Original communication

Journal of Neurology

, Volume 245, Issue 12, pp 797-802

Diagnosis of “non-organic” limb paresis by a novel objective motor assessment: the quantitative Hoover’s test

  • I. ZivAffiliated withDepartment of Neurology, Rabin Medical Centre, 49100 Petah-Tiqva, Israel Tel.: +972-3-9376358 Fax: +972-3-9223352
  • , Ruth DjaldettiAffiliated withDepartment of Neurology and the Felsenstein Research Institute, Rabin Medical Centre, Petah-Tiqva, and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
  • , Yoseph ZoldanAffiliated withDepartment of Neurology and the Felsenstein Research Institute, Rabin Medical Centre, Petah-Tiqva, and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
  • , Marian AvrahamAffiliated withDepartment of Neurology and the Felsenstein Research Institute, Rabin Medical Centre, Petah-Tiqva, and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
  • , Eldad MelamedAffiliated withDepartment of Neurology and the Felsenstein Research Institute, Rabin Medical Centre, Petah-Tiqva, and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel

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Abstract

The differentiation of “non-organic” limb weakness from genuine paralysis is sometimes difficult in neurological practice. To address this problem, we developed a computerized quantitative method, based on the Hoover’s test principle, that determines the extent of involuntary limb activation when contralateral movement is performed. Measurements of hip or arm extension isometric force are performed during direct maximal voluntary effort and during contralateral hip flexion. Maximal involuntary/voluntary force ratio (IVVR) is calculated. IVVR of the lower limbs in ten healthy subjects was 0.614, 0.044 (mean, SEM). Similar results were obtained from seven patients with genuine weakness and in the non-affected limbs of nine patients with “non-organic” mono- or hemiparesis. In contrast, IVVR in the affected limbs in the “non-organic” group was markedly increased (2.48, 0.61; P < 0.001). The same pattern was elicited in the upper limbs (2.27, 0.46 vs 0.406, 0.06; P < 0,001). We conclude that Hoover’s sign in “non-organic” paralysis is a preservation or increase of a normal synkinetic phenomenon. Quantitative measurement of the IVVR can serve as a useful ancillary test in diagnosing non-organic weakness in either lower or upper limbs.

Key words Non-organic Paralysis Diagnosis Hoover Quantitative