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Table 1 Neurophysiological characteristics of a typical patient with asymmetrical SNAPs (Patient 1) and of a patient with completely absent SNAPs (Patient 2) from these series

From: Cerebellar ataxia with sensory ganglionopathy; does autoimmunity have a role to play?

Subject

NCS

Parameter

Median

CMAP

Ulnar (ADM)

CMAP

Tibial

CMAP

Median

SNAP

Ulnar

SNAP

Radial

SNAP

Sural

SNAP

Superficial Peroneal

SNAP

 

Side

(R)

(R)

(R)

(R)

(L)

(R)

(L)

(R)

(L)

(R)

(L)

(R)

(L)

Patient 1

(Asymmetric SNAPs)

46Y, Female

Amplitude

14.1 mV

10.7 mV

9.2 mV

17.4 μV

6.1 μV

3.1 μV

5.7 μV

18.4 μV

12.4 μV

21.5 μV

12.8 μV

7.7 μV

3.4. μV

Conduction velocity

60 m/s

(Elbow-Wrist)

60 m/s

(Below elbow – Wrist)

70 m/s

(Above elbow – below elbow)

NC

56 m/s

(Digit III –Wrist)

60 m/s

(Digit III –Wrist)

58 m/s

(Digit V –Wrist)

57 m/s

(Digit V–Wrist)

58 m/s

(Forearm- Snuff Box

55 m/s

Forearm- Snuff Box

48 m/s

Calf – lateral malleolus

48 m/s

Calf – lateral malleolus

48 m/s

Leg – Dorsum of the foot

47 m/s

Leg – Dorsum of the foot

Patient 2

(Absent SNAPS)

67Y, Male

Amplitude

8.3 mV

6.3 mV

3.0 mV

NR

NR

NR

NR

NR

NR

NR

NR

NR

NR

Conduction velocity

54 m/s

(Elbow-Wrist)

48 m/s

(Below elbow – Wrist)

59 m/s

(Above elbow – below elbow)

NC

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

  1. NCS nerve conduction studies, CMAP compound muscle action potential, SNAP sensory nerve action potential, ADM abductor digiti minimi, R right, L left, NC not checked, NR not recordable, NA not applicable