Clinimetrics of Freezing of Gait Anke H. Snijders, MD, 1 Maarten J. Nijkrake, MSc, 1 Maaike Bakker, MSc, 2 Marten Munneke, PhD, 1 Carina Wind, BHSc, 1 and Bastiaan R. Bloem, MD, PhD 1 * 1 Department of Neurology and Parkinson Center Nijmegen, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands 2 FC Donders Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands Abstract: The clinical assessment of freezing of gait (FOG) provides great challenges. Patients often do not realize what FOG really is. Assessing FOG is further complicated by the episodic, unpredictable, and variable presentation, as well as the complex relationship with medication. Here, we provide some practical recommendations for a standardized clinical approach. During history taking, presence of FOG is best ascertained by asking about the characteristic feeling of ‘‘being glued to the floor.’’ Detection of FOG is greatly facilitated by demonstrating what FOG actually looks like, not only to the patient but also to the spouse or other carer. History taking further focuses on the specific circumstances that provoke FOG and on its severity, preferably using stand- ardized questionnaires. Physical examination should be done both during the ON and OFF state, to judge the influence of treatment. Evaluation includes a dedicated ‘‘gait trajectory’’ that features specific triggers to elicit FOG (gait initiation; a narrow passage; dual tasking; and rapid 3608 axial turns in both directions). Evaluating the response to external cues has diagnostic importance, and helps to determine possible thera- peutic interventions. Because of the tight interplay between FOG and mental functions, the evaluation must include cog- nitive testing (mainly frontal executive functions) and judg- ment of mood. Neuroimaging is required for most patients in order to detect underlying pathology, in particular lesions of the frontal lobe or their connections to the basal ganglia. Various quantitative gait assessments have been proposed, but these methods have not proven value for clinical practice. Ó 2008 Movement Disorder Society Key words: freezing of gait; clinimetry; Parkinson’s disease Freezing of gait (FOG) is a curious type of gait dis- order. It is unusual because of its ‘‘episodic’’ character: the gait problem is sometimes there, but often it is not. Patients with FOG can experience debilitating episodes during which they are unable to start walking or, while walking, suddenly fail to continue moving forward. Because of this sudden and unpredictable nature, FOG is an important cause of falls and injuries. 1 FOG is a challenge for clinicians. Many patients in- advertently deny having FOG because they do not properly know what actual freezing looks like. Even when patients report having FOG at home, the phe- nomenon is notoriously difficult to elicit in the clinical setting. Apparently, excitement associated with the doctor’s visit or the patient’s extra attention to gait during physical examination can temporarily suppress FOG (a form of ‘‘kinesia paradoxa’’). Another explana- tion is that FOG, which is typically provoked while walking in tight quarters, 2 is less likely to occur in a widely spaced hospital corridor than at home in a crammed living room. This failure to demonstrate the problem that hinders them so much at home is very frustrating for patients and carers. It is also inconven- ient for doctors who need to base their clinical man- agement decisions based on observations in the exami- nation room. FOG provides equally great challenges for research- ers. In a formal testing environment (e.g. a gait labora- tory), it is even more difficult to elicit FOG. 3 This makes it hard to evaluate the underlying pathophysiol- *Correspondence to: Dr. Bastiaan R. Bloem, Parkinson Center Nijmegen (ParC), Department of Neurology, 935, Radboud Univer- sity Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands. E-mail: b.bloem@neuro.umcn.nl No potential conflict of interest. Received 20 September 2007; Revised 8 April 2008; Accepted 27 April 2008 Published online 25 July 2008 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/mds.22144 S468 Movement Disorders Vol. 23, Suppl. 2, 2008, pp. S468–S474 Ó 2008 Movement Disorder Society