Diagnostic algorithms

Diagnosis of NCL type can be challenging. This page contains several algorithms that should help. They aim to provide a sensible logical approach to the investigation of those who may have NCL. Algorithm A is for use in cases where the first presenting clinical feature is visual failure and the main differential diagnoses are juvenile onset NCL with typical or atypical ultrastructural feature, and a variant late infantile NCL. Algorithm B is for use in cases presenting with other neurological problems between the ages of 1 and 7 years. The most frequently encountered diagnoses will be infantile and variant late infantile NCLs in Finland and classic and variant late infantile NCLs in the rest of Europe. The diagnoses of Northern epilepsy, caused by a specfic mutation in CLN8, teenage and adult onset NCL and congenital NCL are not considered here. An alternative algorithm is also appropriate for cases presenting with other neurological problems between the ages of 1 and 7 years.

Clinical features and investigations are given in boxes.
Abbreviations used are:
CVB curvilinear bodies
EEG electroencephalogram
EM electron microscopy
FPP fingerprint profiles
GROD granular osmiophilic deposit
INCL infantile onset NCL
JNCL juvenile onset NCL
JNCL/GROD juvenile NCL with GROD
LINCL late infantile onset NCL
MRI brain magnetic resonance imaging
PPT palmitoyl protein thioesterase 1
RL rectilinear profiles
VEP visual evoked potentials

NCL algorithm A (pdf file)

NCL algorithm B (pdf file)

NCL algorithm alternative (pdf file)

A simpler protocol that can be followed once a diagnosis of NCL has been reached or strongly suspected is included to guide through the tests now available.

NCL diagnostic protocol (pdf file)