Subclinical Peroneal Neuropathy: A Common, Unrecognized, and Preventable Finding Associated With a Recent History of Falling in Hospitalized Patients

Article Figures & Data

Table 1

Characteristics of 100 Consecutively Admitted Medial Inpatients Aged 70 Years or Younger Deemed at Moderate to High Risk of Falling

Characteristic	No Peroneal Neuropathy (n = 33)	Subclinical Peroneal Neuropathy (n = 67)		P Value
Characteristic	No Peroneal Neuropathy (n = 33)	1 Positive Finding (n = 36)	≥2 Positive Findings (n = 31)	P Value
Age, median (IQR), y	50 (37–64)	57 (50–64)	60 (50–63)	.30
Female, No. %	18 (55)	22 (61)	19 (61)	.82
Vertigo, dizziness, balance disorder, No. %	15 (45)	13 (36)	25 (81)^a	.01
Impaired vision, No. %	7 (21)	7 (19)	10 (32)	.43
Osteoarthritis, No. %	6 (18)	14 (39)	14 (45.2)	.06
Stroke, No. %	5 (15)	7 (19)	5 (16)	.88
Recent significant weight loss, No. %	6 (18)	11 (30)	6 (19)	.40
Diabetes, No. %	8 (24)	10 (28)	13 (42)	.20
Peripheral neuropathy, No. %	13 (39)	13 (36)	19 (61)	.09
Heart disease, No. %	9 (27)	9 (25)	12 (39)	.44
Prior leg surgery, No. %	3 (9)	11 (31)	7 (23)	.09
Prior low back surgery, No. %	1 (3)	5 (14)	5 (16)	.19
Johns Hopkins Fall Risk score, median (IQR)^a	6 (6–9)	8 (6–11)	9 (7–11)^b	.02

Note: χ² or Kruskal-Wallis H, and Wilcoxan rank sum post-hoc used as appropriate.
↵a Ranging from 0 to 35, where a score of <6 = low risk, 6 to 13 = moderate risk, and >13 = high risk.
↵b Significant difference from no peroneal neuropathy.

Table 2

Univariate Associations of Subclinical Peroneal Neuropathy and Falling or High Fall Risk (ABC Score <67.0)

Examination Finding	Fall β Coefficient	Fall OR (95% CI)^a	P Value	ABC <67.0 β Coefficient	ABC <67.0 OR (95% CI)^a	P Value
Normal findings (reference)	…	1	.08	…	1	.04
1 Positive finding	0.693	2.00 (0.75–5.30)	.16	0.693	2.00 (0.75–5.30)	.16
≥2 Positive findings	1.153	3.17 (1.14–8.81)^b	.03	1.389	4.00 (1.40–11.42)^b	.01

Table 3

Association of Subclinical Peroneal Neuropathy With Falling Within a Multivariable Model

History and Physical Examination	β Coefficient	Fall OR (95% CI)^a	P Value
Normal findings on examination (reference)	…	1	.03
1 Positive finding	1.046	2.85 (0.97–8.38)	.06
≥2 Positive findings	1.547	4.70 (1.39–15.90)^b	.01
Osteoarthritis	−0.795	0.45 (0.18–1.16]	.10
Age >57 y	−0.667	0.51 (0.21–1.29)	.15
Vertigo, dizziness, or balance disorder	0.365	1.44 (0.57–3.67)	.44
Stroke	1.346	3.84 (1.10–13.47)^b	.04
Recent significant weight loss	−0.879	0.42 (0.14–1.21)	.42
Constant^c	−0.591	…	.23

OR = odds ratio.
Note: Nagelkerke R² = 0.215; overall model significance was P = .014
↵a Associations derived from multivariate logistic regression. Effects of diabetes, poor vision or blindness, peripheral neuropathy, and global weakness were examined and not found to confound the association of subclinical peroneal neuropathy and falling.
↵b Denotes statistical significance (P <.05).
↵c Intercept term of regression equation.

Table 4

Association of Subclinical Peroneal Neuropathy and Elevated Fall Risk (ABC Score <67.0) Within a Multivariable Model

History and Physical Examination	β Coefficient	OR (95% CI)^a	P Value
Normal findings on examination (reference)		1	.22
1 Positive finding	0.885	2.42 (0.77–7.66)	.13
≥2 Positive findings	0.952	2.60 (0.74–9.04)	.14
Global weakness	1.060	2.89 (0.99–8.42)	.05
Vertigo, dizziness, or balance disorder	0.991	2.69 (0.98–7.43)	.06
Osteoarthritis	−0.756	0.47 (0.17–1.31)	.15
Peripheral neuropathy	0.874	2.40 (0.92–6.26)	.08
Recent significant weight loss	−0.786	0.46 (0.15–1.38)	.17
Constant^b	−1.490	…	.01

ABC = Activities-specific Balance Confidence; OR = odds ratio.
Note: Nagelkerke R² = 0.270; overall model significance was P = .003.
↵a Associations derived from multivariate logistic regression. The effects of age, diabetes, and poor vision or blindness were examined and not found to confound this association.
↵b Intercept term of regression equation.

Table 5

Peroneal Neuropathy Assessment in Validated Inpatient Fall Risk Assessment Tools

Tool	Assessed Peroneal Nerve	How Peroneal Neuropathy Assessed	Other Factors Assessed
Berg balance⁴⁵	No	NA	Balance, transfers, strength
Conley Scale⁴⁶	Indirectly	Gait	History, cognition, vertigo, toileting
Johns Hopkins Fall Risk Assessment Tool¹²	Indirectly	Gait	Age, fall history, toileting, obstacles, cognition
Downton index⁴⁷	Indirectly	Gait, sensory examination	History, medications, cognition
Elderly Mobility Scale⁴⁸	Indirectly	Gait	Transfers, balance
Schmid Fall Risk Assessment⁴⁹	Indirectly	Gait	Mobility, cognition, incontinence, prior fall history, medications
STRATIFY^50,51	Indirectly	Gait	Fall history, agitation, vision, toileting, footwear, orthostatic supports, medications, environment

NA = not assessed; STRATIFY = St Thomas Risk Assessment Tool in Falling elderly inpatients.
Note: Among 7 inpatient fall risk assessment tools commonly used, no assessment tool directly assesses the peroneal nerve. Tools that assess gait are likely to miss subclinical peroneal neuropathy, which does not produce the characteristic steppage gait of overt peroneal neuropathy.