What are the appropriate diagnostic steps and treatment options for a patient experiencing a change in level of consciousness, tremors, and weakness?

Acute Change in Level of Consciousness with Tremors and Weakness

For a patient presenting with acute change in level of consciousness, tremors, and weakness, immediately assess using the FOUR score (not Glasgow Coma Scale) and initiate ABCDE resuscitation protocol while simultaneously pursuing urgent neuroimaging to identify life-threatening structural causes. 1, 2, 3

Immediate Assessment and Stabilization

Primary Survey (ABCDE Protocol)

• Airway and Breathing: Administer supplemental oxygen if saturation <94% or unknown, as hypoxemia exacerbates brain injury and worsens outcomes 4
• Circulation: Establish IV access and obtain point-of-care glucose immediately—hypoglycemia is a reversible cause that must be excluded within minutes 3
• Disability (Neurological): Use the FOUR score rather than Glasgow Coma Scale for this presentation, as it provides superior assessment for severely affected patients and evaluates brainstem reflexes critical for detecting deterioration 1, 5
• Exposure: Check for skin abnormalities, signs of trauma, needle marks, or rashes that suggest specific etiologies 3

Critical "Red Flags" Requiring Immediate Action

• Pupillary abnormalities: Suggest structural brainstem lesion or herniation 3
• Focal neurological deficits: Indicate stroke, hemorrhage, or mass lesion requiring emergent imaging 3
• Meningismus with fever: Suggests meningitis/encephalitis requiring immediate lumbar puncture and empiric antibiotics 3
• Progression of motor posturing: Decorticate to decerebrate posturing indicates rostral-caudal deterioration and impending herniation 2

Diagnostic Workup

Immediate Laboratory Testing

• Point-of-care glucose, electrolytes (sodium, calcium), renal function, liver function, ammonia 3
• Complete blood count, toxicology screen, blood cultures if febrile 3
• Arterial blood gas if respiratory abnormalities present 3
• Approximately 20% of cases have metabolic or infectious causes, and one-third have multiple underlying conditions 3

Urgent Neuroimaging

• Non-contrast CT head immediately to exclude hemorrhage, mass effect, or hydrocephalus 3
• MRI brain with diffusion-weighted imaging if CT non-diagnostic and patient stable enough for transfer—superior for detecting acute ischemia, posterior fossa lesions, and encephalitis 4, 1
• For post-traumatic cases specifically, MRI at 6-8 weeks evaluating corpus callosum, dorsolateral brainstem, and corona radiata provides prognostic information (Level B recommendation) 4, 1

Electrophysiological Studies

• Standard EEG within 24 hours to detect non-convulsive status epilepticus—visual analysis has high specificity for detecting preserved consciousness 4, 1
• Quantitative high-density EEG should be considered if standard EEG non-diagnostic and consciousness disorder persists beyond acute phase 4, 1
• EEG reactivity at 2-3 months post-injury helps predict 12-month recovery in traumatic cases 4

Specialized Assessment for Prolonged Disorders of Consciousness

• Coma Recovery Scale-Revised (CRS-R) is the reference standard for behavioral assessment if impaired consciousness persists beyond acute phase—significantly reduces misdiagnosis compared to other scales 1, 5
• FOUR score serial assessments to monitor for neurological deterioration, particularly progression from decorticate to decerebrate posturing 2, 5

Tremor-Specific Evaluation

Characterize Tremor Phenomenology

• Rest tremor: Suggests parkinsonian etiology—examine for bradykinesia, rigidity, postural instability 6, 7
• Action tremor: Most commonly enhanced physiological tremor (metabolic, toxic) or essential tremor 6, 8
• Frequency and amplitude: High-frequency, low-amplitude suggests metabolic/toxic; lower frequency suggests structural or parkinsonian 6

Critical Tremor Red Flags in Acute Setting

• Acute onset tremor with altered consciousness: Consider metabolic derangement (hyperthyroidism, hypoglycemia, hepatic encephalopathy), drug intoxication/withdrawal (alcohol, benzodiazepines), or structural lesion 3, 6
• Tremor with fever and confusion: Suggests neuroleptic malignant syndrome, serotonin syndrome, or CNS infection 9
• Asymmetric tremor with weakness: Indicates structural brain lesion requiring urgent imaging 6

Weakness Assessment

Distinguish Focal vs. Generalized Weakness

• Focal weakness with altered consciousness: Stroke until proven otherwise—use NIH Stroke Scale to quantify deficits 4
• Symmetric weakness: Consider neuromuscular junction disorders (myasthenia crisis), Guillain-Barré syndrome, or metabolic causes 3
• Motor posturing patterns: Decorticate (arm flexion, leg extension) indicates cortical/internal capsule damage; decerebrate (all extremities extended) indicates midbrain/upper brainstem involvement 2

Urgent Stroke Protocol if Indicated

• Activate stroke team if focal deficits present with symptom onset <24 hours 4
• Use Cincinnati Prehospital Stroke Scale (facial droop, arm drift, speech abnormalities)—single abnormality has 59% sensitivity, 89% specificity 4
• Establish precise time of symptom onset or last known normal—this is "time zero" for treatment decisions 4

Common Diagnostic Pitfalls

• Sedatives, analgesics, and neuromuscular blockade confound neurological examination—review medication administration times and consider reversal agents 1, 2, 5
• Absence of behavioral response does not equal absence of consciousness—up to 40% of patients diagnosed as vegetative state actually have some level of consciousness detectable only by advanced techniques 1
• Psychiatric causes are diagnoses of exclusion—thoroughly exclude medical/neurological causes first, as primary psychiatric conditions rarely present with true altered consciousness 9
• Multiple simultaneous etiologies occur in one-third of cases—continue diagnostic workup even after identifying one cause 3

Prognosis and Advanced Assessment

For Traumatic Brain Injury Cases

• SPECT scan at 1-2 months post-injury assists in predicting 12-month recovery and degree of disability (Level B recommendation) 4, 1
• Functional MRI with active paradigms at 1-60 months post-injury may detect covert consciousness in patients without command-following at bedside 4, 1

For Anoxic Brain Injury Cases

• Somatosensory evoked potentials (SEPs) may assist in predicting consciousness recovery at 24 months 4, 1

Multimodal Assessment Approach

• FDG-PET scan should be considered as part of multimodal evaluation in persistently unresponsive patients 4, 1
• Resting-state fMRI should be added to any indicated structural MRI to evaluate default mode network 4, 1

Mortality and Outcome Considerations

• Overall mortality in acute impaired consciousness is 10%, with 45-50% having primary neurological causes 3
• Rapid progression of motor posturing (decorticate to decerebrate within 20 minutes) indicates poor prognosis and warrants immediate neurosurgical consultation 2
• Patients with severely impaired consciousness, status epilepticus, absent protective reflexes, or acute neurological deficits require ICU admission 3