Case Vignettes in Neurology

PATIENT CASE STUDIES

Case 34. (Pediatric Neurology Case 4.)
Case discussion History: A 14 year old boy is evaluated for nonprogressive muscular weakness and decreased muscle mass. His past history is significant for hypotonia in the newborn period and delayed acquisition of gross motor milestones. He did not sit until 12 months of age, and he did not walk until 28 months of age. His language and social development were normal and he has done average work in school. Exam: The patient is thin with obvious decreased muscle bulk. His face lacks expression and there is winging of the scapulae. Muscle strength and reflexes are reduced in all four extremities. His gait is awkward.
Summarize the Case in 1-2 sentences. 14 year-old male presents with nonprogressive diffuse muscle weakness that is reported as evident since birth (as delayed motor developmental milestones and infantile hypotonia). With this time course as well as his present presentation of bilateral, upper and lower weakness with decreased muscle mass, hyporeflexia, winged scapulae, lack of facial expressions, and normal social and academic progress, the case is suggestive of congenital myopathy. the summary should not be the diagnosis; rather the summary should be a summary of the key clinical features, time intensity course, physical signs, age, sex, relevant pmh, fh. Discuss lesion localization on the basis of the physical examination. He has a motor unit disorder, which means either the PNS or muscle is abnormal. We deduced this from his hyporeflexia, muscle weakness, and muscle atrophy. We can rule out a CNS disorder because of the hyporeflexia and decreased muscle mass. (However, it should be noted that hypotonia in infants and young children can be due to a CNS, PNS, neuromuscular junction, muscle, or systemic problem.) good; you left out the NMJ as a possible site, note reflexes are reduced not lost suggesting a muscle disorder or a nmj disorder Discuss underlying pathogenesis on the basis of clinical course. Chronic, nonprogressive, with gross motor development delay, suggesting congenital cause. congenital is suggested by the presence of difficulties in the neonatal period Indicate one likely clinical diagnosis. List (or classify) alternative diagnoses. Our tentative diagnosis is centronuclear myopathy. Alternative diagnoses are Facioscapulohumeral dystrophy (FSHD), other metabolic or mitochondrial myopathies, and Spinal Muscular Atrophy. why centronuclear myopathy; what other congenital myopathies are there? Indicate 2 ancillary tests that would assist in confirming or refuting the clinical diagnosis. Indicate the test results that would confirm the clinical diagnosis. EMG (including nerve conduction study) will show: - positive sharp waves - fibrillation potential - complex and competitive discharges - possibly myotonic discharges (rare) Muscle biopsy: will show rows of central nuclei, often surrounded by a halo, in hypertrophic muscle fibers. emg findings are incorrect; why do you expect to find psws, fibs, discharges and myotonia with centronuclear myopathy? Indicate complications of the disease and ancillary tests that would help evaluate them. Centronuclear myopathy can lead to respiratory failure (if muscle weakness progresses), loss of physical mobility, and scoliosis. ok Discuss how the underlying pathophysiology is relevant in the management of this patient. The biochemical process causing weakness in centronuclear myopathy is unknown, but thought to involve altered cytoskeletal networks of dystrophin, desmin, and tubulin. The gene for the neonatal form has been localized to Xq28 (X-linked recessive), permitting identification of carriers and prenatal diagnosis. Treatment revolves around the symptoms that are present, although there is hope for a future gene therapy, since it is a genetic based disorder. This patient would benefit from supportive ambulatory aids and possible orthotic devices to improve his mobility. ok; what is the function of dystrophin, desmin, tubulin?

Case 34. (Pediatric Neurology Case 4.)

Case discussion

History: A 14 year old boy is evaluated for nonprogressive muscular weakness and decreased muscle mass. His past history is significant for hypotonia in the newborn period and delayed acquisition of gross motor milestones. He did not sit until 12 months of age, and he did not walk until 28 months of age. His language and social development were normal and he has done average work in school.

Exam: The patient is thin with obvious decreased muscle bulk. His face lacks expression and there is winging of the scapulae. Muscle strength and reflexes are reduced in all four extremities. His gait is awkward.

Summarize the Case in 1-2 sentences.

14 year-old male presents with nonprogressive diffuse muscle weakness that is reported as evident since birth (as delayed motor developmental milestones and infantile hypotonia). With this time course as well as his present presentation of bilateral, upper and lower weakness with decreased muscle mass, hyporeflexia, winged scapulae, lack of facial expressions, and normal social and academic progress, the case is suggestive of congenital myopathy.

the summary should not be the diagnosis; rather the summary should be a summary of the key clinical features, time intensity course, physical signs, age, sex, relevant pmh, fh.

Discuss lesion localization on the basis of the physical examination.

He has a motor unit disorder, which means either the PNS or muscle is abnormal. We deduced this from his hyporeflexia, muscle weakness, and muscle atrophy. We can rule out a CNS disorder because of the hyporeflexia and decreased muscle mass. (However, it should be noted that hypotonia in infants and young children can be due to a CNS, PNS, neuromuscular junction, muscle, or systemic problem.)

good; you left out the NMJ as a possible site, note reflexes are reduced not lost suggesting a muscle disorder or a nmj disorder

Discuss underlying pathogenesis on the basis of clinical course.

Chronic, nonprogressive, with gross motor development delay, suggesting congenital cause.

congenital is suggested by the presence of difficulties in the neonatal period

Indicate one likely clinical diagnosis. List (or classify) alternative diagnoses.

Our tentative diagnosis is centronuclear myopathy.
Alternative diagnoses are Facioscapulohumeral dystrophy (FSHD), other metabolic or mitochondrial myopathies, and Spinal Muscular Atrophy.

why centronuclear myopathy; what other congenital myopathies are there?

Indicate 2 ancillary tests that would assist in confirming or refuting the clinical diagnosis. Indicate the test results that would confirm the clinical diagnosis.

EMG (including nerve conduction study) will show:
- positive sharp waves
- fibrillation potential
- complex and competitive discharges
- possibly myotonic discharges (rare)

Muscle biopsy: will show rows of central nuclei, often surrounded by a halo, in hypertrophic muscle fibers.

emg findings are incorrect; why do you expect to find psws, fibs, discharges and myotonia with centronuclear myopathy?

Indicate complications of the disease and ancillary tests that would help evaluate them.

Centronuclear myopathy can lead to respiratory failure (if muscle weakness progresses), loss of physical mobility, and scoliosis.

Discuss how the underlying pathophysiology is relevant in the management of this patient.

The biochemical process causing weakness in centronuclear myopathy is unknown, but thought to involve altered cytoskeletal networks of dystrophin, desmin, and tubulin. The gene for the neonatal form has been localized to Xq28 (X-linked recessive), permitting identification of carriers and prenatal diagnosis. Treatment revolves around the symptoms that are present, although there is hope for a future gene therapy, since it is a genetic based disorder. This patient would benefit from supportive ambulatory aids and possible orthotic devices to improve his mobility.

ok; what is the function of dystrophin, desmin, tubulin?