The patient was an elderly man lying comfortably in bed. He was of average height and weight.
On examination of his upper limbs there were no abnormalities of size and shape of the limbs and the skin was normal. This excluded a neurological deficit dating back to childhood, (normal size and shape) and significant sensory deficit as there were no skin changes.
No wasting was apparent on routine inspection of the upper limbs and there were no involuntary movements.
Tone was normal at the wrist and the elbow but tone was flaccid at the shoulder. When the patient's arms were raised above the head and let go they fell away without any control. This showed that he had flaccidity at the shoulder and this raised the possibility of either a myopathy or lower motor neurone lesion at the shoulder (see ACES for PACES page 449)
The trainee examined power beginning at the shoulders and working distally and demonstrated weakness of abduction and adduction at the shoulder.
He was asked to re-examine power in the upper limbs beginning distally (starting with the small muscles of the hands) and working proximally (to the shoulders and the muscles around the scapula). This time he noticed that there was wasting of the muscles around the scapula and there was weakness of abduction and adduction at the shoulder and weakness of the muscles around the scapula. This suggested either a myopathy or a lower motor neurone lesion affecting C4, C5.
On examination of his reflexes the biceps jerk and triceps jerk were exaggerated there was an inverted supinator jerk and Hoffman's sign was positive. This indicated a lower motor neurone lesion at C5 with upper motor neurone lesion below that level (see ACES for PACES page 508). This together with the signs found earlier would indicate that he had a lower motor neurone lesion affecting C4, C5 with an upper motor neurone lesion below that level. This would fit in with a cervical myelopathy.
Coordination was poor but this reflected the proximal weakness rather than a cerebellar lesion
On examination of the sensory system there was loss of sensation over C4, C5 on the right hand side and equivocal loss of sensation over C4, C5 on the left hand side
Diagnosis
Cervical myelopathy affecting C4, C5 nerve roots
Learning points
This case was difficult for the trainees. The main reason for missing the diagnosis, in the first instance, was that there was a failure to follow the correct method.
Not examining tone at the shoulder was a crucial mistake. This would have shown evidence of flaccid weakness affecting C5
Examining power by beginning proximally was the most crucial error. The scapular region was not examined and this meant that the wasting and weakness around the scapula was missed and thereby crucial evidence was missed.
The trainee had not seen an inverted supinator jerk before but this is an important sign to look for when performing the tendon reflexes. An additional problem was that the Hoffman reflex was not elicited correctly and hence the positive reflex was missed. Practice performing the Hoffman reflex using the correct method (ACES for PACES page 414)
By the time the reflexes were examined the diagnosis was clear and sensory examination only added further evidence to confirm the earlier suspicions.
Remember the secret of success in neurology is following correct method and analysing at each step. Read up the section on examination of the CNS in chapter 16 of ACES for PACES and practice repeatedly.
Revision Tips
Revise the nerve supply of the skin, the muscles and the reflexes ACES for PACES pages 426-428
