Pantothenate Kinase-Associated Neurodegeneration (PKAN) Clinical Presentation

Updated: Dec 07, 2016
  • Author: Philip A Hanna, MD; Chief Editor: Selim R Benbadis, MD  more...
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Presentation

History

Symptoms in pantothenate kinase-associated neurodegeneration (PKAN) include the following:

  • Dystonia - A prominent and early feature
  • Significant speech disturbances - Can occur early
  • Dysphagia - A common symptom; caused by rigidity and corticobulbar involvement
  • Dementia - Present in most individuals with PKAN
  • Visual impairment - Caused by optic atrophy or retinal degeneration; not uncommon and can be the presenting symptom of the disease, although this is rare
  • Seizures - Have been described [18]

Clinical manifestations of PKAN vary from patient to patient. The symptoms usually begin in the first decade with a motor disorder of extrapyramidal type and gait difficulty. Extrapyramidal symptoms dominate the clinical picture and include rigidity, slowness of movement, dystonia, choreoathetosis, and tremor.

In patients with atypical PKAN, extrapyramidal dysfunction may be delayed for several years, and spasticity and dysarthria may be the presenting symptoms.

Next:

Physical Examination

Physical examination reveals signs consistent with extrapyramidal and corticospinal dysfunction. In addition to rigidity, dystonia, and chorea, patients may exhibit spasticity, brisk reflexes, and extensor plantar responses.

Based on the common clinical features, the following diagnostic criteria for PKAN have been proposed. [18] For a definitive diagnosis, all of the obligate findings and at least 2 of the corroborative findings should be present. None of the exclusionary factors should be present.

Obligate features of PKAN include the following:

  • Onset during the first 2 decades of life
  • Progression of signs and symptoms
  • Evidence of extrapyramidal dysfunction, including 1 or more of the following: dystonia, rigidity, choreoathetosis

Corroborative features include the following:

  • Corticospinal tract involvement
  • Progressive intellectual impairment
  • Retinitis pigmentosa and/or optic atrophy
  • Seizures
  • Positive family history consistent with autosomal recessive inheritance
  • Hypointense areas on magnetic resonance imaging (MRI) involving the basal ganglia
  • Abnormal cytosomes in circulating lymphocytes and/or sea-blue histiocytes in bone marrow

Exclusionary features include the following:

  • Abnormal ceruloplasmin levels and/or abnormalities in copper metabolism
  • Presence of overt neuronal ceroid lipofuscinosis, as demonstrated by severe visual impairment and/or seizures that are difficult to control
  • Predominant epileptic symptoms
  • Severe retinal degeneration or visual impairment preceding other symptoms
  • Presence of familial history of Huntington chorea and/or other autosomal, dominantly inherited neuromovement disorders
  • Presence of caudate atrophy on imaging studies
  • Deficiency of hexosaminidase A
  • Deficiency of ganglioside monosialic acid-1 (GM1)–galactosidase
  • Nonprogressive course
  • Absence of extrapyramidal signs

Patients with atypical PKAN show more varied clinical features, with slower progression. Presenting symptoms usually involve speech defects, such as palilalia (repetition of words or phrases), tachylalia/tachylogia (rapid speech), and dysarthria (poor articulation, slurring). Motor involvement is usually a later feature. Onset is in the first three decades (mean age 13.6 years). [37]

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