Neuropathic pain in peroneal nerve entrapment at the fibular head

Peroneal neuropathy at the fibular head (PNFH) is a mononeuropathy that typically presents with drop foot and sensory abnormalities over the skin area innervated by the peroneal nerve.

Objective

The aim of the present study was to evaluate neuropathic pain in patients with PNFH.

Methods

Patients with clinical and electrodiagnostic features consistent with PNFH associated with weight loss, leg postures, or prolonged sleep were included in the present retrospective cohort study. Nerve conduction studies were performed in the bilateral lower extremities of all patients. The Leeds assessment of neuropathic symptoms and signs scale (LANSS) was applied to all patients.

Results

Thirty-two PNFH patients (78% males) were included in the study. The LANSS score in the majority of patients was lower than 12. There was 1 patient with a LANSS score of 12. The electrodiagnostic features of 16 patients were compatible with axonal degeneration. The mean LANSS scores of PNFH patients with and without axonal degeneration were 4.3 ± 3.7 and 5.2 ± 2.9, respectively (p = 0.255).

Conclusion

The present study showed that neuropathic pain is a rare symptom in patients with PNFH associated with weight loss, leg postures, or prolonged sleep.

Keywords
Electrodiagnosis; Neural Conduction; Neuralgia; Peroneal Nerve

Clinical feature		Number of patients (%)
Male		25 (78.1)
Right-sided PNFH		20 (62.5)
Medical condition	Crossing legs	14 (43.8)
	Squatting	7 (21.9)
	Prolonged sleep	5 (15.6)
	Weight loss	5 (15.6)
	Both crossing legs and weight loss	6 (18.8)
	Prolonged sleep	5 (15.6)
Neurological examination - weakness	Dorsiflexion of foot	31 (96.9)
	Eversion of foot	26 (81.3)
	None	1 (3.1)
Neurological examination - sensory abnormality	Dorsum of foot	10 (31.3)
	Lateral of leg	1 (3.1)
	Both foot dorsum and leg lateral	15 (46.9)
	None	6 (18.8)

Electrodiagnostic parameter	Mean ± SD (min-max) (number)
Terminal CMAP amplitude (mV) EDB / TA	6.2 ± 2.8 (0–11.9) (n = 32) / 7.5 ± 3.3 (2.1–14.5) (n = 32)
Motor NCV across BFH-PF segment (m/s) EDB^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included. /TA^‡ ‡ Since peroneal nerve CMAP (TA) could not be obtained in one patient by peroneal nerve stimulation at the popliteal fossa, this patient was not included.	36.7 ± 7.5 (22–53) (n = 31) / 39.2 ± 11.7 (20–65) (n = 31)
CMAP amplitude reduction in percentage across BFH-PF segment (%) EDB^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included. / TA	58.7 ± 32.1 (0–98.1) (n = 31) / 53.1 ± 26.6 (0–100) (n = 32)
Motor NCV difference between ankle-BFH and BFH-PF segments EDB (m/s)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	11.1 ± 6.9 (2–27) (n = 31)
Reduction of motor NCV across the BFH-PF segment compared with that across the ankle-below fibular head segment (%)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	23.1 ± 13.8 (4.2–51.1) (n = 31)
Superficial peroneal CNAP amplitude (μV)	12.6 ± 8.4 (0–27.7) (n = 32)
Superficial peroneal sensory NCV (m/s) ^§ § Since superficial peroneal nerve CNAP could not be obtained in three patients, these patients were not included.	48.4 ± 5.8 (37.0–57.5) (n = 28)
The severity of active denervation – TA	2.5 ± 0.8 (1–4)
The severity of active denervation – PL	1.3 ± 0.5 (0–3)

Electrodiagnostic parameters	Number of patients (%)
CMAP amplitude (mV) < 3.7 mV (EDB)	13 (40.6)
CMAP amplitude (mV) < 3.9 mV (TA)	9 (28.1)
Motor NCV across BFH-PF segment < 40.1 m/s (EDB)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	20 (64.5)
Motor NCV across BFH-PF segment < 41.0 m/s (TA)^‡ ‡ Since peroneal nerve CMAP (TA) could not be obtained in one patient by peroneal nerve stimulation at the popliteal fossa, this patient was not included.	19 (61.3)
Motor NCV across BFH-PF segment < 40.1 m/s (EDB) or < 41 m/s (TA)	32 (75.0)
CMAP amplitude reduction in percentage across BFH-PF segment > 25% (EDB)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	24 (77.4)
CMAP amplitude reduction in percentage across BFH-PF segment > 25% (TA)	29 (90.6)
CMAP amplitude reduction in percentage across BFH-PF segment > 25% (EDB or TA)	31 (96.9)
Motor NCV difference between ankle-below fibular head and BFH-PF segments > 6 m/s (EDB)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	20 (64.5)
Reduction of motor NCV across the BFH-PF segment compared with that across the ankle-BFH segment > 12% (EDB)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	22 (71.0)
Superficial peroneal CNAP amplitude < 5.3 μV	8 (25)
Superficial peroneal sensory NCV < 37.0 m/s^§ § Since superficial peroneal nerve CNAP could not be obtained in three patients, these patients were not included.	1 (3.6)
PSW or fibrillation potentials – TA	32 (100)
PSW or fibrillation potentials – PL	23 (71.9)
Neurogenic MUAP – TA	1 (3.1)

Clinical and electrodiagnostic parameter	LANSS score
Clinical and electrodiagnostic parameter	P	R
Age	0.576	0.103
Duration	0.997	0.001
MRC score of DF	0.330	-0.178
MRC score of eversion	0.305	−0.187
Peroneal nerve CMAP amplitude (EDB)	0.203	0.231
Peroneal nerve CMAP amplitude (TA)	0.846	0.036
Motor NCV across BFH-PF segment (EDB)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	0.090	−0.310
Motor NCV across BFH-PF segment (TA)^‡ ‡ Since peroneal nerve CMAP (TA) could not be obtained in one patient by peroneal nerve stimulation at the popliteal fossa, this patient was not included.	0.991	0.002
CMAP amplitude reduction in percentage across BFH-PF segment (EDB)^† † Since peroneal nerve CMAP (EDB) could not be obtained in one patient, this patient was not included.	0.465	0.136
CMAP amplitude reduction in percentage across BFH-PF segment (TA)	0.991	0.002
Superficial peroneal CNAP amplitude	0.621	−0.091
Superficial peroneal sensory NCV^§ § Since superficial peroneal nerve CNAP could not be obtained in three patients, these patients were not included. Spearman's correlation test was used.	0.663	−0.086
The severity of active denervation – TA	0.888	0.026
The severity of active denervation – PL	0.398	0.155

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[1] Address for correspondence Halit Fidancı, (e-mail: dr.halitfidanci@gmail.com).