Chiari malformation type 1 (CM-I) is a common and often debilitating neurologic disease. Reliable evaluation of treatments has been hampered by inconsistent use of clinical outcome measures. A variety of outcome measurement tools are available, although few have been validated in CM-I. The recent development of the Chicago Chiari Outcome Scale and the Chiari Symptom Profile provides CM-I-specific instruments to measure outcomes in adults and children, although validation and refinement may be necessary.
Key points
- •
Several commonly used general outcome measures have been used to evaluate treatment outcomes for patients with Chiari malformation type 1 (CM-I).
- •
Of the general quality of life and disability scales, the Neck Disability Index (NDI) and the Short Form (SF)-12 have been shown to have the most validity in patients with CM-I.
- •
Of the disease-specific outcome instruments, scales designed for use in patients with cervical spine problems, such as the modified Japanese Orthopaedic Association (JOA) score, have been used in the CM-I population. Although several of these scales adequately assess neurologic function related to CM-I, none assess all aspects of CM-I symptoms.
- •
Chiari-specific scales, such as the Chicago Chiari Outcome Scale (CCOS) and the Chiari Symptom Profile, assess the aspects of CM-I disease and treatment outcomes more completely than previous instruments.
Introduction
CM-I is a common and often debilitating neurologic condition and may result in a variety of signs and symptoms, ranging from headache to brainstem compromise. According to some estimates, CM-I is identified in almost 1% of all brain and cervical spine MRI studies, although recent evidence suggests that in children the MRI prevalence may be closer to 4%. Although many individuals with radiographic evidence of CM-I are asymptomatic, the clinical manifestations of the disease are broad, complicating efforts to guide patient management and study treatment response. Complicating matters, there is no consensus on the decision to intervene surgically. In addition, various investigators have advocated for and against technical variations on foramen magnum decompression with varied opinions but without true experimental conditions.
Assessment of outcomes is complicated by the lack of validated outcome measures specific to CM-I. In recent years, patient-centered approaches to clinical research have become more prominent, and the emphasis on developing and validating rigorous outcome instruments has grown. Increasing research efforts in CM-I have focused on comparative effectiveness research and on disease-specific evaluation of clinical outcomes. Despite this increased focus on improved research methodology in neurosurgery and other clinical fields, the use of subjective treatment measurement tools remains. This review briefly discusses the various approaches of reporting outcomes in the treatment of patients with CM-I.
The outcome measures reviewed in this article are divided into several broad categories: (1) providing gestalt impression of overall or symptom-specific improvement, (2) using validated quality-of-life (QoL) and disability scores designed to quantify general level of function or disability, (3) using disease-specific, quantifiable methodology to assign numerical scores to symptom status. The first category is largely provider reported, whereas the last 2 categories incorporate patient-centered outcomes. Given the increasing focus on patient-reported outcomes, future studies should consider use of validated patient-centered outcome measures at the expense of gestalt evaluations. For the purposes of this discussion, criterion validity is the concordance of measurements between the instrument and a well-established outcome measure.
General outcome measures
Before the development of CM-I-specific outcome instruments, many studies used a general gestalt method of determining improvement in clinical status. With minor variations, this method of outcome assessment assigns a patient to improved, stable, or worse categories after therapeutic intervention and has been used in a multitude of case series. Although this method of outcome measurement is widely used, it suffers from significant shortfalls. First, the wide variety of symptoms with which patients with CM-I present creates a heterogeneous constellation of symptomatology. Because of the many domains in which symptoms might affect a patient, a simple unidimensional classification scheme does not often suffice to describe fully the change in the clinical signs and symptoms patients with CM-I may face. Second, the signs and symptoms patients experience may affect their outcome differently, a fact not assessed with a simple outcome measure. Third, gestalt impressions do have poor internal or external validity, so comparison of outcomes between or within institutions is problematic when using only this method. Although these limitations are significant, gestalt assessments continue to be used clinically because of convenience and ease of use. A related but more complete method of reporting outcomes includes use of symptom-specific outcomes, although this method also entails use of nonspecific categories similar to the overall gestalt method of outcome assessment.
Introduction
CM-I is a common and often debilitating neurologic condition and may result in a variety of signs and symptoms, ranging from headache to brainstem compromise. According to some estimates, CM-I is identified in almost 1% of all brain and cervical spine MRI studies, although recent evidence suggests that in children the MRI prevalence may be closer to 4%. Although many individuals with radiographic evidence of CM-I are asymptomatic, the clinical manifestations of the disease are broad, complicating efforts to guide patient management and study treatment response. Complicating matters, there is no consensus on the decision to intervene surgically. In addition, various investigators have advocated for and against technical variations on foramen magnum decompression with varied opinions but without true experimental conditions.
Assessment of outcomes is complicated by the lack of validated outcome measures specific to CM-I. In recent years, patient-centered approaches to clinical research have become more prominent, and the emphasis on developing and validating rigorous outcome instruments has grown. Increasing research efforts in CM-I have focused on comparative effectiveness research and on disease-specific evaluation of clinical outcomes. Despite this increased focus on improved research methodology in neurosurgery and other clinical fields, the use of subjective treatment measurement tools remains. This review briefly discusses the various approaches of reporting outcomes in the treatment of patients with CM-I.
The outcome measures reviewed in this article are divided into several broad categories: (1) providing gestalt impression of overall or symptom-specific improvement, (2) using validated quality-of-life (QoL) and disability scores designed to quantify general level of function or disability, (3) using disease-specific, quantifiable methodology to assign numerical scores to symptom status. The first category is largely provider reported, whereas the last 2 categories incorporate patient-centered outcomes. Given the increasing focus on patient-reported outcomes, future studies should consider use of validated patient-centered outcome measures at the expense of gestalt evaluations. For the purposes of this discussion, criterion validity is the concordance of measurements between the instrument and a well-established outcome measure.
General outcome measures
Before the development of CM-I-specific outcome instruments, many studies used a general gestalt method of determining improvement in clinical status. With minor variations, this method of outcome assessment assigns a patient to improved, stable, or worse categories after therapeutic intervention and has been used in a multitude of case series. Although this method of outcome measurement is widely used, it suffers from significant shortfalls. First, the wide variety of symptoms with which patients with CM-I present creates a heterogeneous constellation of symptomatology. Because of the many domains in which symptoms might affect a patient, a simple unidimensional classification scheme does not often suffice to describe fully the change in the clinical signs and symptoms patients with CM-I may face. Second, the signs and symptoms patients experience may affect their outcome differently, a fact not assessed with a simple outcome measure. Third, gestalt impressions do have poor internal or external validity, so comparison of outcomes between or within institutions is problematic when using only this method. Although these limitations are significant, gestalt assessments continue to be used clinically because of convenience and ease of use. A related but more complete method of reporting outcomes includes use of symptom-specific outcomes, although this method also entails use of nonspecific categories similar to the overall gestalt method of outcome assessment.
Quality of life and disability scales
Because of the absence of robust CM-I-specific measures, some investigators have used general QoL measures not focused on any single disease or have adopted disability scales developed to study conditions other than CM-1 ( Table 1 ). Some of these tools focus on evaluation of general health and are applicable to a wide range of diseases. For instance, the Euro-Qol-5d, Karnofsky Performance score, Rankin score, SF-12 and SF-36, sickness impact profile, and visual analog scale for disease impact on daily life have each been used in clinical research on CM-I but were designed to measure general QoL and disability rather than specific conditions and outcomes pertinent to CM-I. Each of these has been used once in clinical studies of CM-I.
| Name of Outcome Tool | Age-group Studied | CM-I Validity | Reliability in CM-I |
|---|---|---|---|
| Euro-Qol-5d | Adults | Yes | No |
| Headache Disability Index | Adults | No | No |
| Karnofsky Performance score | Adults & children | No | No |
| Neck Disability Index | Adults | Yes | No |
| Noudel et al.’s adapted functional grading system | Adults & children | No | No |
| Rankin scale | Adults & children | No | No |
| Short Form-12 | Adults | Yes | No |
| Short Form-36 | Adults, unclear if children as well | No | No |
| Sickness impact profile | Adults & children | No | No |
| Visual analog scale for disease impact on daily life | Adults & children | No | No |
| Zung Self-Rating Depression scale | Adults | Yes | No |
In addition to such instruments evaluating general function, several tools specifically designed to study diseases such as depression, cervical spine, and headache have been used to assess aspects of common CM-I symptoms quantitatively. Although several of these instruments have criterion validity, none of these instruments offer a comprehensive evaluation of the disease-specific outcomes relevant to patients with CM-I. In addition, the validity of Euro-Qol-5d, NDI, SF-12, and Zung Self-Rating Depression scale was assessed in a single study in adult patients.
Although not offering a complete view of CM-I outcomes, several of these general QoL and domain-specific tools have shown criterion validity, that is, concordance with well-established outcome measures, in patients with CM-I. Specifically, NDI and SF-12 show excellent validity for disability and QoL, respectively. These patient-reported outcome measures have been validated in other populations and can play an important role in quantifying outcomes in CM-I. These measures are briefly described.
Neck Disability Index
The NDI was adapted from 2 earlier measurement tools designed for use in low back pain. The NDI ( Table 2 ) scores 10 categories, assigning a numerical value from 0 to 5 in each category. Higher scores denote more severe dysfunction. The NDI allows self-rating of disability related to neck pain and has been in wide use. In one study assessing validity of response instruments, the NDI showed the highest criterion validity among several common tools for assessing pain and disability.
| Characteristic | Score | |||||
|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | |
| Pain | No pain | Very mild | Moderate | Fairly severe | Very severe | Worst imaginable |
| Personal care (washing, dressing) | No limits | No limits but causes pain | Painful, slow and careful | Requires some help, but can manage most care | Requires help every day in most aspects | Cannot get dressed, washes with difficulty, stays in bed |
| Lifting | Heavy weights without pain | Heavy weights with pain | Limited with heavy weights, cannot pick up off floor | Pain prevents lifting heavy weights but can manage light weights | Can lift very light weights only | Cannot lift anything |
| Reading | Unlimited | Unlimited with slight pain in neck | Unlimited with moderate pain | Limited because of moderate neck pain | Difficulty reading because of severe pain | Cannot read because of pain |
| Headaches | None | Slight, infrequent | Moderate, infrequent | Moderate, frequent | Severe, frequent | Nearly constant |
| Concentration | Full without limits | Full with slight difficulty | Fair difficulty | A lot of difficulty | Great difficulty | Cannot concentrate |
| Work | Unlimited | Only usual work | Most of usual work | Cannot do usual work | Hardly any work | Cannot work |
| Driving | Can drive without any pain | Can drive with slight pain | Can drive with moderate pain | Cannot drive because of moderate pain | Can hardly drive because of severe pain | Cannot drive |
| Sleeping | No trouble | Slight disturbance (<1 h sleepless) | Mild disturbance (1–2 h sleepless) | Moderate disturbance (2–3 h sleepless) | Great disturbance (3–5 h sleepless) | Complete disturbance (5–7 h sleepless) |
| Recreation | Can perform all activities | All activities with some pain | Most activities, limited by neck pain | A few of normal activities, limited by neck pain | Hardly any recreation because of neck pain | No recreational activities |
Related posts:
Definitions and Anatomic Considerations in Chiari I Malformation and Associated Syringomyelia
Pathogenesis and Cerebrospinal Fluid Hydrodynamics of the Chiari I Malformation
Prevalence of Chiari I Malformation and Syringomyelia
Surgical History of Sleep Apnea in Pediatric Patients with Chiari Type 1 Malformation
Craniovertebral Junction Instability in the Setting of Chiari I Malformation
Complex Chiari Malformations in Children
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
