7 June Neurology

Question 1

Describe Guillain-Barre syndrome

Answer 1

Autoimmune demyelination of peripheral nerves
Starts peripherally in hands and feet with parasthesias that progress to muscle weakness and work centrally to the trunk
Often preceded by gastroenteritis or other infection with Campylobacter or CMV
Dx: MRI to rule out other causes of muscle weakness, LP showing elevated protein and low wbc, commonly absent reflexes and nerve conduction studies
Tx: supportive including intubation if needed, IVIG or plasmaphoresis to remove antibodies

Question 2

Describe Lambert-Eaton syndrome and how it compares with myasthenia gravis

Answer 2

Central weakness caused by antibodies against presynaptic Ca channels leading to weakness that is overcome by repeated stimulation or through exercise
Considered a paraneoplastic syndrome as it is associated with small cell lung cancer and is often the first presenting sign
More common in individuals over 40, but can happen at any age
Different from MG in that it improves with muscle use, involves the legs most commonly, rarely involves the eyes

Question 3

Describe Myasthenia Gravis and relation to Lambert-Eaton syndrome

Answer 3

Antibodies against postsynaptic Ach receptors leading to weakness that worsens with use
Associated with thymoma and removal can improve symptoms in some cases
Commonly affects the eyes leading to ptosis, ophthalmoplegia, and affects ability to swallow and affects the muscles of the face
Different from LE in that affects the eyes and worsens with muscle use and improves with rest

Question 4

Child presents with loss of motor milestones in first 6 months of life. What two conditions should come to mind? What are their common and differing features?

Answer 4

Niemann-Pick disease and Tay-Sachs
Common features: loss of motor milestones, hypotonia, feeding difficulties, cherry red macula, AR inheritance

NPD: hepatosplenomegaly, areflexia or hyporeflexia, sphingomyelinase deficiency
Tay-Sachs: hyperreflexia, beta-hexosaminidase A deficiency

Question 5

Describe PKU disease

Answer 5

AR deficiency in phenylalanine hydroxylase leading to increased levels of phenylalanine which is neurotoxic leading to intellectual disability, seizures, fair complexion from low pigmentation, eczema, and a musty body and urine odor
Screened for in all 50 states because it is very treatable by diet modification avoiding phenylalanine rich foods