310 - Late Onset Adult Diagnosed Limb Girdle Muscular Dystrophy with superimposed Chemotherapy Induced Peripheral Neuropathy by Electrodiagnostic tudies

Case Diagnosis: Limb Girdle Muscular Dystrophy with Chemotherapy-Induced Peripheral Neuropathy

Case Description: A 75-year-old female with a past medical history of breast cancer status post chemotherapy and radiation (2013) presented with gradual bilateral lower extremity weakness and Trendelenburg gait for 30+ years. She was previously diagnosed with chemotherapy-induced peripheral neuropathy ten years ago.

The patient demonstrated a waddling gait and hyperlordosis. Physical examination was noteworthy for weakness with bilateral shoulder abduction, hip flexion, and ankle dorsiflexion (4/5 strength). Vibratory sensation disrupted in a length-dependent pattern with absent reflexes.

CK levels were obtained and elevated. Electrodiagnostic nerve conduction studies showed absent Right sural and peroneal motor nerve recordings. Tibial motor response showed low amplitude, prolonged latency, and normal velocity. Needle EMG findings of the anterior and posterior tibialis and vastus medialis demonstrated increased insertional activity. Sustained p-waves and fibrillations were noted in the anterior tibialis. The iliopsoas, gluteus medius and infraspinatus showed early recruitment with short, polyphasic voluntary motor unit action potentials (MAUPs).

Discussions: The electrodiagnostic evidence shows proximal myopathy, sensorimotor axonal neuropathy, distal active denervation, and chronic reinnervation. LGMD is a genetic disorder that can affect the protein involved with muscle function, regulation, and repair. Progressive proximal muscular weakness and ambulation are primordially affected. Providing suitable assisted devices is essential as weakness progresses. Elevated creatinine kinase is found in these patients with myopathic changes on EMG. This patient also acquired peripheral neuropathy due to prior chemotherapeutic agents. These findings are typically not seen with myopathies. Electrodiagnostic studies helped confirm the diagnosis and the extent of the peripheral neuropathy.

Conclusions: Myopathy and neuropathies can present comparable findings, such as weakness. To avoid delay in diagnosis, patients with suspected LMGD should undergo a thorough physical exam, CK-level testing, and electrodiagnostic studies. For optimal functional improvement, assistive equipment and therapies should address both issues.