# Clinical Cases: Dementia and Cognitive Disorders

## Case 1: Alzheimer's Disease

### Patient Demographics
- **Age:** 72 years
- **Sex:** Female
- **Occupation:** Retired school principal

### Chief Complaint
Family: "She keeps asking the same questions and got lost driving to church."

### History of Present Illness
The patient's family has noticed progressive memory problems over the past 2-3 years. She frequently misplaces items and accuses family members of stealing. She asks the same questions repeatedly, even after just being told the answer. She recently got lost driving to her church of 40 years. She has missed appointments and bill payments. She has difficulty following recipes she has made for decades. She sometimes struggles to find words in conversation. She has become withdrawn from social activities she previously enjoyed. She has preserved motor function and can perform basic self-care. Her husband manages medications as she was taking pills at the wrong times. No hallucinations. No sudden worsening.

### Neurological Examination Findings

**Mental Status Examination:**
- **MMSE Score: 18/30** (mild-moderate impairment)
  - Orientation: 3/10 (lost points for date, day, month, year, floor, county)
  - Registration: 3/3
  - Attention/Calculation: 1/5 (serial 7s)
  - **Recall: 0/3** (unable to recall any words at 5 minutes) - key finding
  - Language: 7/9 (anomia for "watch stem")
  - Visuospatial: Cannot copy intersecting pentagons
- **MoCA Score: 14/30**
- Clock drawing: Disorganized, numbers scattered

**Cranial Nerves:**
- Intact II-XII
- No anosmia (unlike Lewy body dementia)

**Motor Examination:**
- 5/5 strength throughout
- Normal tone (no rigidity)
- No tremor
- No myoclonus

**Sensory Examination:**
- Intact

**Reflexes:**
- 2+ symmetric
- No frontal release signs initially
- Plantar responses flexor

**Coordination:**
- Normal finger-to-nose, heel-to-shin

**Gait:**
- Normal base, normal speed
- No parkinsonian features

### Cognitive Domain Assessment

| Domain | Finding | Interpretation |
|--------|---------|----------------|
| Memory | Cannot learn new information, poor recall | Hippocampal dysfunction - hallmark |
| Executive | Impaired planning, judgment | Frontal involvement |
| Language | Word-finding difficulty (anomia) | Temporal-parietal |
| Visuospatial | Impaired clock drawing | Parietal involvement |
| Behavior | Apathy, social withdrawal | Common in AD |

### Neuro Workup
- **Laboratory Studies (to exclude reversible causes):**
  - TSH: Normal
  - B12: Normal
  - CBC, CMP: Normal
  - RPR: Non-reactive
  - HIV: Negative
- **MRI Brain:**
  - **Bilateral hippocampal atrophy** (medial temporal lobe) - characteristic
  - Temporal and parietal cortical atrophy
  - No significant white matter disease
  - No infarcts
- **FDG-PET (if diagnostic uncertainty):**
  - Hypometabolism in temporoparietal regions bilaterally
  - Posterior cingulate hypometabolism (early finding)
- **Amyloid PET or CSF biomarkers (if available):**
  - CSF: Low Aβ42, elevated tau and p-tau
  - Amyloid PET: Positive (not required for diagnosis)

### Diagnosis
**Probable Alzheimer's Disease Dementia** (NIA-AA criteria 2011)
- Insidious onset, progressive cognitive decline
- Amnestic presentation (memory most affected)
- Impairment in ≥2 cognitive domains
- Interferes with daily function
- Not explained by delirium or other conditions

### Management

**Pharmacological Treatment:**
1. **Cholinesterase inhibitor:** Donepezil 5 mg daily, increase to 10 mg after 4-6 weeks
   - Alternatives: Rivastigmine, galantamine
   - Modest symptomatic benefit (does not stop progression)
2. **NMDA receptor antagonist:** Add memantine 5 mg daily, titrate to 10 mg BID
   - For moderate-severe AD
   - Can combine with cholinesterase inhibitor
3. **Anti-amyloid monoclonal antibodies (newer):**
   - Lecanemab, donanemab - for early AD with confirmed amyloid
   - Slows cognitive decline modestly
   - Requires amyloid PET or CSF confirmation
   - Risk of ARIA (amyloid-related imaging abnormalities)

**Behavioral Symptom Management:**
1. Agitation/aggression: Non-pharmacological first; if needed, low-dose SSRI, trazodone
2. Depression: SSRI (sertraline, escitalopram)
3. Sleep disturbance: Sleep hygiene, low-dose trazodone
4. **Avoid:** Anticholinergics, benzodiazepines, typical antipsychotics

**Non-Pharmacological Interventions:**
1. Structured daily routine
2. Cognitive stimulation activities
3. Physical exercise
4. Social engagement
5. Caregiver education and support

**Safety Assessment:**
1. **Driving evaluation** - recommend stopping based on getting lost
2. Home safety evaluation (stove, firearms, medications)
3. Medical alert bracelet
4. Consider tracking devices

**Caregiver Support:**
1. Alzheimer's Association resources
2. Support groups
3. Respite care
4. Financial and legal planning (while patient can participate)

**Advance Care Planning:**
1. Establish healthcare proxy/durable power of attorney
2. Discuss goals of care, code status
3. Consider palliative care as disease progresses

### Clinical Image
![Alzheimer's Disease MRI](case_01_image.jpg)

**Image Description:** Coronal T1-weighted MRI showing bilateral hippocampal atrophy and enlarged temporal horns of the lateral ventricles, characteristic findings in Alzheimer's disease.

**Attribution:** Image from Radiopaedia.org, Case courtesy of Dr. Frank Gaillard. Licensed under CC BY-NC-SA 3.0. Source: https://radiopaedia.org/cases/alzheimer-disease-2

---

## Case 2: Lewy Body Dementia

### Patient Demographics
- **Age:** 74 years
- **Sex:** Male
- **Occupation:** Retired electrician

### Chief Complaint
"He sees children in the room who aren't there, and some days he's fine, other days he's very confused."

### History of Present Illness
The patient's wife reports that over the past 18 months, he has experienced episodes of confusion with marked day-to-day (and even hour-to-hour) fluctuation. Some mornings he is nearly normal; other times he is extremely confused and somnolent. He has been seeing "little children playing in the living room" - visual hallucinations that are vivid, detailed, and non-threatening. He knows they are not real but still sees them. He has developed a shuffling gait and moves slowly. He acts out his dreams - shouting, punching, and kicking during sleep (REM sleep behavior disorder). His wife reports he has had two falls. He was recently started on haloperidol for agitation at an urgent care, which made him severely rigid and nearly unresponsive (neuroleptic sensitivity).

### Neurological Examination Findings

**Mental Status:**
- Fluctuating attention - alert during exam but wife reports prolonged staring spells
- MMSE: 20/30 (impaired attention and visuospatial)
- Clock drawing: Severely impaired
- Recall: 2/3 (better than expected for dementia)
- Detailed visual hallucinations reported

**Cranial Nerves:**
- Hypomimia (masked facies)
- Reduced blink rate
- Mild hypophonia

**Motor Examination:**
- **Parkinsonian features:**
  - Bilateral bradykinesia (slow finger taps)
  - Cogwheel rigidity at wrists and elbows
  - Mild rest tremor (less prominent than idiopathic PD)
- Strength: 5/5

**Sensory Examination:**
- Intact

**Reflexes:**
- 2+ symmetric
- No frontal release signs

**Coordination:**
- Slowed movements

**Gait:**
- Short, shuffling steps
- Reduced arm swing
- Stooped posture
- Postural instability (positive pull test)

### Diagnostic Criteria
**Revised Criteria for Dementia with Lewy Bodies (McKeith 2017):**
- **Essential:** Dementia with progressive cognitive decline
- **Core Features (≥2 = probable DLB):**
  1. ✓ Fluctuating cognition with pronounced variations in attention/alertness
  2. ✓ Recurrent visual hallucinations (typically well-formed, detailed)
  3. ✓ REM sleep behavior disorder
  4. ✓ Parkinsonism
- **Supportive features:** Severe neuroleptic sensitivity, postural instability, falls, autonomic dysfunction, depression

**This patient has all 4 core features = Probable DLB**

### Neuro Workup
- **MRI Brain:**
  - Mild generalized atrophy
  - Relative preservation of hippocampi (unlike AD)
  - No significant vascular disease
- **DaTscan (dopamine transporter SPECT):**
  - **Reduced dopaminergic uptake in basal ganglia bilaterally** (supportive biomarker)
  - Helps differentiate DLB from AD
- **Polysomnography:**
  - REM sleep without atonia
  - Dream enactment behavior
- **FDG-PET:**
  - Posterior cortical hypometabolism with occipital involvement ("cingulate island sign")
- **EEG:**
  - Posterior slowing with fluctuations

### Diagnosis
**Probable Dementia with Lewy Bodies (DLB)**

### Management

**Cognitive Symptoms:**
1. **Cholinesterase inhibitor:** Rivastigmine 1.5 mg BID, titrate up
   - DLB patients often have more cholinergic deficit
   - May also improve hallucinations
2. Memantine: Can be added

**Visual Hallucinations:**
1. If non-distressing: Reassurance, no treatment needed
2. If distressing: Low-dose quetiapine 12.5-25 mg (least D2 blocking)
3. Pimavanserin (selective 5-HT2A inverse agonist) - approved for PD psychosis
4. **AVOID:** Haloperidol, risperidone, olanzapine - neuroleptic sensitivity can be fatal

**Parkinsonian Symptoms:**
1. Carbidopa/levodopa 25/100 TID - careful, lower doses
   - May worsen hallucinations
   - Start low, go slow
2. Avoid anticholinergics for PD (worsen cognition)
3. Physical therapy for gait and balance

**REM Sleep Behavior Disorder:**
1. Melatonin 3-12 mg at bedtime (first-line)
2. Clonazepam 0.25-0.5 mg at bedtime (second-line)
3. Bed safety measures (remove sharp objects, pad bed rails)

**Autonomic Dysfunction:**
1. Orthostatic hypotension: Compression stockings, midodrine, fludrocortisone
2. Constipation: Fiber, PEG

**Safety:**
1. Fall prevention (PT, home safety)
2. Driving cessation (hallucinations + parkinsonism)
3. Supervision during fluctuating episodes

**Caregiver Education:**
1. Expect fluctuations - good days and bad days
2. Do not argue about hallucinations
3. Watch for neuroleptic sensitivity if hospitalized
4. Medical alert bracelet indicating medication sensitivities

### Clinical Image
![Lewy Body Dementia DaTscan](case_02_image.jpg)

**Image Description:** DaTscan showing reduced dopamine transporter uptake in the bilateral striatum, a supportive biomarker for dementia with Lewy bodies.

**Attribution:** Image from Radiopaedia.org, Case courtesy of Dr. Ian Bickle. Licensed under CC BY-NC-SA 3.0. Source: https://radiopaedia.org/cases/dementia-with-lewy-bodies-2

---

## Case 3: Normal Pressure Hydrocephalus (NPH)

### Patient Demographics
- **Age:** 78 years
- **Sex:** Male
- **Occupation:** Retired postal worker

### Chief Complaint
"He walks like his feet are glued to the floor, and he's been having accidents."

### History of Present Illness
The patient's family has noticed progressive gait difficulty over the past 1 year. He takes small, shuffling steps and appears to have trouble lifting his feet, as if they are "magnetized to the floor." He has had multiple falls. Concurrently, he has developed urinary urgency progressing to urinary incontinence over the past 6 months. His memory has also declined, but the family emphasizes the gait and bladder problems came first and are more prominent. He previously walked 2 miles daily and was cognitively intact. No headaches or visual symptoms.

### Neurological Examination Findings

**Mental Status:**
- MMSE: 24/30
- Impaired attention and concentration
- Psychomotor slowing
- Impaired recall (2/3) but improves with cueing (subcortical pattern)
- No aphasia

**Cranial Nerves:**
- Intact II-XII
- No papilledema

**Motor Examination:**
- 5/5 strength throughout
- Normal tone (no rigidity)
- No tremor

**Sensory Examination:**
- Intact

**Reflexes:**
- 2+ symmetric
- Plantar responses flexor (or mildly extensor from frontal dysfunction)

**Coordination:**
- Finger-to-nose: Normal
- Heel-to-shin: Normal

**Gait (hallmark finding):**
- **Magnetic gait:** Feet appear stuck to floor
- Wide-based
- Short steps, shuffling
- Start hesitation (difficulty initiating)
- Turn en bloc
- Reduced foot clearance
- Relatively preserved arm swing (unlike PD)
- "Lower body parkinsonism"

**Bladder:**
- Urgency, urge incontinence (detrusor overactivity)

### Classic Triad of NPH (Hakim's Triad)
1. **Gait disturbance** - usually first and most prominent
2. **Urinary incontinence** - urge type, then incontinence
3. **Dementia** - frontal-subcortical pattern, often least prominent

**Mnemonic: "Wet, Wacky, and Wobbly"**

### Neuro Workup
- **MRI Brain:**
  - **Ventriculomegaly out of proportion to sulcal atrophy** (Evans index >0.3)
  - Evans index: Maximal frontal horn width / biparietal diameter >0.3
  - Rounded frontal horns
  - Callosal angle <90 degrees (acute)
  - Periventricular T2 hyperintensity (transependymal CSF flow)
  - Aqueductal flow void present (patent aqueduct)
- **Lumbar Puncture with High-Volume Tap:**
  - **Opening pressure: 16 cm H2O** (normal or mildly elevated - distinguishes from obstructive hydrocephalus)
  - Remove 30-50 mL CSF
  - CSF analysis: Normal
  - **Clinical response to tap:** Gait improved significantly 1-2 hours post-LP and over 24-48 hours
- **Pre- and Post-LP Gait Assessment:**
  - 10-meter walk time: 28 seconds pre-LP → 18 seconds post-LP (>20% improvement = positive)
  - Timed Up and Go: Improved
- **Continuous Lumbar Drainage (if uncertain):** 3-day trial with daily assessments

### Diagnosis
**Idiopathic Normal Pressure Hydrocephalus (iNPH)** - probable (positive tap test)

### Management

**Surgical Treatment:**
1. **Ventriculoperitoneal (VP) shunt placement** - definitive treatment
   - Programmable valve preferred (allows pressure adjustments)
   - Response rate: 70-90% for gait, 50-70% for cognition, 50% for incontinence
2. **Endoscopic third ventriculostomy (ETV)** - alternative in some cases

**Predictors of Good Shunt Response:**
1. Gait predominant symptoms
2. Shorter duration of symptoms
3. Known etiology (SAH, meningitis) vs idiopathic
4. Robust response to large-volume LP
5. Less cognitive impairment

**Post-Shunt Monitoring:**
1. Follow gait, cognition, and continence
2. Adjust programmable valve if under- or over-drainage
3. Watch for complications:
   - Subdural hematoma (from over-drainage)
   - Shunt infection
   - Shunt malfunction

**Conservative Management (if not surgical candidate):**
1. Serial large-volume LPs (temporary improvement)
2. Physical therapy for gait
3. Bladder management (scheduled voiding, anticholinergics cautiously)
4. Fall prevention

**Differential Diagnosis Considered:**
1. Parkinson's disease (has tremor, rigidity, asymmetry)
2. Vascular dementia/parkinsonism (significant white matter disease)
3. Progressive supranuclear palsy (vertical gaze palsy, axial rigidity)
4. Alzheimer's disease (memory predominant, no gait early)

### Clinical Image
![Normal Pressure Hydrocephalus MRI](case_03_image.jpg)

**Image Description:** Axial T2-weighted MRI showing ventriculomegaly with enlarged lateral ventricles out of proportion to sulcal atrophy, characteristic of normal pressure hydrocephalus.

**Attribution:** Image from Radiopaedia.org, Case courtesy of Dr. Ahmed Abd Rabou. Licensed under CC BY-NC-SA 3.0. Source: https://radiopaedia.org/cases/normal-pressure-hydrocephalus-11