Gait analysis in idiopathic normal pressure hydrocephalus--which parameters respond to the CSF tap test?

Diagnosing idiopathic normal-pressure hydrocephalus

OBJECTIVE

The precise incidence and prevalence of idiopathic normal-pressure hydrocephalus (INPH) is not known, and evidence-based clinical diagnostic criteria have not been developed previously. This report contains evidence-based guidelines for clinical diagnosis of INPH that are intended to facilitate future epidemiological studies of INPH, promote earlier and more accurate diagnosis, and ultimately improve treatment outcome.

METHODS

The criteria for the diagnosis of INPH are based on evidence from the medical literature, supplemented as necessary by expert opinion. From 1966 to 2003, 653 publications on "normal-pressure hydrocephalus" were cited in MEDLINE, including 29 articles that met the more stringent criteria of including "idiopathic normal-pressure hydrocephalus" in their title. Additional studies were considered that explicitly identified INPH cases and/or specified the criteria for a diagnosis of INPH. Studies were graded according to the class of evidence and results summarized in evidentiary tables. For issues of clinical relevance that lacked substantive evidence from the medical literature, the opinions of consulting experts were considered and contributed to "Options."

RESULTS

Evidence-based guidelines for the clinical diagnosis of INPH have been developed. A detailed understanding of the range of clinical manifestations of this disorder and adherence to practice guidelines should improve the timely and accurate recognition of this disorder.

CONCLUSION

It is recommended that INPH be classified into probable, possible, and unlikely categories. We hope that these criteria will be widely applied in clinical practice and will promote greater consistency in patient selection in future clinical investigations involving INPH.

Correlation of midbrain diameter and gait disturbance in patients with idiopathic normal pressure hydrocephalus

BACKGROUND AND PURPOSE

Although gait disturbance is an important feature of idiopathic normal pressure hydrocephalus (NPH), only tentative theories have been offered to explain its pathophysiology. It has been suggested that the mesencephalic locomotor region is the anatomical substrate for the development of the hypokinetic NPH gait. To investigate this possibility, we evaluated the correlation between gait disturbance and midbrain diameter.

METHODS

We enrolled 21 patients with NPH and 20 age-matched control subjects for the study. The maximal diameter of the midbrain and pons, and the width of the lateral and third ventricles were measured using midsagittal T1-weighted MRI and axial T2-weighted MRI, respectively. Gait disturbance, cognitive dysfunction, and incontinence were semiquantified.

RESULTS

The maximal midbrain diameter was significantly smaller in the NPH group than in the controls (14.8 +/- 0.9 vs. 17.1 +/- 0.7 mm, p < 0.001). There were inverse correlations between the midbrain diameter and the widths of the two ventricles (r = -0.562, p = 0.008 for the third ventricle, and r = -0.510, p = 0.018 for the lateral ventricle). The severity of gait disturbance was negatively correlated with the midbrain diameter (r = -0.598, p = 0.004), but the degree of cognitive dysfunction and incontinence showed no significant correlation with midbrain diameter or ventricular width.

CONCLUSIONS

This study suggests that midbrain atrophy is significantly associated with gait disturbance in NPH.

Quantification of human motion: gait analysis-benefits and limitations to its application to clinical problems

The technology supporting the analysis of human motion has advanced dramatically. Past decades of locomotion research have provided us with significant knowledge about the accuracy of tests performed, the understanding of the process of human locomotion, and how clinical testing can be used to evaluate medical disorders and affect their treatment. Gait analysis is now recognized as clinically useful and financially reimbursable for some medical conditions. Yet, the routine clinical use of gait analysis has seen very limited growth. The issue of its clinical value is related to many factors, including the applicability of existing technology to addressing clinical problems; the limited use of such tests to address a wide variety of medical disorders; the manner in which gait laboratories are organized, tests are performed, and reports generated; and the clinical understanding and expectations of laboratory results. Clinical use is most hampered by the length of time and costs required for performing a study and interpreting it. A "gait" report is lengthy, its data are not well understood, and it includes a clinical interpretation, all of which do not occur with other clinical tests. Current biotechnology research is seeking to address these problems by creating techniques to capture data rapidly, accurately, and efficiently, and to interpret such data by an assortment of modeling, statistical, wave interpretation, and artificial intelligence methodologies. The success of such efforts rests on both our technical abilities and communication between engineers and clinicians.