A Sedentary Man With Acute Respiratory Failure and Myoglobinuria

A 51-year-old man came with a 4-day history of general malaise, cough, fever, and muscle aches. He had no previous similar episodes.

The patient’s parents were first-degree cousins. He required resuscitation at birth, but other details of the perinatal history were not available. He always had impaired vision and mild bilateral spasticity that was thought to be related to trauma or anoxia at birth. His lifestyle was always sedentary, and he was deferred from military service. He worked as a salesman. Essential hypertension was discovered at age 46 and treated with hydrochlorothiazide and spironolactone (each 25 mg/day). During a routine medical evaluation, his serum creatine kinase (CK) was high at 1200 IU/L (normal, <200 IU/L) without an obvious cause. He had occasional chest pain that was not related to exercise or fasting and did not coincide with rises in serum CK.

There was no family history of neuromuscular disease.

Vital signs were normal except for a temperature of 38°C. His vital capacity was 380 mL. He developed respiratory distress and an endotracheal tube was inserted. He then received respiratory assistance for 11 days.

Visual acuity was limited to counting fingers. His optic disks were atrophic and of small diameter with a paucity of vessels. There was weakness of the left lateral rectus and bilateral nystagmus on horizontal gaze. Muscle tests showed mild proximal weakness and spasticity with hyperreflexia in the legs, but there were no Babinski signs. The rest of the examination was unremarkable.

The following laboratory data on admission were normal: complete blood cell and differential count, sedimentation rate, blood urea nitrogen (BUN), calcium, bilirubin, alkaline phosphatase, cholesterol, uric acid, protein electrophoresis, and thyroid function studies. Serum creatinine was 1 mg/dL; sodium, 127 mEq/L; potassium, 2.9 mEq/L; chloride, 96 mEq/dL; and CO ₂ , 28 mEq/L.

Serum CK was 36,000 IU/L (normal, 60–210 IU/L); alanine transaminase, 942 IU/L (normal, 9–42 IU/L); lactate dehydrogenase, 912 IU/L (normal, 50–200 IU/L); and aldolase, 92 IU/L (normal, 0–6 IU/L). His urine was dark brown with a specific gravity of 1.018, pH 6, 0–5 red cells per high-power field, and a few white cells. The protein reaction was 3+, and tests for glucose, ketones, and bilirubin were negative. Radial immunodiffusion was positive for myoglobin. Acute and convalescent complement fixation titers for coxsackie, influenza, and parainfluenza viruses were normal. Blood and sputum cultures were negative. Electrocardiogram was normal. Chest radiograms were normal except for a mild left ventricular hypertrophy. A CT scan of the head showed mild cerebral atrophy.

Despite proper therapy for myoglobinuria, on the 10th day of his hospital stay his BUN had increased to 100 μg/dL and creatinine to 6.5 μg/dL, but his urinary output continued to be more than 1200 mg/day, indicating high-output renal failure. This was treated by hemodialysis. He improved slowly and was removed from the ventilator; his respiratory function and his renal function gradually returned to normal.

An EMG Test was Performed

Motor Nerve Studies

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Peroneal Nerve R.	Normal ≤ 5.7	Normal ≥ 3	Normal ≥ 40
Ankle	5.2	3	–
Fibular head	12.0	3	40
Knee	14.0	3	45

Ulnar Nerve R.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	3.6	9	–
Below elbow	7.3	8	55
Above elbow	9.4	8	57

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Peroneal nerve R.	52.6	54
Ulnar nerve R.	28.5	30
H-reflex R.	34.0	34
H-reflex L.	33.6	34

Sensory Nerve Studies

Nerve	Onset Latency (ms)	Normal Onset Latency ≤ (ms)	Peak Latency (ms)	Normal Peak Latency ≤ (ms)	Amp (μV)	Normal Amp ≥ (μV)	Conduction Velocity (m/s)	Normal Conduction Velocity ≥ (m/s)
Sural nerve R.	3.4	3.5	3.9	4.0	12	11	41	40
Ulnar nerve R.	2.2	2.6	2.7	3.1	15	13	55	50

EMG Data

CRD = complex repetitive discharges

Muscle	Insrt Activity	Fibs	Pos Waves	Fasc	Amp	Dur	Poly	Pattern
Pectoralis major R.	CRD	None	None	None	Norm	Norm	Many	Full
Deltoid R.	Norm	None	None	None	Norm	Norm	None	Full
Biceps brachii R.	Norm	None	None	None	Norm	Norm	None	Full
First dorsal interosseous R.	Norm	None	None	None	Norm	Norm	None	Full
Iliopsoas R.	Norm	None	None	None	Norm	Norm	None	Full
Vastus lateralis R.	Norm	None	None	None	Norm	Norm	None	Full
Gastrocnemius R.	Norm	None	None	None	Norm	Norm	None	Full