Opening
A catastrophic mystery finally meets its match. As Dr. Souhel Najjar steps into the room of a near-catatonic Susannah Cahalan, a simple drawing test exposes a raging, treatable illness—and transforms terror into a path forward. Biopsy, steroids, and cutting-edge science converge, even as cognitive tests quantify how much of Susannah’s self the disease has stolen.
What Happens
Chapter 26: The Clock
In a hospital room, Rhona Nack and Tom Cahalan sit beside their daughter, who drools, barely blinks, and moves with ataxic stiffness. When Dr. Souhel Najjar arrives—warm, booming, attentive—he listens closely to the history others have overlooked. His own past as a once-dismissed student fuels his refusal to give up on patients.
He speaks to Susannah directly, noting monotone, delayed speech and a flat affect that recalls late-stage Alzheimer’s. Then he asks her to draw a clock. After a hesitant start, Susannah squeezes all the numbers on the right side of the circle. The drawing exposes a neurological, not psychiatric, crisis: inflammation in the brain’s right hemisphere causing neglect of the left visual field. Numbness, paranoia, and seizures suddenly fit into a single pattern, a crucial advance in The Diagnostic Mystery.
Najjar explains that an autoimmune reaction almost certainly drives the inflammation and recommends a brain biopsy to confirm the extent of damage. Sitting beside Susannah, he tells her parents, “Her brain is on fire.” Susannah briefly returns—tears, a hug—and he restates it plainly: her brain is under attack by her own body. For the first time, hope feels real.
Chapter 27: Brain Biopsy
Najjar outlines options—steroids now, or biopsy first to confirm the target. Terrified yet trusting, Tom darts into a chapel to pray while Rhona, an “agnostic Jewish girl,” joins coworkers in prayer—a moment of Love and Family Support under crushing fear. Susannah, adrift, texts friends about her upcoming “briannopsy,” laughing off the danger until a worried reply makes her cry.
On surgery day, she sits calm as her head is shaved. Tom offers their family motto—“What’s the slope of the line?”—and she signals “Positive.” Neurosurgeon Dr. Werner Doyle performs a frameless stereotactic biopsy, removing a cube of tissue from her right frontal cortex. The clinical precision of the four-hour operation contrasts sharply with Susannah’s fragmented, dreamlike impressions of what follows, a vivid instance of Memory and Unreliable Narration.
In recovery, a brusque nurse denies her water. Susannah becomes convinced she cannot move her legs, sending Tom into panic. An emergency MRI shows no injury; the deficit exists only in perception. The gap between what her brain tells her and what her body can do widens—and terrifies.
Chapter 28: Shadowboxer
Post-op on the epilepsy floor, the pathology report confirms Najjar’s suspicion: severe brain inflammation with immune cells swarming neurons. A primer on the blood-brain barrier explains how the brain’s defenders have breached their post and turned inward. Doctors launch treatment: three days of high-dose IV Solu-Medrol to tamp down the immune system and calm the fire.
The steroids trigger complications, including temporary type II diabetes. Symptoms don’t ease immediately; if anything, panic and abnormal movements intensify. Tom’s log notes a “strange smirking expression,” tense shaking, and episodes of rigidity. An EEG video captures Susannah’s halting, painfully slow motions while Rhona flutters nearby—an almost unbearable juxtaposition. Still, with friends like Hannah, Susannah jokes about her bandaged, shaved head, proof that shards of her old self still surface.
Chapter 29: Dalmau’s Disease
Inflammation is certain; its cause is not. Dr. Russo confides in Rhona that she and Najjar have a “bet”: Russo suspects a paraneoplastic syndrome—an immune response to hidden cancer—while Najjar believes a primary autoimmune encephalitis. The word cancer devastates Rhona. Spinal fluid and blood go to the University of Pennsylvania for analysis by Dr. Josep Dalmau, the leading expert on a rare autoimmune disease.
The narrative zooms out to Dalmau’s scientific detective story. In 2005, he spots a pattern in four young women with psychiatric collapse, seizures, and ovarian tumors. His lab work with rat brains reveals a shared antibody attacking a single neural target: the NMDA receptor, essential for learning, memory, and behavior. When antibodies block these receptors, neural communication breaks down, producing psychosis, catatonia, seizures, and, without treatment, death.
Dalmau names the illness anti-NMDA-receptor autoimmune encephalitis. By the time Susannah’s samples arrive, he has identified 216 cases worldwide. The chapter ends with a chilling implication: if it takes this long at a top hospital, how many people are languishing, misdiagnosed in psychiatric wards?
Chapter 30: Rhubarb
Two days after the biopsy, clinicians establish a cognitive and speech baseline that quantifies The Fragility of Identity and Loss of Self. Speech pathologist Karen Gendal diagnoses aphasia and dysarthria. Asked why she is hospitalized, Susannah struggles and finally says, “I can’t get my ideas from my head out.” She substitutes similar-sounding words (“ken” for “pen”) and scrawls nearly illegible handwriting.
Neuropsychologist Chris Morrison follows with extensive testing. Susannah’s working memory stalls at five digits; normal is seven. In one minute, a healthy person can list 20+ fruits and vegetables; Susannah musters five—apples, carrots, pears, bananas, and “rhubarb.” She fails to name common pictured objects and cannot reproduce simple block patterns.
Throughout, Morrison observes a painful combination: insight into her deficits and mounting frustration at tasks once easy. He notes her tenacity—and her failures—and strongly recommends cognitive therapy, the first step toward rebuilding what the disease eroded.
Character Development
These chapters plunge the characters to their lowest point and then pivot toward rescue, revealing courage, acuity, and the resilience of family.
- Susannah: At her nadir—catatonic, rigid, and unreliable as a narrator—she still flashes through: tears as Najjar names her condition, humor with friends, and acute self-awareness during testing. Her frustration at cognitive tasks exposes a self fighting to reemerge.
- Dr. Souhel Najjar: Empathetic and relentless, he reframes the entire case with one elegant test. His personal history with being underestimated informs his refusal to dismiss patients—and makes him the story’s diagnostic hero.
- Tom Cahalan: Protective and visibly shaken, he clings to ritual and reason. His “slope of the line” mantra becomes a lifeline that steadies both father and daughter.
- Rhona Nack: Fiercely present, she oscillates between rational advocacy and spiritual seeking. Anxiety crackles around her, but she never stops pressing for answers.
Themes & Symbols
The diagnostic mystery reaches its fulcrum. The clock test reframes Susannah’s collapse from psychiatric chaos to neurological disease, replacing stigma with a hypothesis that medicine can test and treat. That shift—from narrative confusion to investigative clarity—reorients the entire story.
Mind and body entwine in every scene. A childlike drawing exposes hemispatial neglect; a biopsy yields tissue that explains terror; steroids stir hope and side effects; MRIs disprove perceived paralysis. The case demonstrates how physical insult produces psychic fracture—and how repairing the body can restore the self.
The fragility of identity becomes measurable. Word-finding failures, garbled handwriting, and a five-digit memory span turn abstract loss into data points. Those numbers—humbling, clinical, precise—double as a roadmap for recovery.
Symbol: The clock is the book’s visual lodestar. A perfect circle crammed with right-sided numbers makes the invisible visible: one hemisphere inflamed, one half of space abandoned. It marks the exact moment the story turns toward cure.
Key Quotes
“Her brain is on fire.”
Najjar’s metaphor translates complex immunology into visceral clarity. It unites family and clinicians around an urgent, treatable target and supplies the book’s defining image.
“Her brain is under attack by her own body.”
The line names the enemy and the battlefield. By identifying an autoimmune process, it points away from psychiatry and toward immunotherapy and targeted diagnostics.
“What’s the slope of the line?” — “Positive.”
Father and daughter share a private calculus of hope. The exchange steadies Susannah and gives Tom agency, compressing terror into a promise of upward progress.
“I can’t get my ideas from my head out.”
This confession distills aphasia into a single, heartbreaking sentence. It captures the intact self trapped behind broken pathways, clarifying both the damage and the goal of therapy.
“briannopsy”
Susannah’s glib, misspelled text is darkly comic and chilling. It showcases cognitive slippage and emotional detachment while foreshadowing the shock that breaks through when a friend responds with concern.
Why This Matters and Section Significance
This stretch of the memoir is the hinge on which the entire narrative turns. Najjar’s arrival ends freefall, the clock test makes the invisible legible, and the biopsy plus steroids initiate a plan. Dalmau’s research anchors Susannah’s ordeal in a global medical context, exposing a gap that strands countless patients between psychiatry and neurology. By pairing clinical precision with subjective chaos, the chapters shift the book from mystery to recovery and lay the groundwork for a methodical climb back to self.