In a catatonic patient at risk for mild cognitive impairment, is a single‑photon emission computed tomography (SPECT) scan indicated as a routine investigation?

SPECT Scan in Catatonic Patients at Risk for MCI

SPECT scanning is not indicated as a routine investigation in a catatonic patient at risk for mild cognitive impairment (MCI), as advanced functional imaging should only be pursued after baseline clinical evaluation, structural brain imaging (MRI or CT), and specialist assessment when the underlying pathological process remains unclear. 1

Why SPECT is Not Appropriate in This Clinical Context

Primary Diagnostic Priorities in Catatonia

• Catatonia requires immediate medical and psychiatric evaluation to identify treatable causes (metabolic derangements, infections, medication effects, underlying psychiatric disorders) rather than functional brain imaging. 1
• The presence of catatonia represents an acute neuropsychiatric emergency that demands structural imaging (CT or MRI) to exclude masses, strokes, or other acute structural pathology—not functional imaging like SPECT. 2

MCI Risk Does Not Justify SPECT

• Cognitive screening for asymptomatic individuals or those merely "at risk" for MCI is explicitly not recommended, even in patients with risk factors such as family history or vascular risk factors. 1
• SPECT is reserved for patients who already have an established diagnosis of cognitive impairment and have undergone comprehensive evaluation by a cognitive disorders specialist, yet the underlying pathological process remains unclear. 1

Appropriate Diagnostic Algorithm

Step 1: Address the Catatonia First

• Obtain MRI (preferred) or CT to exclude structural causes of catatonia including masses, strokes, encephalitis, or other acute pathology. 2
• Evaluate for metabolic, infectious, and medication-related causes of catatonia through appropriate laboratory testing. 1

Step 2: Cognitive Assessment Only If Clinically Indicated

• Do not screen for MCI in asymptomatic patients—cognitive testing should only occur if there are actual clinical concerns such as reported cognitive symptoms, unexplained decline in instrumental activities of daily living, missed appointments, or difficulty following instructions. 1
• If cognitive concerns emerge after catatonia resolves, validated cognitive assessments should be performed before considering any advanced imaging. 1

Step 3: Advanced Imaging Only After Specialist Evaluation

• FDG-PET (not SPECT) is the preferred functional imaging modality if a cognitive disorders specialist has evaluated the patient and the underlying pathological process remains unclear after baseline clinical and structural imaging. 1, 3
• SPECT should only be considered if FDG-PET is not practically available, and only after the above conditions are met. 1

Critical Pitfalls to Avoid

• Do not order SPECT for "risk" of MCI—there is insufficient evidence to support routine clinical use of SPECT at the individual patient level for screening purposes. 1
• Do not bypass structural imaging—MRI or CT must be obtained first to exclude treatable structural abnormalities. 2
• Do not skip specialist evaluation—functional imaging like SPECT requires prior assessment by a cognitive disorders specialist to determine if it will actually change clinical management. 1

When SPECT Might Eventually Be Considered

SPECT cerebral blood flow studies have a limited role only in the following specific scenario:

• The patient has established cognitive impairment (not just "at risk"). 1
• Baseline clinical evaluation and structural brain imaging (MRI/CT) have been completed. 1
• A cognitive disorders specialist has evaluated the patient. 1
• The underlying pathological process remains unclear, preventing adequate clinical management. 1
• FDG-PET is not practically available. 1

In the specific case of a catatonic patient merely "at risk" for MCI, none of these conditions are met, making SPECT inappropriate. 1