Choreiform Movements

Chorea or ballismus has been observed in the hyperosmolar hyperglycemic state (76). In a report of HHS patients presenting with chorea, the mean age was 71.1 years and had a 2:1 ratio of women to men (76). In patients with HHS, choreiform movements are often but not always unilateral and occur concurrent with or shortly after the episode of hyperglycemia (77). Diabetes is usually newly diagnosed in these patients and develops subacutely over days to months (77).

In states of hyperglycemia, potential pathological causes of choreiform movements include decreased GABA-enkephalin inhibitory neurons, intracellular acidosis, accumulation of extracellular glutamate, brain edema formation, disruption of the blood-brain barrier, and global decrease in cerebral blood flow (78, 79). Resolution of hyperglycemia and increases in GAB A levels do not always reverse chorea (77, 78). Chronic arteriolar disease and lacunar infarctions have been proposed as a mechanism, but subacute development of disease, generalized distribution of chorea in certain cases, and new-onset diabetes argue against these etiologies. Autoimmune attack, possibly via anti-GAD65 antibodies with opening of the blood-brain barrier has been proposed. Yet, anti-GAD65 antibodies were absent in the majority of patients in one study of HHS and chorea (77). MRI findings in patients with HHS and chorea may be abnormal and involve contralateral striatal hyper-intensities on T1-weighted MR imaging, uniformly present in the putamen and usually involving the caudate (77, 78). In a rat model of transient focal ischemia, T1 striatal hyperintensities were present and histology revealed no hemorrhage or infarct, but did show diffuse and selective neuronal death and proliferation of astrocytes (80). These findings were similar to biopsies of the striatum in a human suffering with chorea, but not HHS (81). The metabolic derangements present in hyperglycemia may render the striatum vulnerable to partial neuronal death and dysfunction and ultimately cause transient or permanent choreiform movement.

Blood glucose control, neuroleptics, and benzodiazepines are the mainstays of therapy for this neurological complication. Ventral thalamotomy has been used successfully in one case (76). Abnormal movements usually resolve or improve after hyperglycemia treatment in the majority of patients (76).

Seizure Activity

Seizures can present in up to 25% of patients with HHS (82). The majority are partial (83, 84), but generalized tonic clonic seizures can also occur or may present secondarily. Epilepsia partialis continua (EPC), a rare simple partial motor seizure restricted to one part of the body (85)is a common form of seizure activity in HHS, observed in 14 of 21 patients in one study (83). Movement-induced or kinesigenic and gaze-evoked visual seizures have also been reported (72, 86). Brick et al. described reflex epilepsy in five patients with HHS who repeatedly induced focal seizures by limb movement (87). Non-motor seizures may also occur and may be less recognized as symptoms include apnea, speech arrest, aphasia, somatosensory symptoms, visual disturbances, and cardiac arrhythmias (64).

Potential mechanisms for increasing risk in HHS may include hyper-glycemia, hyperosmolarity, low levels of GABA, and focal ischemia (83). GABA is an inhibitory transmitter that lowers the seizure threshold. GABA is decreased in HHS secondary to increased metabolism (85). Additionally, seizure activity is rarely witnessed in DKA where GABA levels are increased secondary to increased activity of glutamic acid decarboxylase and acidosis (71, 85). Others have postulated that pre-existing areas of focal ischemia in cortical lesions may foster epileptogenic foci in periods of altered metabolic conditions (85). Other studies suggest that hyperglycemia can result in reversible focal ischemia without structural damage by decreasing blood flow in specific cerebral areas (88).

Although MR imaging is typically unremarkable (85, 89-91), various studies have reported abnormal findings. In case reports, patients with partial status epilepticus and HHS showed transient subcortical T2 MRI hypointen-sities near the epileptic focus (75, 91) that correlated well with EEG as well as striatal T2 hyperintensities (91). Abnormalities are typically reversed on repeat imaging weeks to years later. Other studies have also reported transient focal lesions on computed tomography (82).

Seizure activity in HHS is treated by insulin and rehydration reducing hyperglycemia and hyperosmolarity. seizure activity stops immediately after the treatment of hyperglycemia by insulin (82, 83, 86) and can recur if glucose is not controlled (86). seizures are often refractory to anti-epileptic medications (64, 82, 86, 92).

Other Neurological Manifestations other neurological manifestations of the hyperglycemic hyperosmolar state have been reported. Hallucinations, which may precede stupor or coma are usually visual and may range from simple to complex images or scenarios (70). Other neurological abnormalities described include tonic eye deviation, nystagmus, abnormal papillary reflexes, aphasia, hemisensory defects, unilateral hyperreflexia, Babinski signs, abnormal body tone, hyperpnea, and meningeal signs (67, 70). Meningeal signs include nuchal rigidity, positive Kernig's sign, and photophobia. The cerebrospinal fluid demonstrates no evidence of infection, but high glucose levels increased osmolality, and hyperchloremia may be present (70). These changes suggest diffuse cortical or subcortical damage, which is usually reversible with correction of the underlying metabolic abnormalities (67).

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  • elijah
    What is diffused choreiform?
    7 years ago

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