An atypical case of an 11-year old boy diagnosed with Charcot-Marie-Tooth disease type 4C (CMT4C) associated with dropped head syndrome, a medical condition caused by severe spine deformities coupled with neck muscle weakness, was described in a recent study.
The case report, “Dropped head syndrome as a manifestation of Charcot-Marie-Tooth disease type 4C,” was published in the journal Neuromuscular Disorders.
Charcot-Marie-Tooth disease (CMT) includes a series of inherited diseases that affect the peripheral nervous system — the network of nerves responsible for movement and sensation in the arms and legs.
CMT4C is an early-onset form of the disease and also one of the most common worldwide. It is characterized by severe spine and feet deformities and limb muscle weakness.
In this case report, researchers from the Universidade Federal do Rio Grande do Sul in Brazil described a boy with a confirmed diagnosis of CMT4C associated with dropped head syndrome and proximal (closest to the body’s midline) limb muscle weakness, two medical features that are not included in the spectrum of classic CMT4C symptoms.
The boy, born to first-degree cousins, started experiencing the first symptoms of the disease by the age of 3, when he started falling frequently.
Soon after, by 4 years old, spine scoliosis became apparent, and the parents noticed their son was struggling with muscle weakness in the arms and legs. By the age of 6, the boy required walking aids, and by 9, he was wheelchair-bound.
The boy’s first neurological evaluation at 9 years old revealed substantial proximal limb and facial muscle weakness, dropped head syndrome, dysphagia (difficulty swallowing), and spine and feet deformities. Nerve conduction studies indicated severe abnormalities in nerve signal propagation in the arms and legs, “compatible with a sensorimotor demyelinating polyneuropathy,” according to the researchers.
Gene sequencing studies performed afterward showed the boy carried a missense mutation in the SH3TC2 gene, confirming CMT4C diagnosis. This type of mutation is a single nucleotide mutation that alters protein composition.
At the age of 12, the boy was admitted to the intensive care unit with respiratory failure caused by bronchopneumonia. Although his symptoms improved over the course of the next days and he was discharged from intensive care, his condition rapidly deteriorated after that, and he passed away from acute respiratory failure.
“The present report adds dropped head as a CMT4C disease feature and raises the importance of considering early-onset inherited polyneuropathies in the differential diagnosis of patients with proximal muscle wasting associated with dropped head syndrome,” the researchers wrote.
“Furthermore, it highlights the possibility of acute respiratory failure in these patients even with normal respiratory function tests,” they added.