An Elderly Woman With a Progressive Neuropathy

A 75-year-old woman with congestive heart failure and coronary artery disease was evaluated for progressive numbness and weakness in the feet and legs for the past 3 months. She had been on lanoxin, furosemide, and amiodarone. Past medical and family histories were unremarkable, and she did not smoke or drink. Gait was normal; the rest of the neurologic examination was unremarkable.

Examination revealed normal mentation and gross cognitive function. Cranial nerves were normal. There was 4–4+/5 weakness in all extremities; the iliopsoas and glutei were 3–4−/5 bilaterally; quadriceps, adductors, and hamstrings were 5−/5; foot dorsiflexors 4/5; evertors 4/5; flexors 5−/5. There was decreased pinprick in a stocking distribution up to the midarm and midcalf. She was areflexic, and her toes were downgoing.

What is the Differential Diagnosis?

This woman presented with progressive motor and sensory neuropathy. There was no history of diabetes or renal disease, but she had congestive heart failure and a negative family history.

Other conditions such as connective tissue disorder, an autoimmune polyneuropathy, a toxic neuropathy, or a neuropathy associated with carcinoma needed to be considered. The congestive heart failure could also suggest amyloidosis.

The patient was on amiodarone which could cause a peripheral neuropathy.

What Should Be Done?

A complete metabolic panel was normal except for mildly elevated sugar of 182 mg/dL (normal, <110 mg/dL). Erythrocyte sedimentation rate was 52 mm/h (normal, <30 mm/h) and when repeated was 39 mm/h. Fluorescent antinuclear antibody was positive 1:80. C3 and C4 complement and extractable nuclear antibody titers were normal.

An EMG Test was Performed

Motor Nerve Studies

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Peroneal Nerve L.	Normal ≤ 5.7	Normal ≥ 4	Normal ≥ 40
Ankle	4.6	2	–
Fibular head	10.9	2	37
Knee	12.4	2	39

Motor Nerve Studies—cont’d

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Tibial Nerve L.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	4.4	3	–
Pop. fossa	12.6	2	37

Median Nerve L.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	2.7	7	–
Elbow	6.3	7	49

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Peroneal nerve L.	51.5	54
Tibial nerve L.	52.8	54
Median nerve L.	28.9	30
H-reflex L.	NR	34
H-reflex R.	NR	34

Sensory Nerve Studies

Nerve	Peak Latency (ms)	Normal Peak Latency ≤ (ms)	Amp (μV)	Normal Amp ≥ (μV)
Sural nerve L.	NR	4.0	NR	11
Superficial peroneal nerve L.	NR	4.0	NR	8–10
Median nerve L.	NR	3.1	NR	13

EMG Data

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Vastus lateralis L.	Norm	None	None	None	Norm	Norm	None	Full
Tibialis anterior L.	Norm	None	None	None	Lg	Inc	None	Red
Peroneus longus L.	Inc	None	None	None	Norm	Norm	None	Full
Gastrocnemius L.	Inc	None	1+	None	Lg	Inc	None	Red
Vastus lateralis R.	Norm	None	None	None	Lg	Inc	None	Red
Tibialis anterior R.	Inc	None	None	None	Lg	Inc	None	Red
Gastrocnemius R.	Inc	None	1+	None	Norm	Norm	None	Full
First dorsal interosseous L.	Norm	None	None	None	Lg	Inc	None	Red
Flexor carpi ulnaris L.	Norm	None	None	None	Norm	Norm	None	Full