Table 4.

Predictive values for combinations of significant clinical signs for a large syrinx (≥ 4 mm)

Unprovoked scratching Q2 OR scratching neck or shoulder Q3 OR phantom scratching Q5	Aggravation of scratching during emotional arousal Q6	Aversion to touch on head, neck or shoulder Q7	A preferred head posture during sleep Q13	PPV	NPV
X	X			0.74	0.58
X		X		0.82	0.52
X			X	0.82	0.52
X	X	X		0.77	0.53
X	X		X	0.88	0.51
X		X	X	0.91	0.49
X	X	X	X	0.79	0.57

Positive and negative predictive values for the clinical signs unprovoked scratching ^Q2 or scratching neck or shoulder ^Q3 or phantom scratching ^Q5 in combination with the other significant clinical signs. NPV, negative predictive value; PPV, positive predictive value; Q, question number referring to the questionnaire