MR spectroscopy of a bright cerebellar lesion in a patient with Langerhans cell histiocytosis

Deficient pain modulatory systems in patients with mild traumatic brain and chronic post-traumatic headache: implications for its mechanism

Although the prevalence rate of chronic post-traumatic headache (CPTHA) after mild traumatic brain injury (TBI) reaches up to 95%, its mechanism is unknown, and little is known about the characteristics of the pain system in this condition. Our aim was to investigate the capabilities of two pain modulatory systems among individuals with CPTHA and study their association with CPTHA, here for the first time. Forty-six subjects participated; 16 with TBI and CPTHA, 12 with TBI without CPTHA, and 18 healthy controls. Testing included the measurement of heat-pain (HPT) and pressure-pain (PPT) thresholds in the forehead and forearm, pain adaptation to tonic noxious heat, and conditioned pain modulation (CPM).The participants completed a post-traumatic stress disorder (PTSD) questionnaire. The two TBI groups did not differ in the TBI and background characteristics. However, TBI patients with CPTHA had significantly higher HPT and lower PPT in the cranium and higher PTSD symptomatology than TBI patients without CPTHA and healthy controls. Adaptation to pain and CPM were diminished in the CPTHA group compared with the two control groups. The intensity of CPTHA correlated negatively with cranial PPT, magnitude of pain adaptation, and CPM. CPTHA intensity correlated positively with PTSD symptomatology. CPTHA appears to be characterized by cranial hyperalgesia and dysfunctional pain modulation capabilities, which are associated with CPTHA magnitude. It is concluded that damage to pain modulatory systems along with chronic cranial sensitization underlies the development of CPTHA. PTSD may reinforce CPTHA and vice versa. Clinical implications are discussed.

Early Diagnosis and Monitoring of Neurodegenerative Langerhans Cell Histiocytosis

Background

Neurodegenerative Langerhans Cell Histiocytosis (ND-LCH) is a rare, unpredictable consequence that may devastate the quality of life of patients cured from LCH. We prospectively applied a multidisciplinary diagnostic work-up to early identify and follow-up patients with ND-LCH, with the ultimate goal of better determining the appropriate time for starting therapy.

Methods

We studied 27 children and young adults with either ND-LCH verified by structural magnetic resonance imaging (MRI) (group 1) or specific risk factors for (diabetes insipidus, craniofacial bone lesions), but no evidence of, neurodegenerative MRI changes (group 2). All patients underwent clinical, neurophysiological and MRI studies.

Results

Seventeen patients had MRI alterations typical for ND-LCH. Nine showed neurological impairment but only three were symptomatic; 11 had abnormal somatosensory evoked potentials (SEPs), and five had abnormal brainstem auditory evoked potentials (BAEPs). MR spectroscopy (MRS) showed reduced cerebellar NAA/Cr ratio in nine patients. SEPs showed sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for predicting ND-LCH of 70.6% (95%CI, 44.0%-89.7%), 100% (69.2%-100%), 100% (73.5%-100%), and 66.7% (38.4%-88.2%), respectively. Repeated investigations in group 1 revealed increasingly abnormal EP parameters, or neurological examination, or both, in nine of fifteen patients while MRI remained unchanged in all but one patient.

Conclusion

A targeted MRI study should be performed in all patients with risk factors for ND-LCH for early identification of demyelination. The combined use of SEPs and careful neurological evaluation may represent a valuable, low-cost, well-tolerated and easily available methodology to monitor patients from pre-symptomatic to symptomatic stages. We suggest a multidisciplinary protocol including clinical, MRS, and neurophysiological investigations to identify a population target for future therapeutic trials.