Clinical Neurology and Neurosurgery 126 (2014) 30–34

Contents lists available at ScienceDirect

Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro

Magnetic resonance imaging predictors for respiratory failure after cervical spinal cord injury Yu-Hua Huang a,b , Chien-Yu Ou c,∗ a b c

Department of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan Department of Surgery, Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan

a r t i c l e

i n f o

Article history: Received 8 June 2014 Received in revised form 3 August 2014 Accepted 9 August 2014 Available online 27 August 2014 Keywords: Spinal cord injury Respiratory failure ASIA classification MRI

a b s t r a c t Background: Patients after cervical spinal cord injury (CSCI) may experience ventilator-dependent respiratory failure during the acute hospitalization period. The aim of the study is to identify imaging factors that predict respiratory failure after acute CSCI. Materials and methods: We enrolled 108 patients diagnosed with CSCI in 4 years. The definition of respiratory failure consisted of the requirement of a definitive airway and the assistance of mechanical ventilation. Objective neurological function was determined using the classification of the American Spinal Injury Association (ASIA). We evaluated the characteristics of magnetic resonance imaging (MRI) of the cervical spine. Results: Respiratory failure occurred in 8 (7.40%) of 108 CSCI patients. The ASIA classification of the 108 patients were A (6), B (3), C (60), D (27), and E (12), and the 8 respiratory failure patients were A (3), B (1), and C (4). Seven of 8 patients with respiratory failure and 78 of 100 patients without respiratory failure had a neurological level of C5 or above by the ASIA standards (p = 1.000). The imaging level of injury at C3 by MRI was identified in 5 of 8 patients that developed respiratory failure and more frequent than injury at the lower cervical levels (p < 0.001). The presence of spinal cord edema was another predictor of respiratory failure (p = 0.009). Conclusion: MRI can accurately localize CSCI and identify those patients at risk of respiratory failure. Imaging level of injury at C3 and presence of spinal cord edema are both predictors. To prevent secondary cord injury from prolonged hypoxia and facilitate pulmonary care, definitive airways should be established early in high risk patients. © 2014 Elsevier B.V. All rights reserved.

1. Introduction Acute spinal cord injury is one of the causes of morbidity and mortality in teenagers and adults, and approximately one-third of these patients have cervical spinal cord injury (CSCI) [1]. Pulmonary dysfunction accounts for the largest proportion of complications after a spinal insult and includes ventilation failure, atelectasis, pneumonia, and pleural effusion [2–4]. The respiratory sequelae result from a variety of mechanisms, consisting of expiratory muscle weakness, retained secretions, bronchial mucus hypersecretion, ileus with embarrassment of diaphragmatic

∗ Corresponding author at: Department of Surgery, Kaohsiung Armed Forces General Hospital, No. 2, Zhongzheng 1st Road, Lingya District, Kaohsiung City, Taiwan. Tel.: +886 7 7496751; fax: +886 7 7496751. E-mail address: [email protected] (C.-Y. Ou). http://dx.doi.org/10.1016/j.clineuro.2014.08.015 0303-8467/© 2014 Elsevier B.V. All rights reserved.

excursion, an increased risk of aspiration of gastric contents, associated rib fractures, or thoracoabdominal trauma. As a result, patients who sustain CSCI may require definitive airway protection with the assistance of mechanical ventilators during their acute hospitalization period. Predictors of the necessity for respiratory support in the CSCI population have not been well analyzed. The ability to identify who will need a definitive airway can allow for earlier management and the initiation of mechanical ventilation under controlled circumstances rather than as an emergency. It theoretically lowers the incidence of secondary spinal cord injury related to prolonged hypoxia or neck trauma from violent intubation. Therefore, in this study, we performed a retrospective chart review of patients diagnosed with CSCI and evaluated their clinical features and neurological measurements. Furthermore, the use of MRI, a valuable modality for assessing CSCI in neurosurgical practice, can offer a detailed image of the spinal cord as well as the spinal ligaments, intervertebral discs, and paraspinal

Y.-H. Huang, C.-Y. Ou / Clinical Neurology and Neurosurgery 126 (2014) 30–34

soft tissues. We investigated the characteristics of MRI of the cervical spine that are predictive of respiratory failure following CSCI.

2. Materials and methods Over a period of 4 years (2001–2005), 111 patients who suffered from CSCI were admitted to Kaohsiung Chang Gung Memorial Hospital in Taiwan that provides both primary and tertiary referral care to patients. The patients received complete neurological examinations and cervical spinal images from neurosurgeons and radiologists. The criterion for a definite diagnosis of CSCI was an insult via trauma to the cervical spinal cord resulting in a change, either temporary or permanent, in its normal motor, sensory, or autonomic functions. Patients were excluded if they were comatose; the duration between injury and admission was more than fourteen days; or the MRI of the cervical spine could not be assessed because of missing data or poor imaging quality. In total, 108 adult patients who had suffered from acute CSCI were enrolled for analysis. The study protocol on CSCI was approved by the Institutional Review Committee on Human Research at the Chang Gung Memorial Hospital. The definition of respiratory failure after CSCI during the acute hospitalization period was: (1) a requirement for a definitive airway via one of the following: orotracheal intubation, nasotracheal intubation, or tracheostomy and (2) the need for mechanical ventilation. When intubation with ventilatory assistance was required for the operation or for immediate post-operative recovery and the patients were smoothly extubated within 3 days of the operation, this condition was not coded as respiratory failure for the purposes of this study. The neurological status of each patient was recorded objectively at the time of admission, using the ASIA classification system. The ASIA scale includes five categories: A, complete, with no motor or sensory function; B, incomplete with preservation of sensory function below the level of injury, but motor function is not preserved; C, incomplete with preservation of motor function below the level of the neurologic injury, but at least 50% of this function is a muscle grade less than 3; D, incomplete with preservation of motor function below the level of the neurologic injury with at least 50% of this function being a muscle grade 3 or greater; and E, normal motor and sensory functions. In addition, the neurologic level of injury refers to the most caudal segment of the spinal cord with normal sensory and motor functions on both sides of the body. According to the ASIA standards, C5 supplies elbow flexors, C6 supplies wrist extensors, C7 supplies elbow extensors, C8 supplies finger flexors (flexor digitorum profundus) to the middle finger, and T1 supplies small finger abductors (abductor digiti minimi) [5,6]. All patients received cervical radiographs and MRI after arrival at the hospital. Follow-up images were performed if deterioration of the neurological deficits was noted, and after neurosurgical procedures were performed. In our institution, high-resolution MRI scans of the cervical spine were performed using a 1.5 T whole-body system (GE Medical Systems, Signa Horizon, Lx 8.3, Milwaukee, USA) and Gyroscan Intera (Philips Medical System, Netherlands). The T1and T2-weighted axial and sagittal views of the cervical spinal MRI were interpreted by the following findings: herniated intervertebral disc (HIVD); fractures of the cervical spine at the vertebral body, lamina, or other bony structures; dislocation or subluxation of the cervical spine from its original alignment; spinal cord edema identified when T2-weighted images showed hyperintense changes of the spinal cord; spinal cord compression by bone fragments, ruptured intervertebral disc, epidural hematoma, or other mass lesions; and imaging level of the injury was defined as the

31

highest or most rostral segment of spinal cord edema or spinal cord compression. When the timing was appropriate, patients received intravenous methylprednisolone administration based on the National Acute Spinal Cord Injury Study II protocol [7]. Surgery was indicated if the neurological deficits were compatible with the abnormal findings of the MRI scans. The choice of the operative procedure depended on the imaging features and clinical presentation. In patients with HIVD, anterior cervical discectomy and inter-body fusion with an iliac bone graft or cage were performed. We also implemented fixation using plates and screws as we were concerned about traumatic instability of the cervical spine. In patients with spinal cord compression from posterior structures or severe spinal cord swelling with relative narrowing of the spinal canal, decompressive laminectomy was chosen. The characteristics and circumstances of the 108 patients were documented, including age, gender, systemic underlying diseases (hypertension, diabetes mellitus, alcoholism, etc.), mechanisms of CSCI, presenting symptoms, and Glasgow Coma Scale (GCS). The associated thoracic or lung trauma comprised rib fracture, pneumothorax/hemothorax, or lung contusion. We defined pneumonia as evidence of increased secretions with a positive sputum culture and radiographical lung consolidation or infiltration in the presence of a fever (>38 ◦ C). The placement of a tracheostomy was determined by the neurosurgeons when the patients were unable to be weaned from mechanical ventilation in the short term. The length of hospital stay and intensive care unit (ICU) stay were also recorded. The patients were followed-up at the outpatient department after discharge, and received a series of neurological examinations and/or MRI studies. Data were analyzed using SPSS version 12.0 (SPSS Inc., Chicago, IL). Categorical variables were analyzed by the chi-square test or Fisher’s exact test. Continuous variables were assessed using the Student’s t-test or Mann–Whitney U-test. A p value of less than 0.05 was considered statistically significant.

3. Results The 108 patients (85 males and 23 females) diagnosed with CSCI had a mean age of 52.02 ± 15.75 years. The different mechanisms of CSCI comprised 79 cases of traffic accidents, 27 cases of falls, and 2 cases of collision with heavy objects. The associated thoracic or lung trauma included 1 rib fracture, 2 hemothorax, and 1 lung contusion. Respiratory failure after CSCI occurred in 8 (7.4%) of the 108 patients. Table 1 contains the clinical features of the eight patients suffering from respiratory failure. In this study, the patients with CSCI were subdivided into two groups based on the presence or absence of respiratory failure during the period of acute hospitalization. The baseline characteristics of the 2 groups are compared below and shown in Table 2. Differences in the gender (p = 1.000) and mean age (p = 0.169) between the two groups were not statistically significant. There were no differences in traumatic mechanisms (p = 0.921) and associated injury of the thoracic cage or lungs (p = 0.268). The mean GCS at admission was 14.50 ± 1.07 in the respiratory failure patients and 14.87 ± 0.53 in the other patients (p = 0.105). The prevalence of underlying diseases including hypertension, diabetes mellitus, and alcoholism were not significantly different between the two groups. According to the ASIA classification, the case numbers of the ASIA scales A, B, C, D, and E were 6, 3, 60, 27, and 12, respectively. Overall, six patients had complete spinal cord injuries, while the other 102 patients had incomplete spinal cord injuries. Among the 8 patients with subsequent respiratory failure, 3, 1, and 4 patients belonged to ASIA A, B, and C, respectively. The 100 patients with

32

Y.-H. Huang, C.-Y. Ou / Clinical Neurology and Neurosurgery 126 (2014) 30–34

Table 1 Summary of 8 patients with respiratory failure after CSCI. Patient

Gender, age (yr)

Mechanism of trauma

Type of cervical spine injury

ASIA classification

Definitive airway

Duration of ventilation (day)

Pneumonia

Associated injury

1 2

M, 56 M, 19

Fall MVC

C C

Tracheostomy Tracheostomy

20 23

Yes Yes

– –

3 4

M, 64 M, 28

MVC MVC

C C

Tracheostomy NTI

9 20

Yes Yes

– –

5

M, 80

MVC

A

Tracheostomy

7

Yes



6

M, 31

Fall

C3-4 HIVD C3 epidural hematoma C3-5 cord swelling C4-5 fracturedislocation C3-4 HIVD C5-6 fracturedislocation C6 compression fracture C5-6 kyphosis

A

Tracheostomy

14

No

Skull fracture

No Yes

Subdural hemorrhage Hemothorax –

7 8

F, 39 M, 40

MVC MVC

C3-4 HIVD C7 compression fracture C6-7 subluxation

C A

NTI Tracheostomy

14 8

MVC: motor vehicle crash; ASIA: American Spinal Injury Association; NTI: nasotracheal intubation.

normal respiratory function included 3 of ASIA A, 2 of ASIA B, 56 of ASIA C, 27 of ASIA D, and 12 of ASIA E patients. This difference in the ASIA scales between the two groups was statistically significant (p < 0.001). Regarding the neurologic level of injury for the ASIA standards, 7 of 8 patients in the respiratory failure group and 78 of 100 patients in the other group had levels of C5 or above. There were no significant differences between the two groups (p = 1.000). The summary of CSCI patients stratified by their ASIA classification, with or without respiratory failure, is shown in Table 3. Among the 108 patients with CSCI, MRI of the cervical spine at admission revealed the presence of spinal cord edema in all of the 8 respiratory failure patients and 53 of the 100 patients without respiratory failure. This difference was statistically significant (p = 0.009). The other features of the MRI obtained in the 2 groups showed no significant differences for the presence of spinal cord

Yes N (%)100 (100)

No N (%) 8 (100)

p-Value

7 (87.5) 44.63 ± 20.45

78 (78.0) 52.61 ± 15.29

1.000 0.169

compression (p = 1.000), fracture of the cervical spine (p = 0.223), dislocation or subluxation of the cervical spine (p = 0.105), and HIVD (p = 0.475). As for the imaging level of injury determined using MRI, the case numbers of the C2, C3, C4, C5, C6, and C7 levels were 0, 5, 1, 1, 0, and 1 among those who had respiratory failure, and 1, 7, 43, 27, 18, and 4 among those who had no respiratory failure, respectively. There was a statistically significant intergroup difference in the imaging level of CSCI (p < 0.001). The findings of MRI in the two groups are compared in Table 4. All the 8 patients with respiratory failure and 75 of the 100 patients without respiratory failure received methylprednisolone administration under the National Acute Spinal Cord Injury Study II protocol. There was no significant difference between the two groups for the administration of methylprednisolone (p = 0.194). In addition, whether or not the patients underwent an operation for cervical spine injury was not significantly different between the two groups (p = 1.000). Pneumonia was found in 6 of 8 respiratory failure patients as well as 1 of 100 patients having no respiratory failure, and this difference was statistically significant (p < 0.001). The mean hospital stay in the respiratory failure group was 55.88 ± 25.00 days, compared with 22.17 ± 19.61 days in the other group (p < 0.001). The mean ICU stay was 28.63 ± 18.15 and 1.38 ± 2.79 in the cases with and without respiratory failure, respectively, and this difference was statistically significant (p = 0.004).

0 (0) 1 (12.5) 0 (0)

11 (11.0) 9 (9.0) 10 (10.0)

1.000 0.553 1.000 0.921

Table 3 Comparisons of the ASIA classification in the presence or absence of respiratory failure.

6 (75.0) 2 (25.0) 0 (0)

73 (73.0) 25 (25.0) 2 (2.0)

1 (12.5)

3 (3.0)

0.268

14.50 ± 1.07

14.87 ± 0.53

0.105

8 (100)

75 (75.0)

0.194

5 (62.5)

61 (61.0)

1.000

Table 2 Comparisons of the baseline clinical features in the presence or absence of respiratory failure. Presence of respiratory failure

Gender (male) Mean age (year) Underlying disease Hypertension Diabetes mellitus Alcoholism Mechanisms of trauma Traffic accident Fall accident Collision with heavy objects Associated thoracic/lung injury Mean GCS at admission Treatment of CSCI Use of methylprednisolone Operation of cervical spine Presence of pneumonia Mean hospital stay (day) Mean ICU stay (day) *

p < 0.05.

6 (75.0) 55.88 ± 25.00

1 (1.0) 22.17 ± 19.61

28.63 ± 18.15

1.38 ± 2.79

Presence of respiratory failure

Magnetic resonance imaging predictors for respiratory failure after cervical spinal cord injury.

Patients after cervical spinal cord injury (CSCI) may experience ventilator-dependent respiratory failure during the acute hospitalization period. The...
317KB Sizes 0 Downloads 10 Views