00:01 So let's start with a case. 00:03 A 6-year-old boy who presents with weakness. 00:06 This 6-year-old boy presents for new evaluation of weakness and difficulty walking. 00:11 The boy was born at 37 weeks by uncomplicated vaginal delivery. 00:15 He met all milestones well until about 3 years ago or 3 years of age, when he first started having difficulties with walking, particularly running longer distances, where he would get tired and weak. 00:29 Over the past several years, he has had progressive weakness with difficulty running, jumping and climbing. 00:35 He has no other medical conditions. 00:37 He's an only child and his mother is 42 years old, and has had an abnormal gait with arched back but no other signs of weakness. 00:46 And she does see a cardiologist for an unspecified heart rhythm abnormality. 00:53 Over the last 6 months, the boy's weakness has continued to worsen. 00:57 He now has difficulty standing up from a lying position. 01:00 His calf muscles are enlarged and hypertrophied bilaterally and symmetrically. 01:05 He has no problems breathing. 01:07 A neurologic examination shows proximal weakness in the arms and legs. 01:11 Cranial nerves, sensory examination, reflex exam and cerebellar exam are all normal. 01:18 Workup shows a markedly increased creatine kinase over 40,000 IU/mL. 01:25 So what's the most likely diagnosis? Well, let's go back and look through some of the key details of this case. 01:32 First, we see that this is a young child, which is tipping us off that this may be an inherited muscle disorder. 01:39 And the patient presents with progressive weakness, which is really important when we differentiate the muscular dystrophies from other inherited causes of muscle disorders. 01:49 On the second part of the case, we see a number of key findings. 01:53 First is the distribution. 01:55 This is proximal weakness, proximal in the legs and proximal in the arms. 01:59 And that really puts us into the bucket the category of proximal predominant muscular dystrophies. 02:06 What are the sensory findings? Well, here we see the sensory exam is normal. 02:10 The reflex exam is also normal. 02:12 And then there's a fourth important wildcard and that is calf muscle enlargement or hypertrophy or pseudohypertrophy, which will point us in the direction of a muscular dystrophy, that and we see this really elevated creatine kinase, which points us to some type of inflammation in and around the muscle. 02:31 So what's the most likely diagnosis? Polymyositis, Duchenne's muscular dystrophy, Limb-girdle muscular dystrophy or Dermatomyositis? Well, polymyositis is an acquired cause of muscle disorder and this patient presents with an age, a sex and a distribution of weakness that is not consistent, inconsistent with polymyositis. 02:54 Dermatomyositis presents with a rash in addition to acquired proximal muscle weakness, which is inconsistent with this case. 03:02 Limb-girdle muscular dystrophy can be seen as a cause of muscular dystrophy but this patient's age and sex really points us to Duchenne's muscular dystrophy.
The lecture Case: 6-year-old Boy with Weakness by Roy Strowd, MD is from the course Hereditary Neuromuscular Disorders.
Besides the distribution of weakness and the results of a sensory examination, what other part of the physical examination is important when investigating a patient with muscle weakness?
One major difference between Duchenne’s muscular dystrophy (DMD) and polymyositis is that DMD…?
5 Stars |
|
5 |
4 Stars |
|
0 |
3 Stars |
|
0 |
2 Stars |
|
0 |
1 Star |
|
0 |