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The image is from a neurology textbook and covers Parkinson's Disease - specifically the festinant gait and its diagnosis/management. Here is a full explanation:

Festinant Gait in Parkinson's Disease

What the Figure Shows (Fig. 108.7)

The diagram illustrates festinant gait (from Latin festinare - to hurry), the characteristic walking pattern of Parkinson's disease. The sequential panels show:
  • The patient bends forward at the trunk (flexed posture)
  • Takes rapid, short, shuffling steps
  • The feet barely lift off the ground
  • The patient appears to be "chasing" their own center of gravity - rushing forward as if trying not to fall
This gait results from the combination of bradykinesia (slowness of movement), rigidity, and loss of postural reflexes that are hallmarks of Parkinson's disease. The body leans forward while the feet cannot keep pace, creating an accelerating, shuffling run.

Diagnosis

Functional dopaminergic imaging by SPECT is used to confirm the diagnosis. Here is what happens:
  • In Parkinson's disease, dopaminergic neurons in the substantia nigra pars compacta degenerate
  • These neurons project to the striatum (caudate + putamen) via the nigrostriatal pathway
  • On SPECT imaging, uptake of dopaminergic markers is reduced, particularly in the posterior putamen - the region that controls motor function
  • The pattern is described as a "period/full-stop" appearance (reduced signal restricted to caudate) vs. the normal "comma" appearance (robust uptake in both caudate and putamen)

DaT (Dopamine Transporter) Imaging

  • Uses radiolabeled ligands (e.g., [¹²³I]FP-CIT / DaTSCAN) that bind to dopamine transporters on dopaminergic nerve terminals
  • Measures the density of nigrostriatal dopaminergic terminals - reduced in Parkinson's disease and related syndromes
  • Helps distinguish true Parkinson's disease from conditions like essential tremor (where DaT scan is normal)
The dopamine transporter (DAT) is a presynaptic protein that re-uptakes dopamine from the synapse back into the neuron. Its loss reflects loss of dopaminergic neurons in the nigrostriatal pathway.

Management (partially visible)

The page leads into management, which for Parkinson's disease includes:
  • Levodopa/carbidopa - gold standard (replaces deficient dopamine)
  • Dopamine agonists (pramipexole, ropinirole)
  • MAO-B inhibitors (selegiline, rasagiline)
  • Physiotherapy - gait training, balance exercises to address festination
  • Deep brain stimulation (DBS) - for advanced disease

Key Takeaway

The image illustrates how nigrostriatal dopamine depletion in Parkinson's disease manifests clinically as festinant gait, and how SPECT/DaT imaging provides objective, functional evidence of this dopaminergic loss - particularly the characteristic reduction in the posterior putamen - confirming the diagnosis.
  • Kaplan & Sadock's Comprehensive Textbook of Psychiatry, Dementia with Lewy Bodies section - "One would expect to see reduced dopamine transporter uptake in the basal ganglia on a DaT scan"
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