A Man With Acute Muscle Weakness and Respiratory Failure

A 28-year-old man entered the hospital because of leg weakness which had developed 1 week following some flu-like symptoms. He had been almost unable to walk for 2 days. He became progressively short of breath and had to be intubated in the emergency room because of severe respiratory insufficiency.

Past medical history was unremarkable. He did not smoke or drink.

On examination he was alert and followed commands well while on respiratory assistance; his vital capacity was about 800 mL. Pupils, disks, and extraocular movements were normal. There was a mild bilateral facial weakness but no ptosis, and he had abundant oral secretions. He could not raise his arms above the head or his left leg off the bed. He had weakness of 3−/5 in proximal and distal muscles of the arm and 2+/5 in proximal and distal muscles of the legs. He was areflexic. There was diminished vibration sense in his toes, but pinprick and position senses were normal. There were no Babinski signs.

A complete blood count, serum creatine kinase (CK), and metabolic panel were normal.

Spinal fluid showed normal opening pressure. Protein was 85 mg/dL (normal, <45 mg/dL). There were 120 cells, 80% lymphocytes. Cytology was negative. Glucose was 58 mg/dL (normal, >50 mg/dL). Serum protein electrophoresis was normal.

What is the Differential Diagnosis?

The differential diagnosis of any patient who presents with acute progressive quadriparesis should always include a myelopathy, particularly at a high cervical level. The lack of sensory levels and Babinski signs are against this possibility. Other possibilities include periodic paralysis and disorders of neuromuscular transmission; myositis or rhabdomyolysis are unlikely because of the areflexia, normal serum CK and spinal fluid findings ( Fig. 40-1 ).

The presentation was typical of acute inflammatory demyelinating polyneuropathy (AIDP), or Guillain–Barré syndrome (GBS). Other neuropathies, such as porphyria or arsenic poisoning, are less likely because of the facial weakness and the spinal fluid findings. His acute polyneuropathy with increased cells in the spinal fluid suggests HIV-associated AIDP. Other causes of increased cells in the spinal fluid should be considered, such as Lyme disease and a polio-like paralysis caused by the West Nile virus; however, the patient was not febrile.

What Tests Should Be Done?

His blood chemistry profile was normal. A urine test for porphyrins was negative. Arsenic levels were not elevated. Thyroid profile was normal. HIV tests were positive; rapid plasma regain was negative. Hepatitis serology was negative. Lyme and West Nile titers were not tested.

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	7.1	8	–
Fibular head	14.8	5	36
Knee	17.3	5	34

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Tibial Nerve L.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	6.4	7	–
Knee	16.5	4	38

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Median Nerve R.	Normal ≤ 4.2	Normal ≥ 6	Normal ≥ 50
Wrist	4.9	9	–
Elbow	11.1	7	44

Ulnar Nerve R.	Normal ≤ 3.6	Normal ≥ 8	Normal ≥ 50
Wrist	4.4	12	–
Below elbow	10.4	9	42
Above elbow	14.2	9	41

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)	Persistence (%)
Peroneal nerve R.	77.5	54	20
Tibial nerve L.	68.2	54	60
Median nerve R.	45.5	30	20
Ulnar nerve R.	47.6	30	40
H-reflex R.	NR	34	–
H-reflex L.	NR	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.	3.5	3.5	4.0	4.0	5	11	40	40
Superficial peroneal R.	NR	4.0	NR	4.0	NR	8–10	NR	40
Median nerve R.	2.8	2.6	3.3	3.1	13	20	46	50
Ulnar nerve R.	2.6	2.6	3.1	3.1	6	13	50	50