# Clinical Cases: Motor Systems ## Case 1: Amyotrophic Lateral Sclerosis (ALS) ### Patient Presentation **Demographics:** 62-year-old male **Chief Complaint:** Progressive weakness in right hand and arm for 6 months **History of Present Illness:** A 62-year-old right-handed man presents with gradually worsening weakness that began in his right hand. He first noticed difficulty turning keys and buttoning shirts. Over the past 3 months, weakness has spread to his right arm and he has developed cramping and twitching throughout both arms. He has also noticed difficulty speaking clearly, with occasional slurring, and his wife reports he has been choking on liquids. He denies numbness, tingling, visual changes, or cognitive difficulties. He has lost 15 pounds due to difficulty eating. **Physical Examination:** - Vital signs: Normal - General: Thin male with visible muscle twitching in upper extremities - Neurological: - Mental status: Alert, oriented, cognition intact - Speech: Mildly dysarthric with spastic quality - Cranial nerves: Tongue atrophy with fasciculations; brisk jaw jerk; reduced palate elevation - Motor: - Upper extremities: Atrophy of intrinsic hand muscles bilaterally, worse on right; fasciculations visible in deltoids, biceps, and forearms; strength 3/5 right hand, 4/5 left hand, 4/5 bilateral proximal arms - Lower extremities: Mild weakness hip flexors bilaterally (4+/5); no atrophy yet - Tone: Spasticity in all extremities - Reflexes: 3+ throughout; bilateral Hoffman signs; bilateral upgoing Babinski responses - Sensory: Completely intact to all modalities - Coordination: Intact but limited by weakness **Workup:** - **EMG/Nerve conduction studies:** Widespread acute and chronic denervation in cervical, thoracic, and lumbosacral segments; normal sensory nerve action potentials; fasciculation potentials in multiple muscles - **MRI brain and cervical spine:** Normal (excludes structural lesions) - **Laboratory studies:** Normal (creatine kinase mildly elevated; normal B12, thyroid, paraneoplastic panel) - **Pulmonary function tests:** FVC 72% predicted; early restrictive pattern **Diagnosis:** Amyotrophic lateral sclerosis (ALS) - clinically definite **Treatment:** - Riluzole 50 mg twice daily (glutamate antagonist; modest survival benefit) - Edaravone IV infusions (antioxidant; slows functional decline) - Speech therapy for dysarthria and dysphagia evaluation - Modified diet and eventual discussion of PEG tube placement - Pulmonary follow-up with serial PFTs; noninvasive ventilation when indicated - Physical and occupational therapy - Multidisciplinary ALS clinic enrollment - Palliative care and advance directive discussions **Clinical Pearl:** ALS is defined by the combination of upper motor neuron (UMN) and lower motor neuron (LMN) signs in the same body region. UMN signs include spasticity, hyperreflexia, and Babinski signs; LMN signs include weakness, atrophy, and fasciculations. The coexistence of these apparently contradictory findings (spastic atrophic weakness) is the clinical hallmark. Sensory function is preserved, distinguishing ALS from conditions affecting the entire spinal cord. The El Escorial criteria require UMN and LMN signs in multiple regions (bulbar, cervical, thoracic, lumbosacral) for definite diagnosis. --- ## Case 2: Guillain-Barre Syndrome ### Patient Presentation **Demographics:** 35-year-old female **Chief Complaint:** Progressive weakness and tingling in legs for 4 days **History of Present Illness:** A 35-year-old woman presents with ascending weakness that began with tingling in her feet 5 days ago, following an episode of gastroenteritis 2 weeks prior. The weakness started in her legs and has now progressed to involve her arms. She has difficulty climbing stairs and rising from a chair. Today she noticed weakness in her hands and numbness around her mouth. She denies neck stiffness, fever, or urinary symptoms. **Physical Examination:** - Vital signs: BP 145/92, HR 105, RR 18, negative inspiratory force (NIF) -35 cmH2O (concerning) - General: Anxious, speaking in short sentences - Neurological: - Mental status: Alert, oriented - Cranial nerves: Bifacial weakness; intact eye movements; weak palate elevation - Motor: Symmetric weakness: 3/5 hip flexors, 4/5 knee extension, 2/5 ankle dorsiflexion; 4/5 shoulder abduction, 3/5 grip strength - Tone: Flaccid throughout - Reflexes: Absent (areflexia) in all extremities - Sensory: Reduced vibration sense at ankles; mild length-dependent sensory loss - Gait: Unable to walk without assistance **Workup:** - **Lumbar puncture:** Albuminocytologic dissociation - elevated protein 185 mg/dL with 3 WBC (normal cell count) - **Nerve conduction studies:** Prolonged distal latencies; slowed conduction velocities; conduction block in multiple nerves - consistent with acute inflammatory demyelinating polyneuropathy (AIDP) - **Stool culture:** Positive for Campylobacter jejuni - **Anti-ganglioside antibodies:** Anti-GM1 positive - **Respiratory monitoring:** Serial NIF and FVC performed q4h **Diagnosis:** Guillain-Barre syndrome (AIDP variant), post-Campylobacter infection **Treatment:** - ICU admission for respiratory monitoring - IV immunoglobulin (IVIG) 0.4 g/kg daily for 5 days - Intubation on day 3 when NIF declined to -20 cmH2O - DVT prophylaxis - Physical therapy for contracture prevention - Autonomic monitoring (blood pressure and heart rate variability) - Gradual weaning from ventilator after 2 weeks - Inpatient rehabilitation for 6 weeks; walking independently at 3 months **Clinical Pearl:** Guillain-Barre syndrome (GBS) is an acute inflammatory polyneuropathy typically following infection (Campylobacter, CMV, EBV) by 1-4 weeks. The molecular mimicry hypothesis explains pathogenesis: antibodies against microbial antigens cross-react with gangliosides on peripheral nerves. The classic presentation is ascending, symmetric weakness with areflexia (LMN pattern only, unlike ALS). CSF shows the characteristic "albuminocytologic dissociation" (high protein, normal cells). Respiratory failure occurs in 30% of patients, making serial respiratory monitoring essential. Treatment with IVIG or plasmapheresis shortens disease course. --- ## Case 3: Bell's Palsy - Facial Nerve Lower Motor Neuron Lesion ### Patient Presentation **Demographics:** 48-year-old male **Chief Complaint:** Left facial weakness noticed upon awakening this morning **History of Present Illness:** A 48-year-old man woke up this morning and noticed the left side of his face felt "stiff." When he looked in the mirror, the left side of his face was drooping. He cannot close his left eye completely and has difficulty eating, with food falling from the left side of his mouth. He noticed decreased taste on the left anterior tongue. He reports mild pain behind his left ear that began yesterday. He denies hearing changes, limb weakness, numbness elsewhere, or recent illness. He has no history of diabetes or immunocompromise. **Physical Examination:** - Vital signs: Normal - General: Well-appearing with obvious left facial asymmetry - Neurological: - Mental status: Normal - Cranial nerves: - CN VII: Complete left facial paralysis affecting BOTH upper and lower face - cannot raise left eyebrow, cannot close left eye (Bell's phenomenon present - eye rolls upward on attempted closure), flat left nasolabial fold, drooping left mouth angle - All other cranial nerves intact including hearing (CN VIII) - Motor, sensory, reflexes: Normal - Gait: Normal - Ear examination: Normal tympanic membrane; no vesicles (excluding Ramsay Hunt) **Workup:** - Clinical diagnosis based on characteristic presentation - No imaging required for typical presentation - Blood glucose: 95 mg/dL (normal) - Lyme serology: Negative (patient lives in endemic area) **Diagnosis:** Bell's palsy (idiopathic facial nerve palsy) **Treatment:** - Prednisone 60 mg daily for 7 days (started within 72 hours of onset) - Eye protection: Artificial tears during day; lubricating ointment and taping eyelid closed at night - Antiviral therapy (valacyclovir) added given moderately severe presentation - Education on expected recovery timeline - Follow-up in 1 week - 80% of facial function recovered by 6 weeks; near-complete recovery by 4 months **Clinical Pearl:** Bell's palsy must be distinguished from central facial weakness (stroke). In Bell's palsy (LMN lesion), the ENTIRE hemiface is weak including the forehead, because the facial nerve itself is damaged. In stroke (UMN lesion), the forehead is SPARED because the upper face receives bilateral cortical innervation - only the contralateral lower face is controlled by one hemisphere. Thus, forehead sparing suggests stroke, while forehead involvement suggests peripheral (LMN) facial nerve palsy. Bell's palsy is thought to result from herpes simplex virus reactivation causing inflammation in the facial canal. --- ## Clinical Image ![Upper vs lower motor neuron facial weakness](case_01_image.jpg) **Image Description:** Comparative illustration demonstrating upper motor neuron (central) facial weakness with forehead sparing versus lower motor neuron (peripheral) facial weakness with complete hemiface involvement including the forehead, illustrating the different innervation patterns. **Attribution:** Image from Wikimedia Commons (https://commons.wikimedia.org/), Creative Commons Attribution-ShareAlike license.