A Man With a Bent Spine

A 65-year-old man developed a sudden onset of nonradiating, severe back pain, and he had to lie down on the floor for several hours. The next day he felt weak and had difficulty straightening out his back. The pain went away after 3 days, but he continued to have difficulty stretching and standing erect. He walked bent forward, his gait was unsteady, and he used a cane to prevent his trunk from bending. He was very uncomfortable when he walked and became tired after long walks. He also had difficulty raising his arms above his head due to lack of stability.

Past medical history included surgery for back pain in the remote past, inguinal hernia repair, hemorrhoidectomy, kidney stones, and prostatic hypertrophy. He was on a cholesterol-lowering drug but never took antipsychotics. His family history was noncontributory. He did not smoke and drank socially.

Examination revealed normal mentation and cranial nerves. He stood with a forward-bent posture ( Fig. 104-1 ). Muscle strength testing showed mild weakness of the neck flexors but no weakness or atrophy in the upper or lower extremities, except for 4/5 weakness in the hip and thoracic extensors. He was able to rise up from a chair without using his hands and even squatted normally. His back was flattened. Reflexes were 2+ and symmetrical, except for trace at the ankles; no pathologic reflexes were detected. There was no rigidity, tremors, or dystonia. Sensory examination and coordination were normal. Straight leg raising was negative. The rest of the examination was unremarkable.

What is the Differential Diagnosis?

This patient appears to have bent spine syndrome , or camptocormia , from the Greek kamptos (bent forward) and kormos (trunk). This syndrome might be secondary to neurogenic atrophy of the thoracic paraspinal muscles or a primary myopathy. Thus the term isolated trunk extensor myopathy is also used. The possibility of a dystonic process was considered, but there was no evidence of dystonia, as when the patient lay in a lateral position, there was no spontaneous bending of the trunk.

What Tests Should be Done?

Complete blood profile and thyroid studies were normal. Serum creatine kinase was 66.1 IU/L (normal, <200 IU/L). Acetylcholine receptor antibodies, FANA, and erythrocyte sedimentation rate were normal. Bone density studies revealed evidence of mild osteopenia.

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	4.0	11	–
Fibular head	11.6	10	41
Knee	13.5	9	50

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Tibial Nerve R.	Normal ≤ 5.3	Normal ≥ 4	Normal ≥ 40
Ankle	5.2	19	–
Pop. fossa	15.1	17	45

Nerve and Site	Latency (ms)	Amplitude (mV)	Conduction Velocity (m/s)
Ulnar Nerve R.	Normal ≤ 3.7	Normal ≥ 8	Normal ≥ 50
Wrist	3.6	14	–
Below elbow	7.8	13	56
Above elbow	10.1	13	52
Axilla	12.1	12	60

F-Wave and Tibial H-Reflex Studies

Nerve	Latency (ms)	Normal Latency ≤ (ms)
Peroneal nerve R.	52.7	54
Tibial nerve R.	53.4	54
Ulnar nerve R.	29.2	30
H-reflex R.	33.8	34
H-reflex L.	33.2	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	18	11	40	40
Superficial peroneal nerve R.	3.4	3.5	3.9	4.0	10	10	41	40
Ulnar nerve R.	2.8	2.6	3.3	3.1	15	13	43	50
Ulnar nerve L.	2.6	2.6	3.1	3.1	18	13	50	50