Objective:

N/A

Background:

Dropped head syndrome (DHS) is the result of neck extensor muscle weakness and has a broad differential diagnosis, including both neuromuscular and non-neuromuscular causes. The common neuromuscular differential diagnoses for isolated head drop include amyotrophic lateral sclerosis, myasthenia gravis, and isolated neck extensor myopathy.  This case reports a rare presentation of a mitochondrial disorder as a cause of DHS.

Design/Methods:

Case Presentation: A 77-year-old female with restless leg syndrome, , hyperlipidemia, and lumbar degenerative disc disease presented with progressive neck weakness, head tilting, and over two to three years. Family history was non-contributory. Physical examination revealed a forward-bent neck tilted laterally and anteriorly to the right shoulder. The cranial nerve examination was normal. Neck flexion strength was normal (MRC grade 5), while neck extension was weak (MRC grade 3+). Muscle strength and tone were normal in limb muscles, without atrophy or fasciculations. Serum CK, aldolase, and myasthenia gravis panel were normal. Cervical MRI revealed a broad-based posterior disc osteophyte complex without myelopathy or significant spinal canal or neural foraminal stenosis. Electrodiagnostic evaluation revealed a myopathic process with abnormal spontaneous activity only in the left C7 paraspinal muscle.  Soft tissue MRI of neck showed bilateral atrophy of the erector spinae musculature with fatty infiltration. Muscle biopsy was consistent with myopathy with ragged red fibers corresponding to a mitochondrial disorder. Genetic testing results are pending

Results:

N/A

Conclusions:

Mitochondrial myopathies are a heterogeneous group of disorders characterized by impaired mitochondrial function, leading to various clinical manifestations and diagnostic challenges. The differentiation of this condition from isolated neck extensor myopathy is essential, as further work-up is needed to rule out the involvement of other organs and to provide appropriate surveillance for patients with mitochondrial myopathy. Muscle biopsy is key in patients without a full clinical picture and positive family history.