What could explain recurrent episodic brief sensations of 'brain being touched' in a patient with normal neurological examination, no history of trauma, and normal brain Magnetic Resonance Imaging (MRI)?

Likely Diagnosis: Focal Sensory Seizures (Simple Partial Seizures)

The recurrent, stereotyped, brief (10-20 second) episodes of abnormal sensation described as "brain being touched" most likely represent focal sensory seizures, despite the normal neurological examination and normal brain MRI. 1

Clinical Reasoning

Why Seizures Are the Leading Diagnosis

• Stereotyped, brief episodes lasting 10-20 seconds occurring recurrently over 2 months fit the classic pattern of focal seizures, which can present with isolated sensory phenomena without loss of consciousness or motor manifestations 1

• Normal neurological examination does NOT exclude epilepsy - in fact, most patients with focal epilepsy have completely normal interictal neurological examinations 1

• Normal brain MRI does NOT exclude seizure disorder - MRI detects structural lesions in only 30-70% of focal epilepsy cases, meaning 30-70% of patients with confirmed epilepsy have normal MRI findings 1

Specific Features Supporting Seizure Diagnosis

• The brief duration (10-20 seconds) is characteristic of simple partial seizures, which typically last seconds to 1-2 minutes 1

• The recurrent episodic nature with symptom-free intervals between episodes is pathognomonic for seizures rather than structural lesions or continuous processes 1

• The unusual sensory quality ("brain being touched") represents a focal sensory aura, which can manifest as paresthesias, unusual sensations, or indescribable feelings originating from sensory cortex 1

Recommended Diagnostic Workup

Essential Next Step: Electroencephalography (EEG)

• Obtain an EEG as the primary diagnostic test - this is the most appropriate investigation for suspected focal seizures with normal MRI 1

• An abnormal EEG significantly increases the likelihood of epilepsy diagnosis, though a normal EEG does not exclude it (16% of patients with confirmed epilepsy had normal initial EEG) 1

• Focal epileptiform discharges, focal slowing, or ictal patterns would confirm the diagnosis and guide treatment decisions 1

When to Reconsider Imaging

• MRI with epilepsy protocol should be considered if initial standard MRI was not optimized for seizure evaluation - this includes high-resolution coronal T2, FLAIR sequences, and 3D volumetric sequences to detect subtle cortical dysplasia or hippocampal abnormalities 1

• The absence of red flags (no fever, no persistent altered mental status, no focal neurological deficits, no recent trauma, no headache, no history of cancer, no anticoagulation) makes urgent repeat imaging unnecessary 1

Alternative Diagnoses to Consider (Less Likely)

Migraine Aura Without Headache

• Migraine auras typically last 5-60 minutes (not 10-20 seconds) and usually progress or march over time, making this diagnosis less compatible with the brief, stereotyped episodes described 1, 2

• The prevalence of significant abnormalities in migraine patients with normal neurological examination is only 0.2%, similar to the general asymptomatic population 1, 2

Transient Ischemic Attacks (TIAs)

• TIAs are unlikely given the young age (implied by "no major illness"), brief duration, and recurrent identical episodes - TIAs typically last minutes to hours and vary in presentation 1

Peripheral Nerve or Psychiatric Etiology

• The specific localization to "brain being touched" and episodic nature make peripheral neuropathy unlikely 1

• Psychiatric symptoms (anxiety, panic attacks) should be considered but typically have longer duration, associated autonomic symptoms, and different triggers 3, 4

Management Approach

Immediate Actions

• Refer to neurology for EEG and consideration of antiepileptic therapy if seizures are confirmed 1

• Counsel the patient on seizure precautions including avoiding driving, swimming alone, working at heights, or operating dangerous machinery until diagnosis is clarified 1

• Document seizure characteristics precisely: exact duration, frequency, any triggers, presence of post-ictal symptoms, and any progression 1

Common Pitfall to Avoid

• Do not be falsely reassured by normal MRI and normal neurological examination - these findings are common in focal epilepsy and do not exclude the diagnosis 1

• Do not dismiss brief sensory symptoms as "anxiety" or "stress" without proper neurological evaluation - focal sensory seizures are frequently misdiagnosed initially 1