %) 9 (30.0 %) Total 30 (100.0 %) 30 (100.0 %) TABLE 1 NUMBER OF SUBJECTS ACCORDING TO COLLISION TYPE Type of collision Men (N = 30) Women (N = 30) Front 5 (16.7 %) 9 (30.0 %) Rear 22 (73.3 %) 17 (46.7 %) Side 3 (10.0 %) 4 (13.3 %) Total 30 (100.0 %) 30 (100.0 %) left, showed that n the second attempt, women rotated their heads in significantly lower degree, comparing to men (p<0.05) (Table 3a and b). In the first attempt, 17 female and 22 male patients correctly turned their heads 30 degrees to the right. In the second attempt, only one female and no male patient were able to repeat the move- ment with the same precision, and in the third attempt none was able to do the same. In all attempts, there were no significant differences between men and women in turning their heads 30°. Turning their heads 30 degrees to the left, 23 female and 23 male patients did it correctly in the first attempt, five women and one man in the sec- ond attempt, and one woman and three men in the third attempt. Patients rotated their heads in significantly lower de- gree than controls (P<0.05 in the first attempt; P< 0.0001 in the second and third attempt) (Table 4a and b). No patient was able to turn her or his head for 30° in the third attempt. Patient with neck injury were not able to return the head to the neutral position of 0° after 30° rotation, un- like 93.3% controls who were able to do it (Figure 1). M. Uremovi} et al.: Loss of Proprioception After Whiplash Injury, Coll. Antropol. 31 (2007) 3: 823–827 825 TABLE 3A CMS MEASUREMENT OF HEAD ROTATION TO THE RIGHT IN THREE ATTEMPTS Men (N=30) Median Women (N=30) Median Mann-Whitney U-test First attempt 30° (28°–30°) 30° (27°–30°) n. s. Second attempt 28° (26°–29°) 28° (26°–30°) n. s. Third attempt 27° (25°–28°) 27° (26°–29°) n. s. CMS – standard measurements of cervical spine mobility TABLE 3B CMS MEASUREMENT OF HEAD ROTATION TO THE LEFT IN THREE ATTEMPTS Men (N=30) Median Women (N=30) Median Mann-Whitney U-test First attempt 30° (28°–30°) 30° (28°–30°) n. s. Second attempt 28° (26°–30°) 29° (27°–30°) p<0.05 Third attempt 27° (26°–29°) 27° (25°–29°) n. s. CMS – standard measurements of cervical spine mobility TABLE 4A CMS MEASUREMENT OF HEAD ROTATION TO THE RIGHT IN THREE ATTEMPTS IN PATIENTS AND CONTROLS Patients (N=60) Median Controls (N=60) Median Mann-Whitney U-test First attempt 29° (27°–30°) 30° (29°–30°) P<0.05 Second attempt 28° (26°–30°) 30° (29°–30°) P<0.0001 Third attempt 27° (25°–29°) 30° (29°–30°) P<0.0001 CMS – standard measurements of cervical spine mobility TABLE 4B CMS MEASUREMENT OF HEAD ROTATION TO THE LEFT IN THREE ATTEMPTS IN PATIENTS AND CONTROLS Patients (N=60) Median Controls (N=60) Median Mann-Whitney U-test First attempt 29° (27°–30°) 30° (29°–30°) P<0.05 Second attempt 28° (26°–30°) 30° (29°–31°) P<0.0001 Third attempt 27° (25°–29°) 30° (29°–31°) P<0.0001 CMS – standard measurements of cervical spine mobility Discussion This investigation shows that a CMS system for mea- suring cervical spine mobility can reliably assess the loss of proprioception in patients with cervical spine injury. There have been several studies on the loss of proprio- ception after back, knee, hip and ankle injuries22–24. Grigg and colleagues found that patients with total hip endoprothesis had different joint-position sense than healthy people25. In an investigation of equilibrium dis- orders, Bly and Sinnot found that patients with back in- jury had more frequent difficulties in standing on one leg or in holding the upright position, than controls26. Fur- thermore, the ability of repetitive body positioning was found to be worse in patients with back injury27. There are a number of investigations addressing dis- turbed proprioception after whiplash injury28–31, there is only one investigation from the University of Kansas Medical Center which refers to the loss of prorpioception in patients with neck injury measured using CMS18. Eleven patients aged 28 to 57 years with neck injury showed worse results than 11 controls. Our investigation included a larger number of younger subjects, which minimizes the risk of finding degenerative changes on the cervical spine. They all underwent the same study protocol. Our results showed that most patients failed to precisely rotate their heads left or right for 30° and that the results worsened in repeated attempts. This suggests that proprioceptive abilities in these patients deterio- rated with time. Apart from incorrect head rotation, these patients demonstrated incorrect movement of the head to the neutral position. The majority missed the neutral posi- tion by one or two degrees to the left or right. The results from our study coincide with the Univer- sity of Kansas Medical Center investigation, proving the hypothesis that people with whiplash injury have pro- prioceptive loss. The rehabilitation of these patients should include exercises for strengthening neck muscles and im- proving neck mobility and proprioception. 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Percent of patients and controls who returned the head to a neutral position of 0°and to other degrees of head rotation (1o, 2o and 3o). M. Uremovi} Zagreb Insurance Company, O`egovi}eva 16, 10000 Zagreb, Croatia e-mail: melita.uremovic@osiguranje-zagreb.hr POREME]AJ PROPRIOCEPCIJE NAKON WHIPLASH OZLJEDE S A @ E T A K Whiplash ozljede se obi~no javljaju u saobra}ajnim nezgodama. Osobe koje su zadobile takvu ozljedu mogu imati poreme}aj propriocepcije koji se ispoljava kao nemogu}nost to~nog odre|ivanja polo`aja glave. Cilj ovog istra`ivanja je bio analizirati poreme}aj propriocepcije u osoba s whiplash ozljedom. Sudjelovalo je 60 ispitanika s ozljedom vratne kralje`nice, u dobi od 20 do 50 godina. Kontrolna skupina se sastojala od 60 zdravih osoba stratificarnih po dobi i spolu. Za procjenu pokretljivosti vratne kralje`nice kori{ten je »Cervical Measurement System« (CMS), kojim se odre|uje sposobnost pojedinca da, nakon rotacije glave od 30o na desnu ili lijevu stranu, vrati glavu u po~etni polo`aj. Bolesnici s ozljedom vratne kralje`nice su imali zna~ajan poreme}aj propriocepcije u odnosu na zdrave ispitanike (p<0,001). Re- zultati podupiru hipotezu prema kojoj osobe s nedavnom ozljedom vratne kralje`nice imaju nepravilnu percepciju polo- `aja glave. Zbog toga njihova rehabilitacija treba uklju~ivati korekciju propriocepcije i koordinacije glave. M. Uremovi} et al.: Loss of Proprioception After Whiplash Injury, Coll. Antropol. 31 (2007) 3: 823–827 827